table b1.3-6 stratigraphic classification of honiara city area · 2006. 11. 1. · (b-20) table...

The Study for Rehabilitation and Improvement of Solomon Islands Water Authority’s Water Supply and Sewerage Systems

Final Report : Main Report (Part B) (B-15)

B1.3.3 Groundwater Survey

(1) Geology

Rock formation in Honiara consists of limestone, calcareous sandstone/mudstone of Miocene to the recent, which overlies the basement rock, diorite of Oligocene. Stratigraphic classification of Honiara area is shown in Table B1.3-6.

Table B1.3-6 Stratigraphic Classification of Honiara City Area

Age Formation Rock facies Thickness of formation Distribution in Honiara City

Holocene Alluvium Sand, clay, gravel <30m Distributed in the coastal plain and bottom of valleys

Pleistocene Honiara Coral Reef Limestone Coral Limestone <60m Distributed upper half of Marine

terrace

Qua

tern

ary

Pliocene~Pleistocene Honiara Beds

Calcareous sandstone, mudstone, conglomerate,

limestone

<200m

Outcropping in the foot of marine terrace and can be encountered shallower than 200m from the ground surface.

Former~middle Miocene Mbonehe

Limestone Limestone <100m Not outcropping in Honiara City and encountered deeper than 100m from the ground surface.

Terti

ary

Late Oligocene Poha Diorite Fine Diorite -

Not outcropping in Honiara City and encountered deeper than 200m from the ground surface.

Source : Geology of the Honiara, MNR, 1979 Main faults in the study area extend the north-south direction and the west - east direction. Ngossi Fault and White River Fault with their branches represent faults of the north-south direction. There are many small faults extending from the west to the east parallel with the coastal line. In Mount Austin area, many faults were formed when the mountain was lifted up.

Final Report : Main Report (PART B) (B-16)


So

urce

: Geo

logy

of t

he H

onia

ra, M

NR

, 197

9

Figu

re B

1.3-

6 G

eolo

gica

l Map

of H

onia

ra C

ity A

rea

Age

Fo

rmat

ion

Sym

bol

Allu

vium

Q

a

Hol

ocen

e C

oral

reef

Q

r

Plei

stoc

ene

Hon

iara

Cor

al R

eef L

imes

tone

Qpr

Quaternary

Kom

bito

Mar

lQ

pk

Hon

iara

Bed

sQ

plh

Plio

cene

~Ple

isto

cene

Lu

ngga

Bed

sM

atan

iko

Silts

tone

Tp

-Qpl

m

Form

er~m

iddl

e M

ioce

ne

Mbo

nehe

Lim

esto

ne

Tmh

Tertiary

Late

Olig

ocen

e

Poha

Dio

rite

δ1



(2) Hydrogeology

(a) Aquifer classification

Aquifer of Honiara ground water basin is summarized as shown in Table B1.3-7.

Table B1.3-7 Aquifer in Honiara Groundwater Basin Formation Groundwater Merit and demerit in groundwater development

Alluvium Sand and gravel layer store the groundwater.

Area of aquifer distribution, size of aquifer and recharge area are too small. It is subject to sea water intrusion.

Honiara Coral reef limestone

Limestone has much porosity suitable for groundwater storage. The Groundwater occurs as perched water.

Limestone is distributed only in upper half of terrace, and size of this aquifer is small. Recharge area is also small. So this aquifer is not suitable for large groundwater development. In addition, there is a risk of groundwater contamination from town area.

Honiara Beds

This formation comprises sandstone and limestone forming good aquifer. Water from Kombito Spring and Panatina Borefield comes from this formation.

Sandstone and limestone form confined aquifer in the depth of less than 100m. All the boreholes that were drilled so far are taking groundwater from Honiara Beds.

Mbonehe Limestone

This formation keeps huge amount of groundwater within in cave system, which has large recharge area. White River spring originates from this formation.

This aquifer exists deeper than GL-100m over the study area. Limestone is compact with poor porosity. Cave system with the groundwater is locally developed. It is not easy to detect the groundwater of this aquifer because of deep occurrence of groundwater. This aquifer can not be direct target of groundwater development

Poha Diorite Groundwater occurs as fissure water.

