ANNUAL REPORT OF THE

WATER DEVELOPMENT DEPARTMENT

FOR THE YEAR 1961

CONTENTS

Photographs I Introduction

II Policy

III Organization

IV Staff: I. General 2. Training Courses 3. Staff-Time Analysis

V Buildings VJ Equipment, Plant, Vehicles, and Watercraft

VII Hydrological Survey:

1. General Rainfall

3. Evaporation 4. River Flow 5. Suspended Sediment Measurement 6. Hydrological Survey Stations

VUI Hydrological Rcsearch: 1. General 2. Evaporation Studies 3. Catchment Research

IX Advisory Services on 'Vater Development: I. General 2. Hydro-electric Schemes 3. Land Reclamation and Irrigation Schemes 4. Water Supply Schemes 5. Flooding and Drainage 6. Dams

X Construction:

XI

I. General 2. Hydrological Survey Stations 3. Water Development Projects 4. Buildings

Drilling: I. 2. 3. 4. 5. 6. 7.

General Analysis of Boreholes Drilled in 1961 Southern Province Drilling Central Province Drilling .. Northern Province Drilling The I-Iand-rig Experiment The Boreholc Subsidy Scheme

XII Water Law Xln Conclusion ..

TABULATED DATA AND DIAGRAMS

Diagram illustrating the organization of the Department Staff List for 1961 Table of Boreholes drilled in 1961 EvapOl'ation at Selected Stations Shire River Flow Information River Flow Information--Sonthern, Central and Northern Provinces l'vlonthly Flows at Selected Stations Summary of Silt Factors Shire River I-Iydrograph at Livwude Ruo River Hydrograph at Sankulani Lilongwe River H,ydrograph at Lilongwe Bna River Hydrograph at Bua Bridge South Rukurn River Hydrograph at PW0zi

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Un centre) 5 5

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7 7 7 8 8

9 10 10 11 11 II

12 12 14

14 14 14 15 16 16

16 16 17 17

18 18 19 20 21 22 23

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25 26 27 30 31 32 34 35

:: Lt end

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I. Introduction

In 1961 the output of work by the Department was in some ways disappointing and in others encouraging: the year's prodnction of 108 boreholes was rather low and reflected the shortage of senior staff in the Drilling Section; the hydrological survey of Nyasaland continued at a steady rate; and in two of the newer parts of the work, training of junior staff and construction of water development projects, creditable progress was made.

Once again there was an expansion in the demand for advisory services on water development problems, and due to a shortage of professional engineers it was difii.cult to satisfy the demands promptly. Nevertheless a considerable amount of work of this kind was carried out.

This report describes in detail the work of the Department in the calendar year l!l61. It should be noted however that the hydrological data given in the appendices relate to the hydrological year which ended on 31st October, 1961.

n. Policy

The Department's aims are to conserve and increase those water resources of the territory that are of use to man, to develop the uses of water to the best purpose, and to arrange that harmful excesses of water do the least amount of damage. These aims have never been fully achieved, but it is towards their achievement that the various parts of the work of the Department are directed.

In gen.eral the body of this report contains descriptions of the measure of success attained in 1961 in implementing the Departmental policy. The report is divided into sections according to the type of work described, and before considering the report it is of interest to note the various ways in which the Department works to implement the policy. A list of the major functions of the Department is given below:

(a) Hydrological surveying.

(b) Hydrological research.

(c) Drilling boreholes for water supplies.

(d) Maintenan.ce of boreholes.

(e) Construction of irrigation schemes and rural water-supply schemes.

(f) Advisory services on groundwater sources.

(g) Advisory services on surface-water sources.

(h) Advisory services on hydraulic engineering.

Because there is no established school that gives extensive training in hydro­logical surveying, the Department has always had to undertake the training of staff for this work. The emphasis now placed by the Government on training courses reinforces the Departmental policy on this matter. An additional major function of the Department is now therefore:

(i) Training of technical staff.

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HI. Organization

The method of working of the Department that was followed until the middle of 1961 was laid down in early 1957. In 1961, however, it was found that conditions had changed so as to warrant reorganization of the work, and accordingly the scheme of working that is illustrated in the diagram at page 25 of this report was devised and brought into use.

The more important changes in the organization were the merging of the Southern Province work in the Headquarters work, the decentralization of the borehole mainten­ance work, and the division of the Headquarters staff into more definite sections, each with its own laid-down organization. The changes were designed to make the best use of professional and technical staff, the shortage of which persisted throughout the year, and to meet the increased demand for services requiring the direction of professional engineers.

Referring to the organization diagram it will be seen that the Department has three levels: Headquarters, run by the Chief Executive Engineer; the Lilongwe office, run by the Water Development Engineer at Lilongwe; and the Mzimba office, run by the Hydrological Assistant at Mzimba.

At Headquarters there are five sections, each dealing with a number of allied functions, and each headed by a suitable officer who is responsible to the Chief Executive Engineer for the work of his section. Some of the sectional functions are carried out under the direction of the Lilongwe office and some under the direction of the Mzimba office. For the Northern Province work the Hydrological Assistant at Mzimba is responsible to the Water Development Engineer at Lilongwe, while the Water Development Engineer at Lilongwe is responsible to the Chief Executive Engineer for work in both the Northern and Central Provinces. The section heads are advisors to the Provincial heads for the Provincial work relating to their sections, but executive responsibility between Headquarters and the Provinces flows through the Chief Executive Engineer.

The Director was on vacation leave from the beginning of the year until 31st January, and during this period the Chief Executive Engineer acted as Director. For lack of engineer staff of sufficient service no acting appointment of Chief Executive Engineer was made.

The post of Senior Geologist, which was brought out of abeyance on 1st July, remained unfilled for the rest of the year. During this period the Chief Executive Engineer was responsible for the work of the Drilling Section as well as for his more general responsibilities.

The Mechanical Supervisor was on vacation leave from the beginning of the year until 4th May. A Temporary Mechanical Supervisor was available as a relief for one month of this period, but for about three months the work of the Transport and Workshops Section was insufficiently guided, resulting in some delay in the Depart­ment's work due to lack of serviceable vehicles.

The accent on training, which was one of the features of the work in 1961, did not affect the Department's organization; the courses run by the Department were all in­service training courses, all but two of the trainees were supernumeraries being members of the Government's Joint Training Pool, and the day-to-day planning of their courses was done by the heads of the sections in which they worked.

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IV. Staff 1. GENERAL

The list at page 20 of this report shows the 1961 establishment and start posItion of the Department as far as the more senior posts arc concerned. At mid-year the post of Senior Geologist was taken out of abeyance, one post of GeologIst was removed, and one post of Senior Storekeeper was put into abeyance. Two Hydrological Assist­ant posts and the Works Supervisor post remained in abeyance the whole year, and the post of Drilling Superintendent was allowed to lapse on the retirement of the holder.

The post of Senior Geologist remained vacant from the time of its being taken out of abeyance, throwing a heavy burden of work on other members of the Drilling Section. The Water Development Section, however, was relieved to some extent by the appointment in the latter part of the year of a Temporary Works Supervisor, who was appointed tinder a Colonial Development and Welfare Scheme for Irrigation and Water Development.

During the year, further appointments were made from the Departmental sta'f to the Government's Joint Training Pool. The list of more senior staff shows three such appointments: two Hydrological Assistant Trainees, and one Senior Field Assistant who is being trained with a view to his becoming eligible for promotion to Hydrological Assistant Trainee.

No important changes were made in the Department's establishment ot JunIOr staff, but five Training Pool posts, in addition to those mentioned above, were added to the Department's staff. These posts are described in the next section of this report

2. TRAINING COURSES

Seven members of the staff underwent training courses during the year: a Scnior Storekeeper completed a short Ministry of Works and Transport course in store­keeping, a Clerk completed a short part-time training course for Goverrunent clerical officers at the Commercial Training Centre, Blantyre, and five members of the staff received Departmental in-service training.

In-service training courses were given in hydrological surveying work and in draughtsmanship. Four of the staff received training in hydrological surveying: two Hydrological Assistant Trainees, one Senior Field Assistant, and one Field Assistant; and one Tracer received training in draughtsmanship. The latter, after two months training, rcsigned to take up an engineering scholarship in Germany.

At the end of the year, three Mechanics from the Ministry of Works and Trans­port were appointed as Driller Trainees in the Department for an in-service course in percussion drilling of boreholes planned to start at the beginning of 1962. It was hoped to start this course with six Trainees, but out of many applicants only three suitable candidates could be found.

3. STAFF-TIME ANALYSIS

In general there was no difficulty in recruiting junior staff, but some senior staff posts were found difficult to fill. The productivity of the Department is largely controlled by the senior stafi position, and therefore an analysis of the productive time of the more senior staff as listed in this report is of interest. The total senior staff and Grade IH junior staff establishment, excluding posts in abeyance but includ­ing Training Pool posts and the Temporary Works Supervisor, averaged 36tposts for the year. Taking 36t man-years as 100 per cent. total establishment staff-time, and allowing for vacancies, leave, and relief-staff time, the productive staff-time for 1961 may be calculated thus:

7

... --.-._----------"------

Vacancies time , . Vacation lean: c;.l1d tr(tv(~.llijJg Local leave . Sick leave

Unproductive time Deduct for :rclief~st(JJf time

Net unproduct.ive time Flrocluctive time

'rotal establishment SL.i!f-till1C:

Per cent. 13.0 15.1 2.3 1.2

31.6 1.5

30.1 69.9

100.0 ===

The productive time figure is particularly low, and this is attributable to the high proportion of vacant posts caused by the lack of Water Development Engineers, of a Senior Geologist and a Geologist, and of a Driller. A more detailed analysis shows that the productive time for the Water Development Engineer establishment was only 44 per cent., and for the Drilling Section establishment only 63 per cent.

The productive time of the Hydrological Survey Section, calculated in the same way, was 71 per cent. The seven seniOT-staff members of this section had, however, five junior-staff trainces to instruct, and thus the time spent on hydrological survey work was considerably reduced by the demands of the traini:ng programme.

V. Buildings

In April a dwelling house situated between the Stores Depot and the Workshops was taken over by the Department as additional office accommodation for Head­quarters staff. Onc room was equipped as a laboratory, and the old laboratory which was inadequately housed in a prefabricated building in the Workshops area was dismantled.

Following the acquisition of this new office, the Ministry of Works and Transport constructed a connecting road between the main road, the workshops, the new ofii.ce, and the Stores, and as a result it becamc possible to close the old entrances to the Workshops and the Stores, the accesses to which were through land occupied by the Ministry of Works and Transport. The new arrangement allowing better control of traffic and affording greater security is more satisfactory to both parties than the old.

A fire-proof room, for the storing of hydrological survey records, was added on to the rear of the Computor's office early in the year.

A new house for the Gauging Assistant in charge of the Fort Johnston area gauges was completed in August.

VI. Equipment, Plant, Vehicles, and Watercraft

Four new vehicles were received to replace others declared unserviceable by Boards of Survey. Three of the vehicles were fitted with canopies, and one was also fitted with a collapsible lifting boo111 for use on borehole maintenance work. These modifications were carried out in the Department's workshops.

Three new boats were built Departmentally for use in hydrological surveying.

The equipment of the mechanical workshops was increased by the purchase of a surface plate and a spark-plug tester.

Six Gunn-Bellani radiation integrators were purchased for use in evaporation research work and were sent to the Goetz Observatory, Bulawayo, to be calibrated by the Federal Meteorological Department.

S

Except for a short period of the year when the Mechanical Supervisor was on leave and his post was without a relief, the Workshops stafl maintained the Depart­ment's plant, vehicles, and equipment, in a good state of serviceability. In addition to the normal maintenance and repair work, which included several complete over­hauls, much useful fabrication work was undertaken over and above that already described. This included the rebuilding of a caravan, the prefabrication of a gauging footbridge, the manufacture of numerous pieces of equipment and parts for gauging stations, and the production of the year's supply of about 200 bush-type, borehole hand-pumps.

VII. Hydrological Survey

1. GENERAL

In the early stages of the development of Nyasaland, the water resources were relatively less important; nor do they now play the prominent role that they seem destined to assume in the future. In the early days these resources were normally adequate to meet the limited needs that existed, and as a result little concern was felt regarding the need for knowledge of the ultimate capacities of our rivers and under­ground sources to meet the many demands to which they now are, and in the future will be, subjected. In 1948 the regular collection of hydrological data in Nyasaland was commenced on a very limited scale, although lake levcls had been recorded since the beginning of this century. In 1952 there was a considerable expansion of the survey to meet a demand for hydrological data on the Lake Nyasa-Shire drainage system, which data eventually formed the basis upon which the proposal for the Shire Valley Project was made in 1954. During this period ef£o1't was concentrated in the Lake Nyasa-Shire drainage-area of the Southern Province, and to a certain extent, in the extreme northern part of the Lake Nyasa basin, but on the completion of this investi­gation the hydrological survey was expanded to provide a more representative cover of the entire country to meet the growing demand for hydrological data in connection with water supply, irrigation, power, land reclamation, and flooding. As a result, a network of river, lake and swamp gauges, and evaporation stations, is now well established, and the data collected is becoming more valuable with each passing year, enabling more accurate assessments of long-term conditions to be made. The density of the hydrological net-work in Nyasaland is comparable with other more highly developed countries, but this has been dictated, firstly, by the large areas of lake and swamp in a broken and variable surface form, providing for a great variation of hydrologic conditions, and secondly, by the comparatively dense and rapidly increaf ing population on the land.

Therefore, whilst there was no expansion of the hydrological survey during the year, work continued on the improvement of the present network of gauging stations by constructing weirs, automatic-recording water-level gauges, artificial controls, and cableways. To improve the representation of the network in localized areas some new stations were opened and others, found unsatisfactory, closed down. As a result of this work there was a net decrease of ten regular metering stations and an increase of one gauging weir and one evaporation station. The decrease in the number of regular metering stations was brought about by the closure, or down-grading to occasional gauging sites, of a number of stations originally opened for specific investigations.

The following table sets out the growth of the hydrological survey network over the past ten years, and it will be noted that, whilst the number of river gauging and evaporation stations has remained static over the past five years, there has been a steady increase in the number of gauging weirs, automatic-recording water-level gauges, and artificial controls constructed at these stations. In reading the table it should be noted that the automatic-recording rain-gaugcs shown are only those installed for investigations for specific projects as, in general, rainfall data are obtained from the Federal Meteorological Department.

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1\);-; I I $).jli Jj)(;]

Hegular :\1ctering Station::> :?;"') I !D ! ! ;) H.eglllar Gauge Height Sta lions ;) ij j ·1 i Evapuration Stations Cii I :lll :3 :3 Cauging \Vcirs i\il 10 20 .\ II toma tic- H.cl:onling \Vatcr-],cve] Callg('~; Ciil " ., J ;)

:\ utomatic-Hecol"lling J~ain-(;auges i\il is g Artificiai Control Structures Nil >:il :!O Cab:e\\·,l\·S Xii 8 11

Current-meter measurements at both regular metering stations and miscellaneous sites continue as the major function of the Hydrological Assistant and Field Assistant staff, and during the year a total of 2,079 current meter measurements were made, of which 746 were made at miscellaneous sites in connection with specific water develop­ment schemes. The amount of investigational work being carried out by consultants for various projects slackened off during the year, and as a result the number of miscellaneous measurements was less than that made in 1960.

2. RAlNFALL

The 1960-61 rainy season was characterized by its general patchiness, although the average fall over the whole Protectorate was 3 per cent. above the long-term mean. In the Southern Province, rainfall amounts were below normal in a zone that extended from Chikwawa through Cholo to Mlanje, whereas on the boundary of this zone high totals were recorded. Blantyre and Chiromo recorded twelve inches and nine inches above their normal totals respectively, and in the case of the former the season was the wettest in ten years and the second wettest in 25 years. In the Central Province, totals were generally above normal except along the escarpment areas of Dedza and Dowa, and Fort Manning experienced its wettest year for 40 years. In the Northern Province the Lake-shore escarpment areas received more rain than the plateau areas of Mzimba and Fort Hill.

Rain associated with an influx of moist south-easterly air commenced in mid­November and became more widespread with the formation of the Inter-Tropical Convergence Zone during the first week of December. Towards the end of December there was a major advance of Congo air, a deepened equatorial low, and a large invasion of south-east air, which caused heavy widespread rain. This condition continued throughout January an.d February with a retreat of the Congo Air Boundary in early March. By mid-April the Convergence zone had retreated with a general clearing from the south-east, but at the latter en.d of April there was strong influx of moist channel air that caused mist and prolonged light rain over high ground and the Lake-shore escarpment areas. During this period Mzuzu recorded ten inches of rain in seven days.

During May and June there were minor influxes of south-east air, and in mid­June an upper cold wave caused an unseasonable outbreak of thunderstorm activity in some areas. The remainder of the dry season was characterized by alternating periods of dry weather with eight separate influxes of moist south-east air which caused" chiperone " conditions over southern Nyasaland of varying intensity, that of the 7th-10th August being unllsually heavy.

3. EVAPORATION

As the result of a generally wet season, and temperature, sunshine hours, dew points, and wind speeds, being norn1al to below normal during the dry season, evapo­ration amounts were generally below average during the year. The table on page 00

10

shows the evaporation as measured by a standard pan at selected stations, and a com­parison is made with long-term means. This table also shows the equivalent pan evaporation from the American Class A-type pan, the accepted international standard. These Class A-pan totals are deduced from the Kenya-lVIinistry-of-Works-type pan that is in use in this country by a regression equation determined by direct comparison between the results from the two types of pan. The determination of the regression is described in the Hydrological Research section of this report.

At the end of the year there were 33 evaporation pans in use throughout the Protectorate, ten being at stations where a full range of meteorological factors affecting evaporation are measured, from which calculations of potential evaporation can be made. To improve the network of stations the Lilongwe town evaporation pan was closed and moved to a new station at Kasungu, and the Salima township evapo­ration pan was moved to the FederallVIeteorological Department's full-time station at Salima airport.

4. RIVER FLOW

A schedule of river flow information for the hydrological year, 1st November, 1960, to 31st October, 1961, is shown on pages 32 ancl33, and it will be seen that flows were generally above average resulting from above-average rainfall during the 1959-60 season, thus breaking a three-year period of progressive depletion of base flow in the majority of rivers. In the Southern Province the rivers draining the Chikwawa area and the Cholo highlands, however, had below-average flows, this being a direct reflection of the below-average rainfall conditions in this area during the preceding season. In the Central Province, flows were generally average to above average, and similarly in the Northern Province VI~th the exception of the rivers draining the northern Nyika plateau.

Lake Nyasa reached a maximum level of 1,551.0 on 16th lVIay, 1961, which was 0.6 feet below the maximum reached in 1960 and 4.ii feet below the very high level reached in May, 1937. The mean daily flow of the Shire I~iver out of Lake Nyasa, for the period 1st November, 1960, to 31st October, 1961, was 9,300 cusecs.

Tabulated data and hydrographs in this report cover many of the stations included in previous reports so that comparisons can be made. In considering the mean values the short period of time over which figures to date have been determined should be taken into account.

5. SUSPENDED SEDIMENT MEASUREMENT

As has been the practice since 1952, suspended sediment samples were taken during the year at all regular gauging stations. During the wet season samples were taken whenever a discharge measurement was made, but during the dry season samples were taken less frequently.

The suspended sediment data so obtained wcre used in conjunction with the rele­vant flow hydrographs and the total annual suspended sediment load for each river was expressed firstly in tons per square mile and then as the" silt factor" which is the ratio of total annual suspended load in tons to the annual water flow in acre-feet (tons per acre-foot). The silt factors for the year 1960/61 are shown in the table on page 00 with the average factors determined from measurements made, in some cases, over the past ten years. It may be observed that the factors are in general average to above average for 1960/61, and this is attributable to the general heavier rainfall and increased river flows experienced.

6. HYDROLOGICAL SURVEY STATIONS

In past years all construction and maintenance work for the hydrological survey stations has been carried out directly by staff of the hydrological survey section, but in 1961 a works construction unit was formed to undertake the major construction

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work for the hydrological survey stations and construction work for small water development schemes in rural areas. In lU61 the unit operated in the Southern Province only.

Works that were carried out by the works unit for the hydrological survey were the modification of the house and well of the automatic-recording water-level gauge on the Shire River at Liwonde, the construction of automatic-recording water-level gauge installations on the Lujeri River at Mlanje and on the H.ivi-Rivi River, and the construction of a combined control and low-flow gauging weii' on the Nkasi Stream at Kalembo.

The hydrological survey staff carried out all maintenance work on the stations and also built these new works: controls on the Mwanza and Palombe Rivers, cable traverses on the Lingadzi and South Hukuru Rivers, an automatic-recording water­level gauge installation on the Lilongwe Rivcr just upstream of the gauging weir at Lilongwe Town, and a footbridge for use in gauging the Chelinda River at Rumpi. Modifications to the approaches to the weir on the Likabula Stream at Mlanje were also made.

Fuller details of the construction works are given in the Construction section of this report.

VIII. Hydrological Research

1. GENERAl,

Hydrological research is undertaken by the Department as part of the routine hydrological survey work. Research has been facilitated by co-operation from other Nyasaland bodies engaged upon similar work through the agency of the Nyasaland Hydrological Co-ordinating Committee, which was set up in 1959 and which met on two occasions during 1961 to discuss currcnt work and to formulate plans for future work. There were four major items of research work that were dealt with by the Committee. These, with the bodies responsible for the research, were:

Soil Moisture and Consumptive Use-Department of Agriculture. Run-off from Tea Gardens-Soil Conservation Branch of the Department of

Agriculture, and the Tea Research Organization of Ehodesia an.d Nyasaland. Evaporation Studies-Water Development Department.

Run-off from Afforested Catchments-Water Developmen.t Department, and Forestry Department.

The two research projects for which the Department is responsible are described in detail below.

2. EVAPORATION STUDIES

This work has now evolved into three distinct but interrelated investigations: the determination of potential evaporation rates for the whole Protectorate, the study of the methods of measuring potential evaporation, and the study of the technique of reducing evaporation from open water surfaces by use of a monomolecular film.

In these stUdies the potential evaporation is estimated by Penman's approximate energy-balance method using the modification for calculation of the net radiation devised by Glover and McCulloch of the East African Agriculture and Forestry Research Organization. The instruments used in these studies are the usualmeteoro­logical instruments required to measure the data for insertion in the Penman equation, two types of evaporation pan (Kenya Ministry of Works pans and American Weather Buteau Class A pans), and Gunn-Eellani radiation integrators.

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· A nUJ11ber of stations are equipped with pans and with sufficient meteorological mstruments so that the Penman value of potential evaporation can be directly calculated. A larger munber of stations lmve only a Kenya-type pan, which is the standard pan for the Protectorate and for Kenya. A small number of stations have Class A-type pans which are now accepted as the international standard by the World Meteorological Organization.

The results of the 1961 studies are set out in the following paragraphs.

(a) Direct methods of measuring potential evaporation

Comparative studies of the relationship between results from the Kenya pan and the Class A pan were completed. Results from three stations, at Chiromo, at Blantyre, and at Lilongwe, which have widely differing climatic conditions, were compared. Though there was a slight difference between the regressions of ten-day means for these stations, the data were combined to give a general single regression of the Class A pan on the Kenya pan which was, in inches of evaporation for ten-day means, A=0.9750K-0.0045, with D6 per cent. of the variance accounted for, the unaccounted part being attributed mainly to the slight differences between the three stations. This regression will be of value in comparing Nyasaland evaporation rates with those obtained with Class A pans in other parts of the world. It has been used to convert the Nyasaland evaporation data to Class A pan results in the table at page 00 of this report.

Both types of evaporation pan used have been found troublesome to maintain and, in tropical conditions, are subject to numerous causes of error. The main cause of evaporation is solar radiation, and Gunn-Bellani radiation integrators, which measure radiation received, have been used in Kenya to measure evaporation with some success. These are convenient instruments, giving little trouble, and having the merit that they can be calibrated to make a direct measurement of evaporation. Accord­ingly a number of these instruments were installed at various evaporation stations throughout the country and an effort was made to correlate the integrator and pan results.

The high degree of correlation between ten-day means of pan evaporation and water distilled by the radiation integrator that was ob:ained in Kenya was not realized in Nyasaland. This is attributed to the fact that all Nyasaland pans are raised above the ground and are more susceptible to side-effects than those of the Kenya tests which were sunk below ground level, and to the effects of the greater values of the wind function that are obtained from Nyasaland conditions.

For monthly means, however, better correlations were obtained, but for many stations the correlation was too poor to justify the substitution of integrators for pans.

(b) Potential evaporation rates for Nyasaland

The methods used for estimating the potential evaporation were by Penman's method, where sumcient meteorological data were available, and by correlations between pan results and Penman estimates, and Gunn-Bellani measurements and Penman estimates, for stations where there was insufficient meteorological data. This study was aimed at producing et fust assessment of potential evaporation rates for the whole country, and by the end of the year the study was nearing completion.

(c) Reduction of evaporation

The spreading of cetyl-alcohol on the surface of a water supply reservoir near Blantyre, which was started in 1960, was discontinued at the close of the dry season of that year. From then and throughout 1961, data collection on inflow, outflow, and evaporation, continued, and these data will be used for comparison with data collected in ID60 and in future years, when cetyl-alcohol will again be used to reduce evapora­tion,

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il. CATCHMENT RESEAHCH

Long-term projects to study the rainfall/run-oft relationship of two catchments recently aftorested and to be afforested on Zomba Plateau and Chambc Plateau were continued. A further automatic recording rain-gauge was installed in the upper lVIlungusi catchment, bringing the total number of rain-gauges in the Zomba Plateau catclunent to eleven, two of which are of the automatic-recording type. Data on the physical characteristics and land use of both catchments were collated in the form of maps and reports, and copies of these data were submitted to the Sub-Committee for Run-oft and Erosion of the Southern '\ frican l~egional Committee for the Conservation and Utilization of the SoiL

Dr. H. C. Pereira, Director of the Agricultural Eesearch Council of WlOdesia and Nyasaland, paid two visits to Nyasaland during the year, and in the course of these he visited both research catchments.