This formation exists too deep in the ground for the study to be target for groundwater development.

Source : SIWA, MNR, JICA (b) Hydrogeology of Honiara Groundwater Basin

Hydrogeological structure of the Honiara can be simplified as shown in Figure B1.3-7. Aquifers in Honiara can be considered independent from the other groundwater basins. Lungga River becomes physical boundary of the groundwater basin in the western and the southern side. Iron Bottom Sound is the northern boundary of the groundwater basin. There is no physical boundary in western side. This report defines the groundwater basin that covers Honiara as “Honiara Groundwater Basin”. The groundwater in the basin flows from SSW to NNE direction to reach Iron Bottom Sound. This can be assumed based on the fact that both slope of hills and dipping of stratum face the same direction toward NNE. Honiara groundwater basin shows rectangle shape in plain, and aquifer is equally distributed all over the basin.



Source : JICA Study Team

Figure B1.3-7 Hydrogeological Structure of Honiara Groundwater Basin (c) Recharge to Honiara Groundwater Basin

Honiara Beds is distributed in the south of Honiara, where the aquifer is recharged by rainfall and rivers. Mbonehe limestone, which underlies Honiara Beds, has huge area of distribution in the south and the west of the basin, storing confined groundwater in its body. It is assumed that this confined aquifer provides groundwater upward to overlaying Honiara beds through fracture zones. In addition to this, down-ward groundwater recharge from Honiara Reef Limestone to Honiara Beds is also expected through fracture zones. Honiara Beds has good condition to get groundwater recharge.

(3) Electric Resistivity Prospecting

(a) Outline of survey

Electric resistivity survey was carried out in Honiara. There are 20 measuring points within Honiara Town Area as shown in Figure B1.3-8. Additionally, the figure shows measuring points that were carried out in the previous JICA Basic Design for the Project for Improvement of Water Supply System in Honiara Solomon Islands, 1996”.

Outline of the electric resistivity survey of the Study is shown in Table B1.3-8.

Area for groundwater recharge

Groundwater recharge from Lungg River

White River Spring Honiara Reef Limestone

Honiara City Alluvium

Poha Diorite

Mbonehe Limestones

Sea water intrusion

Faults

Faults Up-ward groundwater movement along faults

Honiara Beds (promising for groundwater development)

Honiara Groudwater Basin



Leg

end M

easu

ring

Poi

nts

of T

his

Stud

y

Mea

suri

ng P

oint

s of

The

Pre

viou

s JI

CA

Stu

dy

N

01

2km

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

11

01

00

10

00

AB

/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

<V

ES>

1101001000

110

100

100

0A

B/2

(m)

ρa(Ωm)

＜S-

1＞

＜S-

2＞

＜S-

9＞

＜S-

8＞

＜S-

5＞

＜S-

6＞

＜S-

7＞

＜S-

4＞

＜S-

3＞＜

S-20

＞＜S-

10＞

＜S-

11＞

＜S-

12＞

＜S-

14＞

＜S-

15＞

＜S-

13＞

＜S-

18＞

＜S-

19＞

＜S-

17＞

＜S-

16＞

So

urce

: JI

CA

Stu

dy T

eam

Figu

re B

1.3-

8 L

ocat

ion

of G

eoph

ysic

al P

rosp

ectin

g in

Hon

iara



Table B1.3-8 Electric Resistivity Prospecting

Method Configuration of electrode

Distance of current electrode (AB/2,m)

Depth for detection

No. of points

Instrument for prospecting

Electric resistivity prospecting

Schlumberger array

3, 5, 7, 10, 14, 19, 27, 37, 52, 72, 85, 105, 125, 160, 200, 250

Up-to around GL-100m 20

MiniSting R1 IP (Canada AGI company)

Source : JICA Study Team (b) Existing Resistivity Prospecting

Before interpretation of results of resistivity prospecting of the Study, results of actual drilling and result of resistivity prospecting was compared to examine accuracy of resistivity method. Result of the comparison is shown in Table B1.3-9. From the existing prospecting results, resistivity structure of aquifer has been interpreted as two to five layer-models in the Study Area, and it is concluded that resistivity method has enough accuracy to detect distribution of aquifer. Resistivity structure of aquifer is summarized as below.

• Resistivity of the first layer, the top layer under the ground-surface, is different from place to place. Thickness of the first layer is less than 10m, and this layer will not become aquifer regardless of its resistivity.

• The intermediate layer usually shows low to medium resistivity. It means that the intermediate layer consists of clayey material with low permeability. This layer causes the underlying layer to be confined.

• The lowest layer, which shows medium to high resistivity, is expected as aquifer. Layers with resistivity of less than 100Ωm are expected good aquifer comprising sand/sandstone/limestone. On the other hand, layers with resistivity more than 200Ωm may be Mbonehe Limestone, which is not good aquifer.

• It is assumed that sea water intrusion into aquifer occur, if the lowest layer shows resistivity of less than 2Ωm, in the area within 500m from the shoreline.



Site

Bore No.

Depth (GL-m) Rock Type Aquife

r or not

Electric logging (Ωm)

Analyzed structure

Type of apparent

resistively curve1)

Measurement points2)

0-24 Limestone ≑ 100 K-1

24-80 Sandstone 100-250

2-layers structure with 10 to 100Ωm

A-type curve with 10 to 100Ωm

ES-10/ES-11 of JICA BD Study

15-33 Sand 20-20033-51 Sand/Gravel 140-240K

ombi

to

K-2 51-80 Sand 40-160

3-layers structure with 10 to 100Ωm.

A-type curve with 10 to 40Ωm

ES-12/ES-13/ES-14/ES-15 of JICA BD Study

16-36 Sandstone 100-250

36-59 Sandstone/lime-stone/gravel 100-320W-2

59-80 Sandstone/lime -stone/gravel 100-260

3-layers structure with 12Ωm to 80Ωm.

H-type curve 10 to 40Ωm

ES-24 of JICA BD Study

24-45 Coarse sandstone 40-340

45-69 Medium sandstone/Silt- stone

40-100Whi

te R

iver

W-3

69-80 Medium to coase Sandstone

60-280

≑ 15Ωm A-type curve with 10 to 25Ωm

ES-25 of JICA BD Study

17-25 Sand and gravel/Silt ≑ 180 ≑ 9Ωm

25-69 Sand and gravel/Silt 20-80 ≑ 65Ωm

Mat

anik

o

M-2

69-100 Fine limestone × ≑ 180 ≑ 500Ωm

H-type curve with 10 to 500Ωm

S-20 of this Study

Note: 1. If layer structure is interpreted by three-layers structure with 1st-layer(ρ1), 2nd- layer(ρ2),3rd-layer(ρ3), it is defined as: H-type(ρ1>ρ2<ρ3 ), A-type(ρ1<ρ2<ρ3 ), Q-type(ρ1<ρ2>ρ3 ), K-type(ρ1>ρ2>ρ3 ).

2. JICA BD Study means “Basic Design for the Project for Improvement of water Supply System in Honiara Solomon Islands, 1996”.

Source : JICA Study Team (c) Result of Resistivity Prospecting

Results of electric resistivity prospecting of the Study is shown in Figure B1.3-8 and summarized in Figure B1.3-9. Result of the survey is summarizes as below.

• Electric resistivity structure of Honiara groundwater basin has homogeneous structure covering the entire city.

• There are excellent aquifers in the entire city between 20m to 100m in depth depending on place as shown in Figure B1.3-9.

• Capacity of aquifer seems high as indicated by the existing boreholes of SIWA.

• Drilling boreholes within Honiara town area will be highly successful.

Table B1.3-9 Comparison between Drilling Results and Resistivity Prospecting Results



<S-10>

1100

1 10 100 1000

AB/2(m)ρa(

Ωm

)

ρa(Ωm) : Apparent resistivity

AB/2 : Distance of electric electrode= depth of detection

Site Representative apparent resistivity curve No. Depth of aquifer(GL-m)S-1 20-100 S-2 10-100 S-3 20-100 S-4 20-100

White River ~ Rove Creek

<S-3>

110

100

1000

1 10 100 1000

AB/2(m)ρ

a(Ω

m)

Note) Depth of borehole is recommended less than100m. So screen should be installed between 20m and 100m in depth. Aquifer shallower than GL-20 is vulnerable to groundwater contamination.