IX. Advisory Services on Water Development

1. GENEllAL

The hydrological records kept by the Department are, in general, freely available to the public. Furthermore the Department is able to advise other Government Departments and the public on hydrological and hydraulic engineering matters. Advice is generally given in the form of a report, and reports for Government agencies are usually in considerable detail and contain specific proposals for development, while those for non-Government agencies are leeS detailed but aim to afford suffIcient information for the best line of development to be selected and for consulting engineers or manufacturers of special equipment, if appointed, to see clearly what is involved in the proposed development. During 1961, advice or data were supplied for a variety of schemes concerning hydro-electric, irrigation, water supply, drainage, and dam­construction schemes.

The geologists on the Department's staff are mainly engaged on siting boreholes for drilling by the Depm"tment. Their services are available, however, for locating groundwater for the needs of other Government Departments and for the public. The work of this nature that was done in 1961 is described in the Drilling section of this report.

2. HYDRO-ELECTRIC SCHEMES

In connection with the proposal to build a hydro-electric scheme on the Shire I~iver at Nkula Falls, hydrological data were supplied to the Federal Ministry of Power and their consulting engineers, Messrs. 1". E. Kanthack and Partners, and to the Tanganyika Government.

A proposal by the Dcpm tmcnt of Veterinary SCTvices for a hydro-electric scheme on the Luchenza River at Mikolongwc was investigated and reported upon.

3. LAND RECLAMATION AND IRRIGATION SCHEMES

Hydrological data on the Shire Valley continued to be supplied to the consulting engineers who formulated the Shire Valley Project, Messrs. Sir William Halerow and Partners.

Land-surveying and hydrological measurements were carried out for the investi­gation in respect of the report to be prepared on the rice-growing potential of the Lifidzi l~iver area of the shores of Lake Nyasa.

The Department advised the Government on the hydrological and engineering aspects of the report on the reclamation and irrigation of the Elephant Marsh that was prepared by Messrs. NEDECO, consulting engineers.

14

Eeports were prepared for the Department of Agriculture on proposals for irrigation schemes at its Bvumbwe Agricultural Experimcnt Station and at its pro­posed Lower Hiver Farm Institute at Makanga. Acccptable schemes were devised and construction was initiated.

At the Bvumbwe Station, water was needed for irrigation and for coffee pro­cessing. A design which included an earth dam, two pumping stations, two service reservoirs, and appropriate pipelines, and which was to be built in two stages was prepared, and by the end of the year the first stage had been built. Fuller details of stage I arc given in the Construction section of this report.

At the Lower l'<.iver Farm Institute, water was needed for irrigation only. The design for the scheme called for an intake on the river, a pumping station and rising main, and a balancing reservoir of earth wall construction. By the end of the year the piping had been ordered and tenders for the pumping plant invited.

A report was prepared for the Department of Veterinary Services on proposals for a combined irrigation and domestic wat.er supply scheme for Malema Livestock Centre near KalOnga. The recommendations of the report were accepted, and a design produced and materials for the job ordered for the Veterinary Department to install.

Advice was given to the Forestry Department on providing a water supply for nurseries at the Chongoni Silvicultural l'<.esearch Station near Dedza.

4. WATER SUPPLY SCHEillES

In general, domestic water supply schemes for Governmcn t stations are the concern of the lVIinistry of Works and Transport, but the Water Development Depart­ment deals with those schemes which are not primarily for the supply of domestic water, such as the scheme for Malema Livestock Centre mentioned above, and also is able to advise the public on domestic water supply problems.

Hydrological data were supplied to the lVIinistry of Works and Transport in connection with water supply schemes for Fort Manning, Domasi, and Ncheu, and to Messrs. Brian Colquhoun, Hugh 0'])onnc1l and Partners who are·consulting engineers to that Ministry for water supply work at Zomba, Cholo, and Karonga. Hydrological data were also supplied to the lVIudi l'<.iver Watcr Board, and to Messrs. lVIaggs and Keeble, consulting engineers to the Lilongwc Water Board.

In conjunction with the Ministry of Works and Transport the Department prepared a report for the Ministry of Natural Eesources and Local Government on the water supply problem at the proposed M'mbelwa Farm Institute in the Northern Province. The report contained specific proposals for a water supply scheme.

A report was prepared fOT the Department of Agriculture on the possible sources of water for the proposed water supply scheme at its Mbawa Station.

Hydrological survey work was undertaken for the Geological Survey Department in connection with a possible future need for water for development of mineral deposits at Kangankunde I-Iill.

For District Councils, reports were prepared on water supply problems at Nsiya Village, Zomba District, at l'alombc Market, lVIlanjc District, and at Section I of the Lunzu-Lirangwe Land Usage Scheme, Blantyrc District. At the last-named a small, water supply scheme was built, fuller details of which are given in the Construction section of this report.

Eeports on domestic water supply schemes were prepared for three missions, olle in the Northern Province and two in the Southern Province, and one mission in the Central Province was given advice on a water supply problem. A report on a water supply for a tea factory was made for an estate in the Northern Province.

15

5, FLOOlJJNG AND DRAINAGE

The Department openlcs a. Hood warning service for the Chiromo area where, at the confluence of the Shire ancll\uo .Rivers, floods are quite likely to occur in the wet season, In 19tH two warnings of flooding were put out, on the 10th and 30th March; in neither case did J100ding occur, but at the time of the first warning the Shire rose sufficiently high at Chikwawa to put the vehicle ferry out of action.

Estimates of Hood Hows at bridge,; and culverts were made for the Ministry of 'Norks and Transport for twclve 'lites and for consulting road engineers at four sites. More detailed How data were givcn to the Ministry of Works and Transport for one bridge site and onc ferry site, ,me! to consulting road engineers for two bridge sites. The Department collaborated with the Ministry of Works and Transport in designing a structure for an automatic-recording water-level gauge to be installed at Chirua Bridge to assist in accurate measurement of How data required by that Ministry.

G. DAMS

Where weirs, or dams to impound over 15 feet depth of water, are built under subsidy from the Loans and Subsidies Scheme for Nyasalancl Farmers, the Department is responsible for the design and supervision of construction of the works. There was, however, little work of this kind in 1961: there was supervision of construction for one earth dam in the Central Province, which still remained under construction at the end of the year, and in the Southern Province one masonry weir was designed, which was built by the estate-owner, and onc earth dam was designed.

Again, in general, when a Government Department builds a dam to impound over 15 feet of water, the Water Development Department is required to examine the project for safety. In 1961, onc such case was referred to the Department by the Department of Agriculture, and in this case the dam was re-designed.

In the particular case 01 dams built by the Department of Agricnlture under the Colonial Development and \Velfare Fund Scheme for dam-building, the restriction as to depth of water is relaxed ane! the depth criterion is 20 feet. During the year, three cases of dams designed to hold 20 to 25 feet of water were referred to the Department, examined, and approved for construction.

X. Constrnction

1. GENEHAL

Whereas in the past, construction work has been confmed to that required for the hydrological survey stations and has haclto be carried out by the hydrological sllrvey­ing staff as best they could, in the latter part of 1961 a small works construction unit was formed to do the larger works of this kind and to undertake the construction of small water development schemcs in rural areas. The unit operated ill the Southern Province only, an.d works in the other two Provinces, and minor hydrological works in the Southern Province, continued to be the responsibility of the hydrological surveying staff.

The construction works carried out during the year can be considered under three heads: Hydrological Survey Stations, Water Development Projects, and Build­ings. In the following paragraphs the works are described under those heads.

2. HYDHOLOGICAL SUHVEY STATIONS

(a) Measuring Weil'S

A 57-foot-long masonry weir was built across the Nkasi l'{iver. The weir was fittecl with a V-l1otch for measuring low flows, but for high Hows it will act merely as a control .

16

Contract-built dam at Bvumbwe Agricultural Station

Pumping installation at Bvumbwe for irrigation and processing of coffee

Conventional, engine-driven drilling rig

Departmelltally-bnilt,hand-powered drilling rig

(b) Controls

A 25-foot-Iong concrete wall was built across the Palombe River to improve the control section, and two ten-foot-Iong concrete walls were built across the Mwanza River to improve the control section.

(c) Atdomatic-recording water-level gauge installations

The existing installation at Liwonde on the Shire River was modified to take a new Ott recorder, and new installations were built on the Lilongwe l'l.iver just upstream of the existing measuring weir at Lilol1.gwe Town, on the Rivi I~ivi River at the control section, and on the Lujeri River just upstream of the Lujeri Tea Estate weir which forms the intake to the Estate hydro-electric power plant.

(d) Cable-traverse installations

Cable-traverse installations were constructed at gauging stations on the Lingadzi River and the South Rukuru River. The cable spans were 180 and 206 feet re­spectively, and at each installation the winding gear end of the cable was housed in a prefabricated shed.

(e) Gauging footbridge

A 30-foot-span footbridge was prefabricated in Blantyre, sent to Rumpi, and assembled there across the Chelinda River. The bridge is used to facilitate current­meter measurements on this turbulent, rocky-bedded river.

3. WATER DEVELOPMENT PROJECTS

(a) Bvumbwe Agricultural Experiment Station's Non-domestic-water Supply Scheme, Stage 1

There is at Bvumbwe Agricultural Experiment Station a domestic-water supply scheme which supplies borehole water and which is the concern of the Ministry of Works and Transport. Borehole supplies were limited and for the development of the station large quantities of water were needed for irrigation and for coffee processing. The Department produced a design for a non-domestic-water supply scheme and during the year constructed the first stage of the scheme.

Stage I comprised an earth dam containing 15,000 cubic yards of earth and forming a 25-million gallon impounding reservoir, a pumping station, 800 feet of 4" asbestos-cement rising main, and a 13,000-gallon reinforced-brickwork servicE' reservoir. The clam was built by contract administered by the Department, and the rest of the works by directly-employed labour.

(b) Chileka Dam Water Supply Scheme

Below Chileka Dam, which was built by the Department of Agriculture as a water conservation measure as part of the Lunzu-Lirangwe Land Usage Scheme, the Department constructed a small water scheme comprising two cattle-watering troughs and two stand-pipes.

4. BUILDINGS

A two-room house was built at Fort Johnston for the Senior Gauging Assistant in charge 01 the hydrological stations in the Fort Johnston area, five temporary houses were built at Upper Bemvu, near Ncheu, to house the crew of the wells mainten­ance unit whose base was moved during the year from Balaka to N cheu, and two kitchens were added to the Departmental housi.ng at Chilomoni, near Blantyre.

17

XI. Drilling

1. GENERAL

The main fnnction of the Drilling section of the Department is the provision of water snpplies for African villages by the construction of boreholes. The boreholes are fitted with handpumps, and the resnlting installations afford convenient and reliable supplies of good quality water.

This work can be divided into three main parts: siting the boreholes, drilling the boreholes and fixing the pumps. and maintaining the boreholes and pumps, For the siting, which is done by geophysical survey methods, geologists are seconded to the Department from the Geological Survey Department.

As a subsidiary function the Department drills boreholes for other Government Departments and, in some few cases where drilling contractors are not available, for private concerns. Also, subject to the prior requirements of Government work, the geo­logists' services are available for groundwater investigations on privately-owned land.

For the first two months of the year two geologists were available for siting bore­holes, but for the remainder of the year only one was available. The geologists carried out 163 surveys resulting in the selection of 131 borehole sites. Of these surveys, 106 were for village water supplies, 45 were for other Government Depart­ments, and 12 were for private concerns.

Drilling was carried out by six engine-driven percussion drilling-rigs and one hand-powered percnssion drilling-rig of which the latter was working on an experimen­tal basis only. Due to the lack of a Driller, for most of the year only five cngined-rigs were operated, two in the Southern Province, two in the Central Province, and onc in the Northern Province. The hand-rig operated mostly in the Northern Province.

The rigs completed 108 boreholes durin.g the year, 101 by the engined-rigs ~md 7 by the hand-rig. Full details of the boreholes are given in the tables at pages 00, 00 and 00 of this report.

The maintenance of the village water supply installations was carried out by five maintenance units based on Chiromo, Blantyre, Ncheu, Lilongwe, and Mzimba. Towards the end of the year the Chiromo unit was moved to Chikwawa and steps were taken to form a new unit to operate from Kasupe to relieve the Blantyre and Ncheu units of part of their work. At the end of the year there were over 1,100 bore­holes maintained by the five units.

During the dry part of the year a light drilling-rig was put into the field to clean out a number of boreholes in the Central Province that had diminished in depth due to silting. Seven were de-silted, and of these four were drilled slightly deeper, the total deepening amounting to 24 feet.

2. ANALYSIS OF BOREHOLES DRILLED IN 1961 Total boreholes drilled .. Total footage drilled Number of productive boreholes . Number of unproductive borcholes Proportion of success .. J?ootage of productive boreholes . Footage of unproductive boreholes Total tested yield . . . . Average depth of productive boreholes Average tested yield of productive boreholes NOTE: For purposes of calculation the yields of boreholes drilled by the hn.,nd-rig,

which were not fully tested for yield, were taken as 200g.p.h. each Nmubcr of boreholes drilled for village water supplies Number of boreholes drilled for other Government Departments Number of nrivate bo1'0ho1es drilled Number of hush band-pumps fitted Number of Climax hand-pumps fd tcd

18

108 13,163 ft.

96 12 89%

11,705 ft. 1.458 ft.

62,GOO g.p.ll. 122 ft. 650 g.p.h.