No. Depth of aquifer (GL-m)

S-5 20-100 S-6 20-100 S-7 40-100 S-8 50-100 Rove Creek ~ Mataniko

River

<S-7>

110

100

1000

1 10 100 1000

AB/2(m)

ρa(

Ωm

)

Note) The same as above.

No. Depth of aquifer(GL-m)S-9 20-60

S-10 30-100 S-11 80-100 S-12 30-100 S-13 20-100 Mataniko River ~ Vara

creek

<S-10>

1

10

100

1000

1 10 100 1000

AB/2(m)

ρa(

Ωm

)


No. Depth of aquifer(GL-m)S-14 60-100 S-15 20-100 S-16 20-100 S-17 40-100 S-18 30-100 S-19 20-100 S-20 40-70

Vura Creek ~ Kombito Site

<S-18>

1

10

100

1000

1 10 100 1000

AB/2(m)

ρa(

Ωm

)


Legend


Figure B1.3-9 Summary of Electric Resistivity Prospecting

Layer model (blue line) Observed apparent resistivity (black circle)

Theoretical apparent resistivity of layer model (red curve)



(d) Sea Water Intrusion

Sea water intrusion into aquifer is likely to occur in the coastal region. Electric resistivity prospecting is useful to judge whether sea water intrusion is taking place or not. Sea water intrusion into aquifer was observed in the coastal area of Honiara city by the previous JICA Study for basic design for the Project for Improvement of water Supply System in Honiara Solomon Islands, 1996. According to this result, aquifer that is intruded by sea water can be detected as layer with resistivity of lower than 2Ωm.

Table B1.3-10 Sea Water Intrusion in the Existing Study

Area Length of sea water intrusion from the coast line Aquifer of intrusion

Panatina Less than 300m Alluvium Sand deposit Ndondo Creek Less than 400m Alluvium Sandsand deposit Source : JICA

Electric resistivity prospecting was carried out in the area of Honiara beds in this Study. According to its results, it becomes clear that seawater intrusion is not taking place in aquifer that is located farther than 300m to 500m from the shoreline. Seawater intrusion may be taking place only in alluvial sand-layer that is distributed in the coastal plain, and sea water does not reach underlying Honiara Beds in the shoreline.

(4) Analysis of Sea Water Intrusion

(a) Example of Panatina Bore Field

There are three boreholes in Panatina bore fields of the eastern coastal area of Honiara City. The boreholes are located in 150m distance with each other. Total yield of boreholes is 3,800m3/day with dynamic groundwater level of 32m below surface, which is 20m below the sea level. Distance from the coastal line to bore field is 570m. According to Ghyben-Herzberg’s law, seawater will easily intrude into borehole if groundwater level is lowered below the sea level. However, sea water intrusion into boreholes has not yet taken place in Panatina bore field even though groundwater level was kept lower than the sea level for more than 15 years.

(1) (2)


Figure B1.3-10 Hydrogeological Situation of Panatina Bore Field Situation of sea water intrusion is considered that shown in Figure B1.3-10(2) not Figure B1.3-10(1). Sea water intrusion into Honiara Beds has not yet taken place in the inland area where Panatina bore field is located. Results of electric resistivity prospecting by JICA in 1996 supported this situation.

Situation of sea water intrusion is considered as shown in Figure B1.3-11. This situation can be true not only in Panatina Area but also in many places in Honiara City. Whether sea water will intrude into borehole or not by new groundwater development depends on factors such as i) yield from borehole, ii) amount of natural groundwater flow, iii) distance between bore and the shoreline and iv)

Panatina Tank

Panatina Well

Upconing of Interface

Panatina Tank

Panatina Well

Toe of Sea Water Intrusion

Fresh Water

Sea Water

Sea Water



permeability of aquifer. Possibility of sea water intrusion by pumping-up from boreholes near the sea can be analyzed by formulas listed in Table B1.3-11. This table also shows result of analysis of Panatina borefields.


Figure B1.3-11 Situation of Sea Water Intrusion

Table B1.3-11 Analysis of Sea Water Intrusion in Honiara Groundwater Basin Items Method for analysis and result

Groundwater flow in Honiara Groundwater Basin

According to water balance analysis, groundwater flow from Honiara groundwater basin into the sea is estimated 68,513m3/day. Total length of coastal line in the basin is 10km. So unit groundwater flow of 1 m width is 68,513m3/day/10,000m = 6.8 m3/day/m.

Length of sea water intrusion in Honiara Groundwater Basin

Length of sea water intrusion in Honiara Groundwater basin is calculated by formula below.

Qo× L=KεB2/2 L：length of intrusion(m), Qo：Unit groundwater flow per 1m width(m3/day/m) K：Coefficient of permeability(m/day), ε：1/40, B：Thickness of aquifer(m)

So the current length of sea water intrusion is calculated as follows. L=KεB2/(2×Qo)=0.4×(1/40)×2002/(2×6.8)=29m

Possibility of sea water intrusion into boreholes in Panatina bore field

Condition to prevent sea water intrusion is as follows (see Figure-B1.1-8).

Stagnant point (XM) > toe of sea water intrusion (Xs) Where, • XM=a｛1-Q/(π・a・Qo)｝1/2 • Xs satisfies relationship of KεB2/2=Q/ (2π)In((Xs-a)2/(Xs+a)2)1/2.

K：Coefficient of permeability(m/day), ε：1/40, B：Thickness of aquifer(m) a：Distance between shoreline and bore(m), Q：Yield(m3/day) Qo：Unit groundwater flow per 1m width(m3/day) In case of Panatina Bore Field, Qo =6.8 m3/day, Q =3,800 m3/day, XM=473m, Xs=43m. So it is concluded that XM>Xs. Then, possibility of sea water intrusion is low as long as the current yield is kept in the future.


B1.3.4 Water Quality

Water quality survey in Honiara consists of field water quality survey at site and water quality analysis in the laboratory. Field water quality survey was conducted by the Study Team with cooperation of SIWA. Water quality analysis was conducted by SIWA laboratory.

Field water quality survey was conducted in June, August, November and December 2005 and water quality analysis was conducted from June to July 2005 for an investigation of surface water and

Q

Qo H

yy

Xs

φh

B

Confined Aguifer

Fresh Water

XM a



ground water quality in the dry season and rainy season.

The measurement points of field water quality are shown in Figure B1.3-12 and the results are shown in Table B1.3-12. The water sampling points for water quality analysis in the laboratory is shown in Table B1.3-13 and the results are shown in Figure B 1.3-13.

DO and COD survey results are shown in the figures from B1.3-14 to B1.3-20 for the measuring points in each river. DO and COD value are important items for evaluating the contamination of river water and seawater.