88 17

3 76

7

The output of boreholes in 1961 was rather lower than usual. This is attributable to one rig being out of commission for most of the year due to lack of a driller, and to the comparative shortness of the dry season when work usually proceeds at a swifter rate. .

The proportion of success at 89 per cent. was also lower than usual, the average rate in the four years that the Department has been drilling boreholes previously being 94 per cent. An analysis of the twelve failures is given below.

Failures due to drilling diffi.c111ti~):,) hut suCCC~~flll blHd10ies suh:;cquently drilled nc,)xby 2

l."ailun:s due to dry borehc,J<.:~~.>, i)ut sacccssful i)(Jrchoies:';~lbscqucntIy drilled nearby 4 F<-tiLtrcs due to dry borehoic;), lll) alternative ~jte selected as yet 4 Failure due to dry boreholcs, '-",iLl! altcrnatil:c silc subsequently drilled ah::o dry 2

It may be seen that two failures were due to drilling difficulties, which were in both cases loose boulders, and ten were due to misinterpretation of the geophysical survey results. The number of drilling failures was normal and acceptable, but the number of siting failures was above average.

The analysis above also shows that in the case of six of the failures it was sub­sequently possible to obtain water hom another borehole at a nearby site, and that in four other cases it may be possible to find water in the future. At only one site. Ludzi School in lYIzimba District, does it appear that it would not be worthwhile to drill again for groundwatcr.

The distribution of the b oreholcs by Provinces and Districts is shown in the table below, while gencml notes on the drilling work in each District are given in latcr paragmphs of this section of the report.

'-------_." . .,----------

S"outherfl. P},OZ!1:nce Port l-lendd Chojo ;\II'anje B!antvrc Z();l'lb~l. J<a:~llpc Fort J ohnston

SOlJT1-rEHN PROVINCE '1'OT/'.L

CenII'(l.( PY(7)h.'C/3

Jjlo!Ef'.ve 1 )0\\';;-'

K'-l';U n;~\l

CI::XTR."-L PlZOVI:-;CE TOT .. \L

;\lzimba Karonga :'~umpi

:\ORTJ-IEF'.N PROV1:-:CE TlYfAL

PHOT.:~CTOHATE TOTAL

3. SOUTHERN PROVINCE

4

3

o 5

j :2

2;') S 1

2D

" " 2

G

2

J 2

Most of the drilling in the Southern Province was in the Mlanje, ZO:l1ba, Kasupe and Fort Johnston Districts, but some boreholes were drilled in the Port Herald, Cholo and Blantyrc Districts.

19

(a) Port Herald District The four boreholes completed in this District all gave satisfactory yields including

the one drilled by the hand-rig at ll1akanga. All four sites selected were in the thick alluvium of the lower Shire River valley.

(b) ikfla12je District In this District difficulties were encountered both in siting and in drilling the

borehoies. As has been observed before, the geophysical survey results obtained often proved to be anomalous, and consequently sites that showed most promising electrical resistivity curves were liable to yield disappointing quantities of water. At the two sites selected in N.A. Mkhumba's area, when the boreholes were drilled, one borehole was dry and one yielded only 150 g.p.h. However, a su.ccessful replace­ment borehole, yielding 1,200 g.p.h., was drilled near the site of the dry borehole.

The drilling difikulties which were met were mostly due to boulders, and at two sites the boreholes had to be abandoned and drilling rc-started nearby. At Tuchila Farm Institute, however, the difficulties were due to running sands. The driller finally managed to case off the sands and succeeded in constructing a borehole having a test yield of 1,000 g.p.h.

(c) Z omba District Difficuities were also encountered in this District. At Mandawala Village where

the old borehole finally dried up after several years of poor service, a new borehole was drilled which ran into dry, very hard rock. This was abandoned, the rig was moved a short distance away, and a second hole was drilled which, when tested, succeeded in yielding 400 g.p.h. In this part of N.A. Chikowi's area, surface indications of geology tend to be misleading as the rock bars which frequently underlie the flat plain are not reflected in the topography.

At the site of the Songani Asian School borehole a similar difficulty in drilling occuned. Again the re-sited borehole was successful, yielding 690 g.p.h. 011 testing. Here it would appear that the original site just missed the narrow band of low resis­tivity which traverses the Songani Trading Centre.

(d) Kasupe District All the boreholes drilled in this District were successful, one ten-inch diameter

hole drilled for the Balaka Township Water Supply Scheme being particularly good in that it had a test yield of 3,200 g.p.h. which is well above the average for Nyasaland boreholes.

The borehole at Matola penetrated limestone from a depth of 70 feet to 130 feet, a thickness of 60 feet.

(e) Fort J ohnston District Of the six boreholes drilled in this District, five gave above-average yields and

one was dry. All four boreholes in N.A. Jalasi's area gave trouble in drilling due to running sands, the Tapwata Village borehole being particularly troublesome.

4. CENTIlAL PROVINCE

Work in the Central Province was mainly in the Lilongwe and Kasungu Districts but a few boreholes were also drilled in Dowa District.

(a) Lilongwe District Thirteen boreholes were drilled in this District, of which twelve were for rural

water supplies and one was for the Likuni Farm Institute. In general the boreholes yielded between 480 and 720 g.p.h. from the junction of fresh, biotite-rich gneiss and the weathered upper layers. Water was consistently met at a depth of 130 to 70 feet over the whole of the District.

20

Two outstanding successes were at S.l" .A. TS<lbango's Court, where a yield of 480 g,p.h, was obtained despite the very dil1lcult h~rrain! and at N .1\. lVIazengera's Court where a vcry rare, but distinct! ncgativc-positi\Tc-ncgativc electrical resistivity curve was obtained in the geophysical SUl'\'Cy 'lllc! the borehole yielded 1,200 g.p.h.

(b) Dowa Disirict

Drilling in the Dowa District was divided almost equally between the Salima Lake-shore area and the Dowa hill-area.

In the Salima Sub-district the two holes clrilled for viilage water supplies gave disappointing results, onc being dry and the other yieldinG only 320 g.p.h. A borehole drilled for the Salima Police Lines, however, yielded 1,500 g.p.h.

The four hill area borch01es were all for village water supplies. Three gave fully acJequate supplies but onc at lVIkotamo Village yielded only 120 g.p.h. It was put into use, however, as thci-c was a shortage of other water supplies for the village.

The geophysical survey made in order to site boreholes for the Salima Township 'Vater Supply Scheme presented some interesting results which seemecJ to indicate that there were at least two main water-bearing horizons beneath the township area. A careful examination was made of the results obtained from boreho18s previously drilled which seemed to confirm this indication. As a high yield is required for the town­ship scheme, it was arranged that the new boreho18s will be drilled through the upper horizon, at about 70 feet depth, to reach the lower horizon at about 140 feet depth.

(c) Kasungu. District

The Kasungu District is notorious for its lack of both surface and subterranean waters and for the great dimculty that has been experienced in finding sucessful bore­hole sites. Only in the south-west of the District, in the region of the confluence of the Rusa ancJ the 13ua, is any appreciable thickness of alluvium found, and the three boreholes that were drilled in this part of the District during the year, at Kapala, Chaima, and Din/ala Villages, all proved successful, yielding 900 g.p.h. each on testing.

Elsewhere in the District selecting sites was found very difficult, but the results obtained from the boreholes were gratifying as from eight sites selected only one was a failure, that at Chaloamatambe Village. An alternative bo1'ehole site for this village was selected about half a mile away, but when drilled this yielded only 120 g.p.h. However, despite the poor yield a pump was fixed, as here again there was a shortage of other water supplies for the village.

5. NORTHERN P!{OVINCE

The cngine-driven rigs drilled 23 boreholes in thc Northern Province of which 17 were in lVIzimba District, nine in Karonga District, and onc in H.umpi District. The hand-powered rig drilled six boreholes in the Mzimba District. This section of the report does not deal with the hand-rig boreholes which are reported upon in the next section.

(a) 111 zim.ba Distrz:ct

In the first part of the year the drilling operations were confined to the south­western corner of the District where there is a great depth of weathering and where, as a result, seven successful boreholes were drilled. At lVIbawa Agricultural Station, however, in the same area, where a high yielding boreh01e was required, an eight-inch diameter borehole yielded only 130 g.p.h.

21.

Later in the y,'ar borchuJcs wcrc (lrilled in the northern part of the District. Here conditions were more dii1lcult clue to ullweathercc! a11(1 ullfractured quartzites being frequently CllCou;ltered. Of nine \)ordlOics drilled, three were dry, and four had yields which though usable WeTC wdl below the iwerage. Again an eight-inch dia­meter hole drilled at Hom for the proposed Northern Province Farm Institute yielded only :);50 g.p.h., though a high y.ield had been hoped for. Fortunately the boreholc was not wasted as it was brought into use for a village water supply.

Two of the three dry borchoj",; We,re at Lucll,i School. and onc was at Kasuni Village. The high incideilcc of fai,ur,,,; in this ;,rea reflects the diiflculty experienced in finding suitable sites in the arc".

(b) J(al'onga Dis/rict

Nine boreholes were (lrillc:cl ill this District, four Oil the Lake-shore and flve in the hills.

Of the Lake-shore hoJ.cs, three which WCTe for village water supplies were drilled in the thick sedimentary cover pre\'ilient in that region and gave adequate to good yields, and one drilled for the water supply for the new secondary school at Karonga yielded 880 g.p.h. obtained from an aquifer formed at the junction of fresh and weathered quartzite,

One of the hill-area boreholes proved dry, and another drilled at Fort Hill for the Witwatersranc1 Native Labour i\s:;()ciation yielded only 260 g.p.h. At this latter site the great thickness of dry sand at the surface precluded the undertaking of a complete electrical resistivity survey.

G. THE HAND-lUG EXPEEEdENT

As part of an attempt to find inexpensive ways of providing village water supplies, trials were made in the use of a light, hand .. powcred drilling-rig. The rig, which may be transported together with all its ancillary equipment and the materials for the bore­hole on a 25-hundredweight lorry, needs two men to power it, but as the work is arduous a gang of about six labourers is neeeled if the rig is to work a full day.

The hand-rig drills four-inch diameter holes, but its use is limited to those areas where the rock is soft and where water can be founel at fairIy shallow depths. In general, 70 feet is the maximum depth of bor8hole that can be drilled, and in such a hole the water must be no deeper than about 40 feet from the surface if the boreh01e is to be successfully developed for water supply purposes.

The way in which it was originally thought that the rig should be used was that it should be put into the field with two Departmental semi-skilled gangers, that trans­port from village to village should be by District Council lorries. and that labour should be obtained from volunteers in each village. Borehole casing, pumps, and other materials, would be delivered by Departmental transport, and the siting of the bore­holes and general supervision of the rig would become part of the routine work of the Department. The trials, which were designed to test this method and to reveal difficulties of working, started in late lUGO and fmished at the end of 1961.

During the trials, eight borehoIcs were drilled, one in 1960 and seven in 1961. At first there was little enthusiao3111 shown by villagers for volunteering their labour, but the position improved considerably towards the end of the tTials. The main difficulties in using the rig were found to be due to the unreliability of volunteer labour, the work being diff1cuit to plan and to supervise due to the erratic progress. No assistance in transporting the rig was volunteered by District Councils and it was found more convenient for planning to move the rig by Departmental transport.

22

It was concluded from the trials that the proposed way of working should be modified for convenience and economy by using more Departmental transport and by reducing the crew of the rig to one ganger. From the trials it appeared that, assuming the rig is only put to work in places where volunteer labour is assured, and that an average hand-driLled borehole would be about G5 feet deep, the rig could produce bore­holes at the rate of about one each month at the cost of about £75, including labour, materials and geophysical survey costs, but excluding transport and supervision costs, and general overheads.

Hand-rig 1;orehole5 have disadvantages as compared with the usual boreholes drilled by engine-driven rigs, but have the advantage in cost as the usual borehole costs about £400 calculated on the same basis as the £75 for the hand-rig hole. The main disadvantages of the hand-rig borchole are that being shallow they can only draw on a comparatively small groundwater reservoir and arc therefore likely to be less reliable and unlikely to give very high yields, and that though giving a less reliable supply they cost just as much to maintain as the usual borehole.

Considering all aspects of the use of the rig it was decided that the use of several rigs on an organized basis was worthwhile, and plans were made for putting further rigs into operation.

'7. BOREHOLE SUBSIDY SCHEME

The Department sites and supervises the constmction of boreholes drilled for farmers under the Loans and Subsidies Scheme for Nyasaland Farmers. During the year, six applications for subsidized borehoks were received, and for these applications three boreholc sites \vere fixed, one of which was drilled and approved for payment of the subsidy. On one farm 110 suitable site could be found, and at the end of the year there were two farms on which the borehole sites had not yet been fixed.

Seven borehole sites, relating to six applications made in 1960, remained un­drilled at the end of 1961.

XII. Water Law

The Department advises the Government on the granting and renewal of water licences, and during the year it dealt with 35 cases, of which 28 related to abstraction of water from streams and seven to impounding water by dams. In 1961 nine new water licences granted, five were renewed, and two were reassigned, and at the end of the year there was a total of 6G water licences extant, a number having expired or having been surrendered. Twelve water licence applications and one case of a renewal, all of which had been reported upon by the Department, were still under consideration by the Government at the end of the year, and there were five applica­tions and one request for a renewal that were still under investigation by the Depart­ment.

Borehole drilling in the Blantyre-Limbe Town Planning Area is only permissible under licence from the Southern Province Naturall\.esources Board, and the Depart­ment is the advisor to the Board 011. the granting of these licences. No applications for licences were received in 1961, however.

XIH. Conclusion

Although the year under review has seen considerable changes in the organization of Government, for the D(,])<lrtment it has been very much" business as usual", with some changes to cope with a shortage of professional staff and the training of Juniors for Senior Staff posts.

23

Those members of Lue professional and technical staff who have been directly concerned with the in-service training courses have borne the additional burden of teaching very willingly, and credit must be given to the trainees for their desire to learn and to both parties for the harn10nious way in which this section of the year's work has gone ahead.

This report represents the combined effort of all the staff and the writer is appre­ciative of their loyalty al1.(l <l"votion to duty.

BLANTYRE, March, 1962

24

E. W. LATHAM

Director of Wa/er Development

DIAGRAM ILLUSTRATING THE ORGANIZATION OF THE DEPARTMENT

RTERS ,

nirector of Water Development [

Executive Engineer CENTRAL

PROVINCE

, . I ------- ----------------Water Development

Engineer, LiJongwe

DRILLING SECTION

!-Senior------Groundwater Investigations / I Geologist I I I-BorehOle Drilling j I-Borehole Maintenance ____ j-BOrehOle

NORTHERN PROVINCE

\ . ---·-------Hydrologlcal

Assistant, Mzimba

1\1aintenance-I-Borehole Maintenance

I WATER DEVELOPII'IENT SECTION I

·-Water------Engineering Investigations--I-Enginccring Investigations

I Development I I Engineer [

! at HQ. No. 1 I-DeSign Office

! I [-Construction by contract

,

i \ I I f--DcpartmcntaJ ConstructlOn- -Dcparhnental construction-i-Departmental I Construction

HYDROLOGICAL SURVEY SECTION

··-Principal-·-~- -Hydrological Survcying-_ -Hydrological Sllrveying-- -Hydrological Hydrological Surveying Assistant -Laboratory

I-Hydrological Records

-Hydrological H.esenrch

I SECRETAIUAT Si<:CTION

"

__ secretary ----Accounts' Accounts -------1 Accounts Accountant I I I I -Stores -------\[ - -stores----------

j

-Stores

I , i-EstabllShI11CntMattcrs--'--I-Establishment Matters---[-Establishmel1t [ Matters

I I [ I TRANSPORT AND \VORI.{SHOP SECTION ! I

-MecJanical--j--Transport----- -~-Transport -- I-~Transport Supervisor

-Workshops

NOTE: Chain of executive responsibility shown thus ---------------­

Channels of consultation, advice, and assistance shown thus-,--__ ,

25

STAFF LIST 1961 .Senior Staff ,~nd Gn1dc HI Junior Staff 0-:1 the E~:t:\bIishrrH.'p,t

Director

Chief Executive Engineer

Mechanical Supervisor (1)

DraughtsJn,111

Secre tary / J\'CCOUll bIt t Departmental Assi:;t;mt (l)

Stc:lOgrapher Senior Storekeepers (2)

:\)),,1]~, 1:·;Tl~.-\T!\'E

E. \V. LATlL\':\I, B.se, (1::::\c.), ,\.c.G.I., ~LI.C.E., A.\LI.\V.E.

1Zctufnc(1 frunl vacation leave ;-lJ-··l·-\;j. F. G. CALE, B,:'iC. (L-;G.), :\,.)'I.I.c.Ii:., .. \.?I'U,\\'.E.

..'\c~jng 1)i(;;cto1" UJl~-il ;)U---],,,OI. J. AlcLEAN. On tcmporar:' "ppointmcnt; rc.:;igncd

;{ 1··-] ···0 1. T. E . .lU"ES. l{cLLir!lCd fUJln \';>:ati(,n leave 4---5-Gl. \'.'. H, Snn!!-->\\"iCE On Vd,Cil~-i(ln leave 22--2--·()J t()

:2J-D-Gl.

J. i\!. J\.-\.PIEl(, F.1': . .'\.5. Lcfi: 1)}1 retirement on Il-G·--(:ll, B. J. ClIIPOFYA, S,;niill' S·i".,:,rckl'-cper, CO. 1I1. ,Acting

DC1;;trUnc:1Utl Assi;,t;1l1 i L'01l1 12·-·()··~() 1. On va:~ltiCJll l(~"vc 1 0·_·1 o·-·n t tu 20·~·] 2·-·(;1.

:.Il::S A. Cou: ),1.. L. :\.-\;\1:\\\'.,\. On vacation 12(~VC from 1·-12~61. ]. J. l\.:\LES("), Clerk, CO. IT, .\c"ling Senior Storekeeper

L'om l·_·! ;2·--fi l. Onc post put in abeyance from 1·_·7-()l.

W .. \TD.; DEVELOP:"IlEXT GE~ER:\L

\Vater Development Engine::')":.: (:1)

F1rincipal Hydrological A~sist::\~it Computor

Hydrological A~sistants (7)

Hydrological As:jSL<ll1 t Trainel':; (()!l Training Pool E:;tablLhmt::n t) (2)

S~l1ior Field Assistant (on Tr'li:lin.,:< Pool Estabiisllment)

For8m~n Artisan \Vorks Supervisor (I)

B. ST.fnC~, r'-~:;c. (E~"C'.), .\.:'Il.LC.E., :\.:'I1.I.\\ .E., :'\UU-!.S., .-'l..:l.1.(s .. 'I..)j.C.E., C'lL\D.l.E,;'-. LcH ('0":1 vaCJtioil

leave pending t~;r;;lillati(ln of COllir'-1.Ct nn 28··;2--·01. ft. CONDlE, B,SC., A.R.e.S.T" A.:·].!.C.'-'

\Y. J. 1.. C:d.B;" .. \I·liI, L' .. sc., :\.'.J,I.C.E.

J. c. P;)':E, F.e,s., F.R.(;.S.

J. K()l:!,,\, DIP, r::-\o. (i'H.:\GUJ·:). On v<J.C:ltion le~vve l::···~···.(j; to 1 d---l.O···(j 1.

~"\. ! 1 . S l-!c\H .. \ '" I, ]) I !', E>; G. (lc\. l\:\cm). On vaca tin)) len.vo Lorn 1 ~';-l:?- .. (i j .

:·;L T. :!-31l.-\Tl:\. i.cft Ojl rcli;--cl11eni on ]:2 -2---Gl. ;\. J. \\':\HD I. l-L\zr~L;\j:;.J;,:. ()j1 v'\.calion ]e;)\'c J5<-}-,·Gl to :~1~-9.--(\l. ~\L J. l\i.\THEJ."-. ;\.l'~-"i\'cd i ;>-:~--'(il. '.1'\\,(; posts in abc) :nee.

T. n. l\::'d)Zl::--':JE. ProJ1"h'IL'd from 'L\. J1'l 0;1 J-~f)--G1. Vacntion l.:..:a\',,' i'j.--10---Gl tn ;j .. ··]2·-Gl.

J. )'L f>,\l\.THIDGJ<:. Pr;):Ij()lCd from 'fj\.. IrI on l·-·g·-·Gl.

E.l C1IlKW.\:\,"\. Prom()~c(1 from TA. II on l,--I-(H. n. CHIDOTliE J. 1\1. \VILSO:\,. On temporary appointment from

1-9--6] .

BORElIOLE :,\IAI:-::TE:-':;\NCE

Assistant Wells ?\{aintenance Ofiicer~ (:3) P. R. Lino\,\·:-,:. OE vacation lC;-1vc from :n --1 0---6l.

Senior Ceolu,:::j:';l

T. f.~. C!i.-\~.iLl-:\·

H. ANDREWS

BOhEgOLE DHILL'r-.;-(~

Kcw post 1 .. -7·-Gl. Post vacant. Geologists (2) (()ll seconcll11(;nt from Geo­

logical SUf\'ey Department) A. J. l\'IcLEAx, B.~;C. (.-\BEl·:DEE~-;).

Drilling Sn:Jeri:ntende~lt

Senior Driller Drillers (0)

I{. D. \VALSIL\\\', P .. se. (SO·1'T':-'I.) Secondment n:as<:,,_J 28·--2-0J.

One po:-:t n:!llOVC(; \\'iU~ z-;i'fcct j'rllrn J--'i--.;)l. \V. :\1. Ton]), "\.:\.W.O. Left nn retlrerl1cnt Ol, Q·-8-{l·f

p{)st ,j,l)oli:;ht':(l. E, (;. LE)': A. V. I:.\;-'::\j;'])o. H.ctUTllcll from vacation leave on.

2g .. ~G-,(j 1. 1~_, J. CUilD-II:\'C. On v:'.l,(:".tionlcQvc 1--2 .. -Gl to lO--4--·Gl. G. EOBEln::;. On \':~c;'lti(l1:1 leave 16·-1·-Gl to :,~7-G-Gl, S. \V. B!n;\vi:'~. On Vi"_lC<l,tion Je,tvc frorn 28--1:Z,-Gl. C;,).J . \.. :-.;,,1 TT. On v.:-:.catioi) lea.ve 4-0·-G] to 4- L!--G]. R. }-Ircrm::--:::;. Arrived J O~-11-61.

26

lv _1

TABLE OF BOREHOLES DRILLED IN 1961

: Rest _ i level

{o. District and Locality in ft. G.P.H. drilled: in ft. Remarks Depth in

Yield G.P.H.

Month drilled

i i I i Sp. Res. 'I Sp. Res. I . of lower Top and of wet i

K.Ohm wet zone Ohm. I[ Month of Geology Cm. in ft. Cm. survey

---~!~~---.------------i·----;--- - ·------1--- -.-.-------.-----.~------

layer bottom I zone K. ,

. -~ .. __ .. _._-.- _.-.,. __ .- .. _---, ---- ! '---

W 287 W 252 W288 Z 153

Southern Province Port IT Arald District.

Muona }.-Iission .. .. ; Lower lUver Farm Institute' l\fakanga Agric. St.ation Chiromo T()wn

Cltalo District A 7 Nanseta

jvIlanje ])i.~trid A 9 Mlava

\\[ 247 A Palombe ARian School

W 247 A 11

A 10

A 94 AM A 108.<\

A 108

J. 42 ,J ·15 A 2

W~112 L 280A A 21 A 31 A 3

A 109 A 32

A 33

A 34A A 34

E 299

A 5 A 6 A 12 A 92

1?a.1ombe A.si:::.·n S('ho01 Saidi

Xmnasoka

Saidi Tuehila Farm Inl;titnte lIkhanda. J\larkct

Mkhanda :'.Iarli:et Blant]/re J)·istrir-t l\fwanje I\iarket Msulupi Chitera Court

Zomba ])1:8t.rict Songani Asian School Chilwa APproved School .. Songani Asian :-:;chooj lifalosa Agric. Station Mingoli Forestry Station.

Chirullg,l, .T ali ltIarket

Raselcma

nlandawala Mandawala Kasupe District Balaka Township Supply.

Matola Malopa-Kapoka Mwikala I\fpunga

156 170 52

170

86

no 81

'/5 170

132

J60 210

(50

143

131 123 ]12

151 136 140 140 155

82 105

95

5:3 87

256

131 153 154 107

800 900 ?

1.000

670

540

l'~il

970 :Xil

150

1,200 1,000 Nil

700

600 34-0 480

Kil 900 690 900

1,000

1.000 1,000

600

:Xii 400

3,200

800 480 400 860

Jan. Feb. Feb. Feb.

March

April

lIray

June July

July

Aug. Sept. Nov.

Dee.

.Tan.

.Tan. Feb.

1farch IIIa-rcIl April July Oct.

Oct.. Oct.

Nov.

Nov. Nov.

June

July July Aug. Aug.

78 5

20 8

21

.,

10

55

7;) 33

33

26 ;W

3

13 9

25 45

31 48

30

18

38

33 75 65 18

Private i Agricultural Department, Hand-rig. Agric. Dept. ' Chiromo Rural Area

Board

N .. A. Chima.Iiro

N .A. 1I1klmnda

Abandoned in b0111ders l\L\V.T.

~LW.T. Dry. N.A.l\lkhumba. See:

.<\.94 X.A. Mkhumba

:N .A. 3Ikhumba . Social Development Dept.: Abandoned in boulders '

1\ .A. l\'Ikhanda :N .A. 3-I!dlanda

N .A. Kade,ycrc 1\ oil.. Kadewcre N .A. Chitcra

Dry. 1II.\Y.T. See A.21. Adjacent to L. 280 M.W.T lILW.T. Agricultural Department M.W.'!'.

N.A. I1Iwambo N.A. Chikowi

N.A. Chiko-wi

Dry. N .A. Chikowi N .A. Chiko\vi

10". M."\V.T.