Tabl

e B

1.3-

12

Res

ults

of F

ield

Wat

er Q

ualit

y Su

rvey

W

TEC

Turb

idity

pH

Do

CO

DW

TEC

Turb

idity

pH

Do

CO

DW

TEC

Turb

idity

pH

Do

CO

DW

TEC

Turb

idity

pH

Do

CO

DH

oniy

ara

m

s/m

mg/

lm

g/l

mg/

l

ms/

mm

g/l

mg/

lm

g/l

m

s/m

mg/

lm

g/l

mg/

l

ms/

mm

g/l

mg/

lm

g/l

white r

iver

1 K

ongu

lai sp

ring

23.9

34.6

47.8

7.2

31

23.9

34.9

15

7.7

97.6

11

24.9

32.8

77.8

5.7

26

24

22.7

92

7.3

6.0

46

Kovi

sin

khole

--

--

--

--

--

--

23.6

25

68.6

7.4

36

--

--

--

white r

iver

2 d

ow

n s

tream

124.1

26

17.6

7.9

21

24

33.6

17

7.6

67.9

61

25

30.1

38.1

6.4

35

25.7

21.4

48

7.8

7.0

57

white r

iver

3 d

ow

n s

tream

225.9

32.7

28.2

7.8

52

25

35.1

516

8.2

77.3

729.8

24.6

78.1

7.9

827.7

25.7

11

86.4

17

white r

iver

4 d

ow

n s

tream

326.1

36.1

27.9

6.5

94

25.8

37.4

18

7.9

66.3

58

30.2

34.2

57.6

4.5

47

28.1

33.1

07.3

4.5

27

white r

iver

5 d

ow

n s

tream

426.5

35.8

57.7

4.8

26

26.2

38.8

26

7.6

33.8

630.2

28.9

17.4

0.7

58

28.6

36

17.3

2.8

7w

hite r

iver

6 d

ow

n s

tream

527.6

38.3

57.6

3.5

49

26.5

38

28

7.5

63.3

19

27.7

39.1

47.3

1.4

828.6

35.7

27.3

2.5

67

white 7

riv

er

mouth

26.8

37.3

57.5

2.3

55

26.6

39

24

7.5

22.2

69

28

28.4

07.4

0.9

49

26.7

39.1

27.3

1.9

99

white 8

riv

er

sea

28

-4

7.9

6.2

81

27.8

-27

7.9

6.0

11

29.9

-5

7.5

6.6

229.1

-0

7.7

52

white r

iver

9 w

ell-

126.4

46.1

14

7.6

0.8

1-

--

--

--

26.3

41.6

57.3

2.4

626.4

26.9

76.7

2.5

47

white r

iver

10 w

ell-

226.1

42.1

14

7.5

1.3

1-

--

--

--

26.3

49.6

87.5

3.4

25

26.1

48.4

77.3

2.6

17

white r

iver

11 w

ell-

325.4

36.1

10

8.1

1.7

8-

--

--

--

No w

ater

flow

No o

verf

low

white r

iver

12 w

ell-

427.1

56.1

15

7.4

1.0

8-

--

--

--

27.2

48.6

77.1

2.1

66

27

52.1

87.2

1.8

17

Rove

cre

ek1

Spring

Wat

er

26.2

56.1

2.2

37.6

2.2

3-

26.2

48.3

14

6.8

25.6

11

27

48.5

77.6

4.7

16

27.1

31.8

56.8

5.0

46

Rove

cre

ek

Dow

nst

ream

of sp

ring

wat

er

26.2

49

15

77.6

126.1

50.4

15

7.1

25.4

31

26.2

42.1

87.4

5.0

65

26.9

44.3

66.8

4.8

56

Rove

cre

ek

3 R

iver

Cro

ssin

g W

eir

26.9

51

10

7.3

5.7

126.2

47.8

16

7.0

65.3

127.6

47.1

67.3

4.6

37

28.8

47

35

7.2

7.0

27

Rove

cre

ek

4 S

IWA

wat

er

reso

urc

es

spill

way

--

--

--

26.7

54.6

16

7.2

26.2

1N

o w

ater

flow

26.7

49.4

76.9

3.2

46

Rove

cre

ek5

Riv

er

(Bota

nic

al g

arde

n)