N .A. Msamala N .A. Kawinga N.A. Kawinga N.A. Kawinga

Alluvium Alluvium Alluvium

1.2 \ 20--200 + 8.3 . 10-60

No 1 Depth

Alluvium No Ge!ophysical

\Veathered basement com­plex gneiss

..:\_lluvium over basement complex gneiss

Sand and boulder beds Sand and boulder beds

33

30

1,160 1,160

Sand over basement gneis'3 350 Sand over basement com-

plex gneiss 16 Sand and gravel over gneiss 2ft Sand and gravels 35 Alluvium <"nd boulders over

syenite 1,080 _Alluvium over syenite 1,080

Weat.hered \Yeathered Alluvium

gneiss

basem:mt gneiss basement gneiss over basement

Basement complex gneiss Alluvium , Basemcment complex gneiss i Out·wash gravel deposits ' Decmnposed homblcndic

gneiss Alluvium Alluvium and basement

gneiss Alluvium and basement

gneiss Basement complex gneiss Basement complex brneiss

Alluvium and basement gneiss

Alluvium and limestone Alluvium over flinty rock Alluvium Alluvium and basement

gneiss

25 380

530

300 15 24 5.8

29 18

320

380 85 85

13 14 16 0.88

16

10-40

10-40

I 20-80 , 20-80

10-40

20-60 10 ..... 60 10 .. 40

:W-140 20,··1'10

20-40 10--40

10-40

10-40 10--50

0-40 10-40

20--60 10-60

10-60

10-60 20-40 20-40

10-100 10-80 10-60 20--200+

10-60

1.2 0.92

Probe

Survey

[,.8

0.77

5.S 5.8

1.7

1.8 2.8 1.9

5.4 5.4

1.3 1.9

2.7

2.5 2.0 2.7 1.9

3.2 1.0

1.6

1.9 1.3 1.3

1.0 0.74 2.7 0.88

4.0

Dec. 1960 Sept. 1960 Dec. 1960

I Feb.

:Feb.

Sept.. 1960 Sept. 1960

Feb .

:Feb. Aug. Aug.

Sept. Sept.

Feb. 1960 Feb. 1960

Jan.

Feb. Ii'Iay 195(-; l\1arch April

Jan. Sept.

:May

l\-fay 1\-lay May

Jan. 1959 Feb. Feb. Feb.

Aug.

TABLE OF BOREHOLES DRILLED IN 1961-(Continued)

Sp. Ites. of lower Top and

i layer bottom zone K. 1I1ont·h Depth Yield iK.Ohm. ,,,.et zone Ohm. of

:\'0. Distrid and Locality in ft. G.I).H. HCill2.-rks Geology t Cm. in [t- Cm. survey

A 05 Kuwa'v\·a 96 aoo N.}\.. Knwinga Alhn:ium, sandstone, and gra.nite Xo Depth Probe July

A 96 KllLhernba 187 650 Dee. 82 N ./t. 1lIsamala Alluvium No Depth Probe SOY.

A ~);3 Ndan<l<11a. 69 800 Dec. 12 l\.A. Kawinga 13ascment. gneiss 850 10-40 J.2 Aug. A 56 Pioli 137 480 Dec. 50 N.A. Kawinga Alluvium and b:sement

gneiss 13 4D-$0 3.1 .Tune Fort J ohnslon District

J 26 Maka.njira Court 108 890 Sept.. 18 N.A. :;}Iakanji;·a Alhlyimn ::\oi; Resolvable Oct. IG5D J 27 l\1aiemi[l, 120 1,030 Sept,. 0;3 X.A.1Ial:,tlljint --' .... ll~ivimll Xot Resolvable Oct,. 19;}~)

J 25 T~:LDw~~ta 130 900 Serlt. :)0 )i .A .• TaJas! Aliuvium )ioi ltcsolv[1ble Oct .. 1%9 J 22 2'tlitenganya 175 720 Oet. 80 N.A. ,Ja.i;,si Alluvium Kot· H_csoiya.blc Oct. 10sn .T IS Xdiuli J 50 800 Oc' .. Z;') N.A .. ){l.lasi j.liuyium 0.8 J 0-200 + o.c~O Octo. 1!)59 J 1~ X(iiuli

Centrai ?ro~i~cc 200 Si! Soy. Dry. ?·:.A. ,Tal as! Allnyimn ]() 10-200+- 10 Oct. 1959

Lf!on(fwf. District A It) Ali ;,.r:-dinde 115 ,SO )'I;,reh 40 X .. .e\.. Cititukula \Vea_tllercd biotH.e gneisS G.;} 'i-O-ZOO (i.3 :l:Tarch A 10 Kyankw<<- 7& 720 XLu-ch ;:;., :\".A. ]{;tblidula D:llnbo <1.-nd ,tll1rdal deposits' 0.27 GO-200--+- 0.:27 lI-Iarch A 1;") 'l'saba-ng:o Court JJG 4S0 ~\pril f-~ ::r\.)·c. Ealumbu \Xcathered biot,ite gneiss . {$:30 10-40 3.1 I\larch A S3 Chirl"ll't.u ;3:;\ 720 -'.lay :3:2 X.~\.. X:ll'-lmbu vVeathered biotilc gneiss 6:? (H30 n A_pril

i'v A 14 Liklilli _Farm Illst.it'-l~e : . 127 1S0 )I:,.y 70 ?>f."\Y.T. \Ye;.\thcred bicLite gndss G.S 20-200+ G.B ::'o.Iarch en A 25 Chi~-:!h:,-y() 106 'ISO .} illlG 20 X.A. I~hJili Dambo deposit-s . 02 10-40 (JAG J;_p-ril VY J ~;3 Chil'·{:k. (X; '1-00 ,TIme ZO S .A. )l<~_~:,lli \Veat..llercd (m.sement gnci~", :";ot ResolvabJe A_ug. 1059 A 22 l\;l)·::i'.\·.'1\,·,1, \)7 7:W June 18 S .. -\.. J(;licmi.>a. 'V{~;1.Lllercd qu<")..rtzitic gneiss 160 20-40 0.00 April "i J '2.;~ Chip'.Yii,lij-'a I(W 460 Junc 25 N . ...-\.. :E:hOll~OIii v~' e<tLhcrcd basement l.;:rtciss GO lC-SO G.7 Aug. InS\) A 18 ~vIazcl,g(;ra: COlirt, ~;O 1,200 .July :2{; X.A. },lazengem \"Cca!-ilcrec1 b::u;cmcllt, !inciss ::::0 60-200+ :2.1 ~"Tarell /l 24, 1L,lazv., bO 150 Aug. ~(! 1'\' . .1\. }fazengera. Dambo deposits ,- rlQ 10-·10 2.0 April

\":)7 12,1, l\yundo S7 720 Aug. :!o K.A. i.-'"ialunibll VI: c:,.t.hcred baSCfncnr. gneiss lB 10··JOO , .. 0 Aug. 10;)0 V{ 1:2'.1 Chadz,~ Sehool lOO 1S0 Aug. iO X ... L Cll:~dza. .i)ae-)bo deFosits :W 0-40 2.~; ~\ ug. 1 H,)D

])ou·a. j)·istrict. \y 280 ?\sa(~ZiJ 150 Xil Fe]). Dry. X.A. Earonga AllU':IllIr! 7.5 10-100 :3.2 -:";-oY.10GO W 2S2 )Ipanje 110 320 Feb. (;0 :..; .,,\. Clliwere Alhl"l:iu!ll 3G {)-40 1. 'J :\ ()\ .. HH;O J~3:;:7.A :_~<lUnm. -Police 'J~iw,s l;~O 1,500 N.!:n:b :.H ~\.dj:-:CCld·. to L. a:)7.

),1."\1,'.'1'. .Allwdum 0..10 GO-2eil -~- D.·l(J ,-\ ug. l\);>o W ~no Xdyn_p;:li.,;i 110 ;),10 .} t:I:: ::?OO X.~\.. Dzoole ]);:.mtH) deposit.s. :3.0 JO-~OO - ?fJ ];eb.

\V:309 .xrk()ta.m{) 127 120 ~\ ';g. /.) ~\ ."1. DzooJ\> . H,,;i;ement gneiss c(>,j1l'icx 320 ] (}-,W :U; Feb. \Y:311 Clligoma 1:->5 900 ~i..1(g. :)1 X.A. Dzoo!e D;"tmbo dcx;osits :l.0 40-~WO-i- :3.0 FeiJ.

"V 31 ?\::!.1wili 145 gOD Aug. :3 1i: N.A. Dzoole Bas.ement gneiss complex :\0 Depth 2ro()c Feu. !\'a..wn[1?}. Dis{;'i~l

\y 30;3 Lodj"v<1 Trading CBntre 106 90G A,[:<,c):: 82 N . .:\. :K_<tlaluma "We;;.thcrcd (jlmrt;zit.e 0.60 20-200+ 0.60 .Tan. W 308 Kaslm~pl Poliee- SbUon JOG 220 _April :3~ 1\-"1.\\'.'1'. B,;.:;;(~mcnt complex g!lei~:s 92 10-40 4-.H Ecb. W:)06 K,wala 110 900 :-icpt.. :33) ?\./L )1 w:'.se ~\llu'."ium 13 10-20 0.70 I"cb. W 305 Chn.im<1 103 900 Sel)L. 35 );.A.31\\"<::.se _Aliuvil.lm "ad '.veat.hered

gneiss 46- 20-80 8.0 Feb. W 304 ClJ.a.loam:,c~::::mbe 126 Nil Oc-.t. Dry. X . .c\.. Jl.Iwase. Sec QuarLzit,e :n;d leucocmtic

A. 118 gneiss 40 10-40 4.4 Jan. A 118 Ch.aJoam:::.t.embe fl8 120 Od. 45 N .A. Iifwase Dambo deposits 72 10-60 3.8 Oct. A 119 TI"fbuzi 110 900 Oct.. :~5 X .A. ?1\vase Bascrr;.ent complex gneiss 22 10-60 3.8 Oct. A 134 Xiw,11a 00 £lOO Oct. 25 K .A. I'Iwa~c;e Y.'eathered basement gneisS 220 10-60 1.1 Aug. 1959

"" <0

TABLE OF BOREHOLES DRILLED IN 1961-(Co-ntinued)

"I : Sp. Res. 'I Sp. Res. i i of lower Top and of wet I

Rest I i layer bottom zone K. Month Depth Yield Month level llemarks! j K.6hm.' wet zone Ohm. of

~i __ District and Locality in ft. G.P.H. drilled in ft. 1 ________ ----1---- Geo~~ ____ i-~1 in ft. Cm. survey

A 114 Mpazi 140 900 Nov. 26 N.A. Mwase I Basement complex gneiss '1,430 11

A 115 Mbambo 95 240 Nov. 26 N.A. Mwase Basement complex gneiss 97 W 307 Ngwedi .. 90 900 Nov. 21 N.A. Mwase I Fault rock 660 I A 117A\ Kasungu Asian School 63 60 Nov. 36 Schooisitechanged. I '

Abandoned M.W.T. Clay J 36 i A 117 Rasungu Asian School 137 1,330 Dec. 36 8". M.W.T. I Clays, boulders, and base·: I

1

ment gneiss '36 , Northern Province . I Mzimba, District i 'I

W 292 \ Edingeni 148 540 Jan. 28 N.A. ~l'mbelwa ' Deeply weathered basement;

I gneiss t 1,900 ,

W 295 Thoza .. 175 900 Jan. 35 N.A.1'tfzukuzuku Quartzt.ite and pegmatites i 24 W 273 Mbawa Agric. Station 155 130 Jan. 29 10" and 8". Agric. Dept. Deeply weathered basement'l" I

gneiss 340 I W 297 ! Echiyeni 165 900 Feb. 38 N.A. Mzukuzuku Deeply weathered br~sement,

I p- ! 17 W 298 l\fzomo 150 530 Feb. 28 N.A. Mzukuzuku Deeply weathered basement I T I

gneiss ~ No W 293 Nkosikazi 160 440 Feb. 38 N.A. Mzukuzuku Deeply '''"eathered basement I

gneiss ! ~o W 294 Dimi 115 530 Feb. 16 N.A. Mzukuzuku Deeply weat.hcred basement l

l gneiss :.Ko W 302 Katundu 169 900 March 35 N.A.I1fziknbole Deeply weathered basement

gneiss ! W 300 Hora Farm Institute 200 330 April 29 10" and 8'"'. N.A. Chinde Dambo soils over basement

gneiss W 265 Mudiri 150 370 April 64 N.A. :Mtwalo Clay W 264 Dolora Nyajakwa 110 220 May 28 N.A. Mtwalo Quartzite W 262 Enukweni . 210 320 J·une 45 N .A. Mtwalo Basement complex gneiss W 78 Kamondoma 106 800 June 41 N.A. Mtwalo Basement complex gnciss W 259 Ludzi School.. 119 Nil June Dry. N.A.1'Uwalo. See

A.SS W 290 Rufu IVIfunika 36? June ? Hand~rig. Agric. Dept.

N.A. Chinde W 289 Yakobe Ndeyu 28 Aug. 9 Hand~rig. Agric. Dept.

N.A. Chinde A 83 Mpelapi 55? Sept. 28 Hand~l'ig. Agric. Dept.

N.A. Mtwalo A 85 l\Ipelapi 56? Oct. ? Hand-rig. Agric. Dept.

N.A. Mpcrembe A 87 }i;longeni 50? Nov. 13 Hand~rig. Agric. ilept..

N.A. M})erembe A 88 Ludzi School. . 120 Nil :Nov. Dry. N .A. 1I1twalo

W 79 Vongo 155 530 Nov. 90 N.A.lI-Itwalo Z 157 Kafukule 42? Dec. 5 lIand~rig. N .A. II1twn.lo

W 86 Kazuni .. 67 Nil Dec. Dry. N.A. Mtwalo Karonga District

A 89 W.N.L.A. Fort Hill 135 260 Aug. 15 Private W 70 Ibanda 160 440 Aug. 71 N.A. Chungu W 71 Chendo .. .. 155 Nil Aug. Dry. N.A. Chungu A 90 W.l? School, Karonga 200 880 Sept. 130 Private

W 222 Mwabanga 105 530 Sept. 48 N.A. Kyungn W 221 Mwangweo 104 440 Sept. 38 N.A. Kyungu A 91 Katalolo . . 110 1,060 Oct. 26 N.A. Kyungu

W 68 Nthalire Court 162 1,060 Oct. 26 N.A. Nthalire W 69 Chiunti 96 440 Oct. 40 N.A. Nthalire

Rumpi District W 258 I1 Bumba 170 260 I July 76 N.A. Chikulamayembe

Basement complex gneiss

Dambo deposits

Dambo deposit~

Dambo deposits

Dambo deposits

Dambo deposits Basement complex gneiss Weathered basement gneiss Dambo deposits QU2.rtzite

Sand 'Veathered basement gneiss Sand and basement gneiss Alluvium over quartzite Alluvium Alluvium Alluvium Alluvium Alluvium over basement

gnciss

Raroo sandstones, grits, shales

7.0

7.0 49 74 :?7 ~20

480

80

13

370

370

600 590 31

Ko M

Not Not

5.9 2.0

No No Ko Not

720

25

10-80 20-60 10-60

10-80

HHIO

50-200 40-100

10-40

2{}--200+

Depth

Depth

Depth

20-200+

20-200+ 10-4(1 10-100 20-100 20-60

10-40

0-50

0-20

10-40

10-40

40-60 10-60 10-60 ,

Geophysical! 40-60

Resolvable Resolvable

20-100 20-200+ Depth Depth Depth

Resolvable

10-40

10-70

7.1 5.1 3.3

8.9

8.9

9.5 16

1.7

17

Probe

Probe

Probe

7.0

7.0 2.0 ':>.2 4.7 1.1

2.4

20

1.5

1.8

1.8

3.0 3.0 3.5

Survey 3.4

2.9 2.0

Probe Probe Probe

3.6

8.3

Oct. Oct. Feb.

Oct.

Oct.

Dec. 1960 Dec. 1960

Nov. 1960

Jan.

Jan.

Jan.

Jan.

Jan.

Jan. Sept. 1960 Sept. 1960 Sept. 1960 June 1959

Sept. 1960

Dec. 1960

Dec. 1960

July

.Tuly

July July June 1959

June 1959

July June 1959 June 1959 July .Tune 1960 June 1960 July .June 1959

June 1959

Sept. 1960

Name of StatioN

;VIimosa

Chisombczi

Naming' om ba

Bvumhwe

Chilelm

ChikWi\.Wil

:\'1cttope

Nchcu

Zomba

;\lonkey Bay

Chip ok a

S<'Llima

Chongoni

Mzimha

Mzuzu

Karonga

Deep Bay

ji;VAPORATION AT SELECTED STATIONS

1:;1 November, 1960 to 31st October, 1961

i _

DraiJl.­al:(e

Area

I.E

2.B

3.1"

I

I i E!ceution i a/)o,:e : .1i .. ';L jI. I

I I

3,500

2,:");20

1';::;30

3,1·10

J ,:370

Pa.n E"l,,'apo}'aLio.'l i J/ inches

l\.G/'Iya--lypc /,((11 Class-A -I)'/h' j}all

1900/(j I

U~.2a

0".88

G3.18

O:l.O3

40.08

;")7.66

f)fi.;32

82. ~i 8

78.78

GG'()7

;,)1.i,)8

99.00

\)2.04

Long­fe1'rn IIWfln

86.89

09.24

72.0G

71. I I

32.1 ;)

01.39

lo-i.2G

SO.21

97.46

9:~.57

Lang­tcrm

1(1)0/61 I mea'i/·

"1 -89.2, i 8::LO~*'

01.021 "".8G

GO.·lO 67.GB

JO.20

!)J. :38 ,;8,22

91.49 100.01

is.G8 'C).56

75.1 Z 8,;.58 I

9;').:33 93.88

88.10 89.59

Period of Record

in :yea1's

8

4

;3

JIJ

2

G

10

'i

9

9

4.13 I,G70 72.26 81.84 68,81 78.15 10

,'.B 4,500 67.47

7.A 4,450 84.52 [Jl.24 80.76 87.32 10

7.D 4,160 57.28 64.11 54.21 60.87 10

8.A 1,,570 9:3.01 88.15 90.90 84.30 9

8.C 1,560 M.41 90.41 90.83 9

Kota Xota .5.13 1,560, 81.48 . ' .77.80.. .. I 1

~_~~?~l;~Sj~;~ __ ·-=-=:==I=+r~I-·~:~~~:= =g£='~:-~~'=I~~~~ -~-~~=I==~= * Actual Class :\ pan measurements, all other Class A pan figures being calculated from

measurements made with Kenya pans.

30

Liwonde

IVlatope

l\Llganga

Chiromo

Locfl/ion

SHIRE RIVER FLOW INFORMATION

R.G.S, Number

IIBII

I/P/2

I

i"1i'~imuiu I Ai axim1JI7I I~low '\ }</ow Cusecs-r CusGcst

---,-,----.-.-~- .-------.-- .---.~ .... 4,4.!)O ' 2:),G7;,)

4,880 2;1,71;3

,He({;i

AnNual jlow

,1C'i'e-I~ctt

1,487,0;')3

7,43!,21O

P::/'iud 0/ record i;/ y,lurs

JUGGI51 Total jhw

A [rc-feet

12 O,761,7JD

I 8 I 6,947,448 .. "'-"'-'''' . __ .. -- .. -.- .. _-_._._-....... _............... ......... .... _--_....... .

I/L/6 4,580 47,600 10 7,507,61~ ._, ........ _----IIGII I .. ·4,000* 46,62H J4 7,497,030

The above flgnres do not take into account the alteration in regime during the period when the river wa~ blocked by the Liwonde Band, t Observed flows from start of records until :Ust October, 1961. 4< Estimated reverse flow due to H.iver H.uo backing up River Shire.

31

River

SOUTHERN PROVINCE Lirangwe Mwamphanzi .. Likabula (Lower) Naperi Mudi Mapercra Tangadzi East !olasenjerc Tangadzi West Mwanza (LO\ver) .. Mwanza (Upper) . _

G.:J Wamkurumadzi t~ Lisungwe

Rivi-IUvi Rno Rno Rno Tuchila Lichenya Nswadzi Nswadzi Nswadzi Luchenza Luchenza Kwakwasi Sombani Mlunguzi Mlunguzi Weir Mlunguzi Weir Palombe Likangala Namadzi Domasi ..

Location

Matope Road Nsanje Village Chikwawa .. Chikwawa Road Mudi (above dam) Mafume Village N gouge Village .. Chiromo/Chikwawa Road Nyamalambo Tomali Village . _ .. 1\'fwunza/l'.E.A. Border Road .. U IS Chileka/Mwanza Road Moffat Village _ . Rivi-IUvi Govt. }i'arm Sankulani Mlanje RUG Estate. Chionde Mlanje Chipungc _. Magombe N yasa Tea Estate Plywood :Factory Limbe/Nansadi Road Blantyre/Cholo Road Paloni Hill Zomba .. Zomba Plateau Zomba Plateau Rigola Village .. LimbejZomba Road .. Limbe/Zomba Road .. ZombajLiwonde Road

I R.G.S.

I~ I I 1/0/1

I l/E/l I I/E/2

'lllE/4

l/E/IO l/F/l I/F/2

I I/F/3 1/G/4 l/K/l 1/K/3 1/M/2

. 1/0/1

Il/R/3 1/D/5 1/D/9 1/D/22

i 1/Dl3 I 1/D/10

1/D/12 l/D/17 1/D/16 1/D/23 1/D/20 1/D/24 2/A/2 2/B/2 2/B/8 2/B/11 2/Il/4 2/B/5 2/B/6

i 2/0/1 I

RIVER FLOW INFORMATION 1st November9 1960 to 31st October, 1961

Oatch­ment area sq. miles

78 117 218

8 3

25 19 8

162 630

35 205 461 300

1,869 78

213 540

28 147

37 22

198 102

26 280

10 7 3

537 26 11 30

':1' otallNow 1960/61 Acre-feet

48,752 95,814

111,318 6,859 1,912 9,S05 7,G2:7 2,SDl

25,306 22,5;)0

135,594 200,911 374,147

1,525,307 323,23:3 583,734 312,099 181,618 67,451 34,993 11,330

148,884 56,400 16,826 76,384 21,560 16,529

7,088 497,t)25

46,559 8,928

69,051

Rtm oJf per sq. No. oj days oJ mile in acre-feet no flow j1Jean

Annual I!'low

!----,---- No.oj ---- ----: Min. l?low i j Mean Yearsoj j Mean i in

i Acre-feet 11960/61; Annual Record 1960/61; Annuali cusecs* : ---1------

32,421 60,717 I

60,267 I ;),648 1,640 i

14,829 i I:3,130 '

3,724 Data 77,353 28884

129:624 176,093

i ]J~~:M~ 370,466 578,446 208.486 144,431 114,487

37,352 15,310

123,229 53,391 15,75B 51,636 18,033 14,144

5,998 390,192

28,544 6,701

47,638

625 819 511 8f)( 657 392 401 :361

Kot 40

644 661 43G

1,247 81()

4.144 2,741

578 6486

'459 946 515 752 553 tj47 264

2156 2;3Gl 2,362

927 1,791

812 2,302

416 519 276 706 567 593 69J 466

available 123 825 632 382 420 771}

4,750 2,716

386 5,158

779 1,010

69($ 622 523 606 179

1,803 2,021 1,990

727 1,098

609 1,588

10 9 9 8 o 9 S S 7 9 7 8

10 8 8 S 6 9 8 8 , 7 7 7 9 9 9 6 5

12 9 9 9

29 5

39 KiI Nil Nil Nil Kit 341 210 Nil Nil Nil 25

Nil Nil Nil Nil Nil Nil Nil Nil Nil Nil Nil 58

Nil Nil Nil

49 Nil Nil Nil

40 Nil 26

NU Nil Nil Nil .xil 273 150 Nil Nil Nil

15 Nil Nil Nil

1 Nil Nil Nil Nil Nil

1 Nil 64

Nil Nil Nil

46 Nil Nil Nil

Nil Nil Nil

0.05 0.002 0.4 2.~ 0.2 Nil Nil 1.5

15.0 4.5 Nil

65 7.5

25.0 Nil 3.0

17.0 5.0 2.0 Nil Nil

0.41 Nil 0.10 2.3 LO Nil 0.5 0.30 0.50

* Minimum and maximum flows shown are the lowest and highest recorded flows since records commenced.

E= Estimated.

Maz.I!'low in

cusecs*

7,600E 4,190 6,600 4,800

141 4,000

13,750 700

3,240 4,700 1,415

13,700 20,400 21,150

190,000 30,000E 33,OOOE 25,OOOE 14,OOOE 15,250E

3,OOOE 2,517 8,000 5,200 3,700 2,600

450 346 230E

11,360 4,800E 2,500 4,000

River

CENTRAL PROVINCB N adzipokwe .. Namikokwe (Lower) Livulezi Naga/lnglya Nadzipulu Linthipe Lilongwe Lingadzi Bua Bua.. _.

NORTHERN PROVINCE e;., Limpasa to Luweya

South Rukuru South Rukuru Mzimba Lunyangwa. Lunyangwa Kasitu Kasitu .. Runyina Chelinda Luviri .. North Rumpi Muhuju Lura .. Kaziwiziwi Kambwiya North RukuIu Wovwe .. Chitimba Nyungwe Songwe ..

Location

Ntakataka. (Mua Mission) Escarpment Road to Dedza. NtakatakaJDedza Road Near Ntakataka Near Ntakataka Salima .' Hlongwe Town LUongwe/Salima Road Hua Bridge .. LiIongwejFort Manning Road

IAmpasa Dambo Luweya Ferry Road Pwezi, Henga ValleY Chimsewezo Mzimba by-pass road Ekwendeni IVlzllZU Causeway Njakwa Edllndu RllmpijChisenga Road ~ll!ilpi Ngonga .. .. NjakwajIsivingstoma Road Njakwa/Livinstonia Road Lura .. .. Njakwa/Livingstonia Road Near Nchenachena .. Mwankenja .. KarongajDeep Bay Road RarongajDeep Bay Road Nyungwe .. M wangulukulu Village

RIVER FLOW INFORMATION-(Oontinued)

1st November~ 1960 to 31st October~ 1961

i R.G.S. I No.

1-I I 3/E/l , 3/E/2

I 3/E/3 3/F/2

'13/F/3 4/B/l 4/D/4 4/E/l

I 5/D/2 I 5/E/2 , I 6/]1'11 . 6/F/2 : 7/G/14 I 7/A/3 I 7/A/4 1 7/D/3 'I 7/D/5 , 7/D/7

'I 7/D/4 7/F/l 7/F/2

1 7/G/13 i 7/G/2 I 7/G/3

1

7/G/8 7/G/15 7/G/ll 8/A/2 8/C/2 8/0/3 81014 9/B/l

I I I I Oatch- \

1

- ment ~7ea sq. miles

i I 1 ,

! 70! 54

191 25 86

3,266 730 321

2,722 137

106 900

4,577 362

37 190

10 804 283 346 188

20 117

29 7

61 43

753 134

11 155

1,567

Total Flow 1960/61 Acre4eet

15,319 42,144 84,999

9,631 i 68,399

739,182 158,206

65,845 384,809

56,721

105,453 1,055,526

424,997 20,982 37,735 88,617 19,923 99,719 !

21,529 ! 111,176 80,946

9,728 184.253

n;lOO 91,448 56,680

210,955

28,199

1,355,177

" I I I i Run off pe7 sq. I I No. of days of

Mean \ mile in ac7e-/eet I no flow Annual .----,-----' No.oj ----1---- Min. Flow Flow \ i Mean ! Yea780j : Mean in

Acre-fce~\, 1960/61 I Annual 1 Rec07d '11960/61 I Annual cusecs*

13,348 38,341 65,368 8,879

52,315 774,703 160,839 61,419

415,155 34,770

90,798 745,909 517,650

42,282 33,788 71,950 14,562 99,245 59,015

157,599

9,643 156,823

12,161

66,063 45,601

279,095

75,095

974,536

219 780 1 445 385 795 226 i 217 ' 205 141 414

995 1,173 ,

93 i 58 '

1,020 466

1,992 124

76 339 431 486

1,575 383

Station 1,499 1,318

280 Station 2,564

Station 865

191 710 342 355 608 237 220 191 153 254

857 829 113 117 913 379

1,456 123 209 455

482 1,340

419 Closed 1.083 1,060

371 Closed 6.827 Closed

622

7 2 2 2 4 8 8 8 7 6

8 8 4 5 4 7 8 5 6 7 1 3 8 2

8 8 8

5

8

Nil Nil Nil 48 Nil 28 Nil Nil 72 19

Nil Nil Nil 78 Nil Nil Nil 39 85 Nil Nil Nil Nil Nil

Nil Nil Nil

Nil

Nil

Nil Nil Nil 44 Nil 28 2

Nil 40 16

Nil Nil Nil 40 Nil Nil Nil 35 55 Nil

Nil Nil Nil

Ni! Nil Nil

Nil

Nil

0.20 0.3 0.01

Nil 2.3

Nil Nil 0.1

Nil Nil

6.5 120

56 Nil 3 0.5 1.0

Nil Nil 20.0 40 1.8

46.0 1.5

23.0 11.5

7.0

1.3

102

=$: 1liniumum. and ma.:J:;:imum flows mbown are the lowest and highest recorded floWS since records commenced. E = Estimated.

Max.Flow in

CUSec6*

2,700 1,800E 2,900E

260E 4,000

34,250E 8,650 6,000E 4,688 1,500E

3.172 23,000

3,600 1,2ooE 2,500E 6,000E

190 2,600E

13,000 1,600

600E 250E

3,000 250E

1,300 465

14,000E

1,000E

7,700

Month

November December January .. February, , March April May June July August September October "

111 ont /i

November December January Februarv I\'1arch . April Mav Ju';e July August September October

111 on111

November December January .. February .. 1Iarch April !\'la )' June July August September October "

Monthly Flows at Selected Stations SOUTHERN PROVINCE

Ruo AT SANKULANI R.G,S, I/D/5

Mean Flow in ",secs, 1960/61 flow in

--------'-.----- cusecs jor last 8

Jl1axinuun Alini'lnmn J\1ean

2,390 5,980

20,200 16,800 15,600 7,600 3,389 3,400 8,000 6,100 8,200 1,720

108 262

1,607 2,08:1 1,900 1,344

65U 307 599 ,13;,) 29" 209

313 1,294 5,063 4,518 5,392 3,002 1,282

582 1,375 1,323

830 465

707 1,965 4,231 4,929 4,092 3,707 1,336 1,002

893 696 481 319

CENTRAL PROVINCE LILO~GWE AT LILONGWE TOWN R.G.S, 4/Dj4

Flow in cusecs, 1960/61 '------1----------llIa.;dnnu1t 1 ilh'l'lh-nwn lvlea.n-

. ,_ .. _-_.----._---- .... _ ...••.•.. _.,- -. - ----.. - •..... - -_ ..•.... _-"--99 0,2 12

228 3,5 45 758 83 288

1,143 88 437 1,506 381 1,032 1,263 206 536

230 73 144 75 55 64 55 38 45 37 16 23 16 6 II 5.9 0,5 3,3

Mean flow in cusecs for

last 8 years

------~.--

10 126 277 918 708 377 148

65 42 27 15

6

NORTHERN PROVINCE SOUTH RUKURU AT PWEZI R.G,S, 7/G/14

34

1vfean Flow in cusecs, 1960/61 flow in

.------ ------ --.----,- cusecs for last 8

ikI aximurn. JVlinirTZum. Mean years

123 75 98 85 639 72 205 279

1,099 170 531 839 1,708 658 957 1,382 2,059 1,012 1,575 2,232 1,970 1,120 1,425 1,760 1,080 560 727 702

557 420 482 461 480 362 401 341 359 278 319 258 275 178 225 178 177 110 144 ll9

SUMMARY OF SILT FACTORSt

,

I Estimated

Silt maximum collecting

1960-.011 Aiean Period daily

H.G,,','. area in anJH!al of ,'ceard laad 1>n

No. River sq. miles Factors I Factor in years tons;~

-~~. ._---,-'---------.. ' -- .. _,--- .. _--- ... _" .-"._--.. - ---,--.. _"'--' _.'-' - ---.-- ._- .. _-----_._- -_._---_ ... _ .. ---"-'--l/C/l Lirang\ve · . · . 78 2.77 I 2.0f) 10 50,000 , I/D/2 Kwakwasi 26 0.89 0.65 9 8,000

1/ j) /3 Tuchila .. 540 1.45 1.37 III 60,000

I/D /5 N.uo 1,869 0.69 0.,,3 ~ 900,000

1/!) /ll l~uo · . 'i8 0.05 0.07 8 18,000

1/D/I0 LiChen'ya · . 28 0.09 0.06 8 2,600

1/D/12 Nswaclzi · . · . 147 0.51 0.42 7 18,000

l/D/l G Nswac1zi · . · . 22 0.50 0.54 7 8,000

1/D/17 Nswadzi · . 37 l.l,l 0.81 7 18,000

1/ D /20 Luchenza · . 102 1.15 O.S{) 7 17,000

1/1)/22 E.uo · . · . 213 () .12 0.13 7 33,000

I/D/2:J Luchenza · . · . 198 2.84 1. 8(; 7 58,000

I/E/l Mwamphanl.i · . · . 117 1.48 0.80 9 30,000

I/E/2 Likabllla · . 218 0.82 0.60 9 25,000

l/E/:J Mudi · . 7 Station closed 0.93 8 3,200

I/E/-I ;\'aperi S 0.71 1.27 8 10,000

I IF/ j :VIal)erera 2[) 0.G4 0.57 9 8,000

1/1'/2 Tangadzi East ID 1.26 1 . Hi) 8 30,000

1/1'/3 l'vIasen i ere · . 8 1).51 0.54 8 '1,000

! /G/~ Tanga<lzi \Vest ];32 ::Jo Data J.31 7 9,000

I/K/3 M\vanza 3b 0.3i) 0.28 7 4,800

!/K·fl lVIwanza 630 o.on 0.10 9 ;;,000

I/M/2 \Vamkurumadzi · . 205 0.18 0.13 8 4,000

1/0/ 1 Lisung'\ve 461 0.58 0.44 10 32,000

I/I{/3 Rivi-Hivi · . 300 2.55 ],23 9 100,000

2/A/2 Sombani · . 289 0.03 0.02 10 250

2/B/2 1'1'1lunguzi · . 10 0.13 0.08 10 600

::/B/,j Palombe 537 !.l3 1. Of) 10 no,ooo 2/B/,-, LikangaJa · . 26 0.64 028 10 5,000

2/B/(j Namadzi 11 0.27 0.39 10 8,000

2/B/I0 Palombe 26 0.16 0.17 6 1,000

2/C/I Domasi 30 0.36 0.11 10 12,000

:l/E/l Nadzipokwe · . 70 0.67 0.66 4 9,000

:1/1'/2 . Namilwkv\'e · . 54 0.43 0.35 2 6,000

:)/E/3 LivuJezi 191 1.45 1.23 2 18,000

:1/F/2 Nakaingwa 25 0.25 0.16 3 600

:1/F/3 Nadzipulu 86 0.71 0.55 4 9,000

4/ Bjl Linthipe · . 3,266 0.42 0.64 7 '100,000

4/1l!,1 Lilongwe 730 I 0.41 0.15 8 4,500

4W./! Ling-adzi 321 0.16 0.13 7 8,000

[./1)(2. Bu~ · . 2,722 0.02 0.04 7 1,090

!5fl)I:~ ;lHi Ii 89 0.07 0.20 4 1,000

5/Efl Namiteic 6" O.!l O.ll 5 3,000

ri /I~ /,1.. Bua 137 0.12 (UO 6 1,800

I

35

R.C.S. No.

-'·-'_'_0-_'

6/F 1I G/F/2 'i /i/3 7/D/3 7/))/4 7/D/5 7/D/7 7/1'/1 7/G/2 7/G/3 7/G/8

7/G/ll 7/G/lS 7/G/14 7/G/15 8/.\/2 8/C/2

8/C/:l 9/B/I

SUMMARY OF SILT FACTORSt-(Conlinued)

I I I Silt

collecting 11,1ean area in H)60-GI annual

1Ni.!er s].1ni/cs Factors Factor --' --_ .... _. __ .. _, ._._--'-- --'-'-- ---. -----._- ---- --- -----~- - -----

Limpasa · . · . I lOG 0.17 , 0.17 Luwe"va · . 900 0.24 0.16 SOll tb" H.ukuru · . 362 0.08 O.ll L'J!lyangwa · . · . 190 1.40 1.43 Kasitu · . · . · . 283 1.34 1.99 Lunyangv.'a 10 0.05 0.08 Kasitu · . 804 1.07 1.70 H.unyina · . 346 O.ll 0'13 North Rumpi 117 0.10 O.ll I\{uhuju · . 29 O.HJ 0.24 Lura · . · . - Station

closed 0.06 Kambwiya · . 43 0.11 0.05 Lnviri · . · . · . 20 0.09 0.20 Sou th H.ukuru · . 4,577 0.35 0.38 Kaziwiziwi · . · . 61 0.13 0.09 North Rukuru · . 753 1.08 1.21 \Vovwe ..

Chitimoa Songwe

· . 134 Station closed 0.72

· . · . 11 0.60 0.50 · . · . 1,567 0.36 0.25

*Maximum figure since records commenced.

Total annual silt load in tons j"Silt factor=--

Total annual flow in acre~feet

36

I Estimated . maximU1'n

Pe-riod daily of record loai in in years tons* ----- --------

7 8,000 7 50,000 5 1,000 7 18,000 6 62,000 6 100 5 60,000 7 2,800 7 2,300 6 700

5 290 6 260 4 280 3 10,000 4 1,000 6 90,000

6 5,000 3 4,000 7 21,000

: 0 8 - ""'.,~ : 8 0 ... -

...-\S) ....

~~ & -

t:~ l&a4( va w ,. ~~ ·0 u..

~ '% ~ Q. n :1 w (!) z il ~ n

Q ,. ,.. • :E ~ ... ....l Q - Z .t. "" 0 • ~ -J. ... • I-:t .. .0

tl. w

WI > U. -tl. z ~ ~ -:z. ~

~ -0. IS:. -• th

~ ~ 0

I InUI1~

f 0 0 -2 -

! ~ 9 0 -- m:l!rJ;J

: -I-~ ~o ~ ~

$: I~ ~ ~ .... IBA

• ~ I!>' ~~ 2

~ I~ ~ if ~

q!)

3

iu'" I~~ I~~

-£.

(I]il .~ ~ ~ ~ - !Q~

~ ~~ I:: ~

w ;;...

- I~ ;1 0

.. fiI:" o~ fJ

WU) DQ -

ff §~ " -~ ~ ~ 2 -~ :H~I\;

.

-

_. -.. -.---gr~------~~~---------r-----_ .. ~_I

f-.

__ -trH-I-i-L"1 1"--~-

1++

" _. .... --

.-.-.~

--§ g g 9 -~§m

9 -5!

-I- ~ U

, 0

* I- -0- Il. w It) ~

U!I 'r

\!)

~ ~

~ % Q..

~ ~ ¥")

~ .... a :z ~ ¥") Q

'>->- ::r < ~ -Ni -

W ..JI ~ ~ 6 0- 0..

.0(

~ )

~

~ .. """" ~

:;:)

~ lilt ~ W

I&.

X :z .... ~ ~ 0

~ 'h

V "'t w -Q ~

th >- ~ I 0

I Z

Q 0 Q 0 - fJUIl' Q 0 2: -~ ~