26.8

35

14

7.6

6.7

61

26.4

52.6

15

7.7

46.9

41

27.6

49

67.7

5.3

46

27.8

50.9

77.5

5.3

56

Rove

cre

ek

6 R

ove

cre

ek

mouth

26.8

35

7.9

5.2

226.3

49.6

17

7.9

96.6

96

29.2

52.5

37.9

5.7

99

26.2

48

47.6

3.0

57

Rove

cre

ek

7 R

ove

cre

ek

5 s

ea

27.1

-14

8.1

40

28.1

-16

7.9

17.3

50

31

-6

7.8

8.7

131.2

-2

88.2

52

Mat

anik

o r

iver

1 dow

n s

tream

125.8

29.6

38.2

7.9

81

25.1

39.3

88.2

55.3

29

27.4

20.5

48.1

7.7

58

26.1

23.2

58.2

7.9

6M

atan

iko r

iver

2 dow

n s

tream

226.4

41

37.8

6.6

54

25.8

37.2

15

7.9

44.6

36

26.6

28.7

38

5.4

726

38

37.6

4.9

15

Mat

anik

o r

iver

3 dow

n s

tream

326.4

48

26

7.8

4.9

55

26.7

44.1

20

7.7

94.2

37

32.3

34.5

47.8

3.1

58

26.6

40.9

10

7.4

3.8

97

Mat

anik

o r

iver

4 m

outh

26.6

45

75

7.8

3.9

35

25.7

237.7

18

7.6

13.3

85

26.1

990

58.1

3.3

37

25.1

-4

7.6

4.3

16

Mat

anik

o r

iver

5 s

ea

28

102

7.1

8.6

52

29.4

-21

8.0

23.8

30

31.1

-0

7.8

6.6

67

30.3

-28

86.3

75

Mat

anik

o r

iver

6 t

uva

ruvu

outf

all ups

trre

am25.4

40.1

12

8.2

2.3

2-

--

--

--

28.5

25.3

08

7.3

725.9

31.3

38

7.1

97

Mat

anik

o r

iver

7Tuva

ruvu

outf

all dow

nst

ream

25.3

40.1

98.3

2.2

5-

--

--

--

28.9

50.5

17.6

4.3

49

26.2

32.9

77.7

650+

Mat

anik

o r

iver

8V

asa

cre

ek

outf

all upst

ream

26.9

68.1

44

8.1

2-

--

--

--

29.1

54.5

17.9

5.0

98

26.1

34.9

07.9

4.9

17

Mat

anik

o r

iver

9 V

asa

cre

ek

outf

all do

wnst

rea

25.6

58.1

77.8

1.8

3-

--

--

--

29.1

49.8

10

7.6

2.9

59

26.8

44

07.6

4.7

750+

Kom

bito

cre

ek

1 s

prin

g25.2

39.4

18

7.4

7.4

16

25.2

47.9

12

7.5

4.0

81

25.2

32.5

23

7.9

5.3

27

25.3

42

77.3

5.3

36

Kom

bito

cre

ek

2 s

prin

g226.3

49.6

20

7.1

5.2

96

26

48.2

17

7.0

63.0

95

26.4

36.2

27

5.3

28

26.3

41.6

76.9

5.3

66

Kom

bito

cre

ek

3 d

ow

n s

tream

126.8

35.1

39

7.2

0.6

78

27.1

48.4

20

7.1

81.6

57

27.7

44.8

37

7.7

2.3

47

28

44.3

12

7.1

0.2

99

Kom

bito

cre

ek

4 d

ow

n s

tream

226.1

48

44

8.1

7.0

98

27.3

36.1

34

8.1

22.9

98

27

42

88.3

6.3

57

28.6

43.9

16

7.9

5.7

39

Kom

bito

cre

ek

5 s

prin

g 3

27.5

62.8

21

7.1

5.2

24

27.3

63.8

19

7.1

12.8

35

27.3

57.4

12

7.6

3.9

47

27.5

56.3

06.9

3.7

36

Kom

bito c

reek

6 S

IWA

well-

126.8

68.1

14

7.2

1.3

6-

--

--

--

No o

verf

low

No o

verf

low

Kom

bito c

reek

7 S

IWA

well-

226.7

50.1

14

7.4

2.0

4-

--

--

--

No o

verf

low

No o

verf

low

Kom

bito c

reek

8 E

uw

ell

26.1

46.1

07.6

1.9

5-

--

--

--

26.4

45.4

77.5

3.7

57

26.1

44.9

77

3.2

84

Kom

bito

cre

ek

9 M

t.A

ust

in n

ew

spr

ing

26.7

40.1

13

7.4

1.0

5-

26.1

45.1

11

7.1

87.1

-26.1

39.2

87.7

5.4

47

-Kom

bito

cre

ek

10 M

amule

le s

prin

g25.9

48.1

15

7.3

1.6

9-

25.9

44.6

14

7.0

97.2

5-

25.9

44.2

76.4

4.6

36

26

44.5

76.9

4.2

6Tan

ahue 1

mouth

26.6

66.1

87.7

0.6

4-

27.1

72.2

20

7.6

93.7

47

26.6

53.8

43

8.1

4.0

99

30.7

68

17.3

1.1

89

Tan

ahue 2

sea

29.2

14

7.9

0.9

9-

28.2

-18

8.0

76.8

50

28.5

-37

7.9

4.4

11

30.9

-7

7.9

6.1

32

Lungg

a rive

r 1

28.7

29.8

18

8.1

8.2

46

26.7

23.3

16

8.2

18

627.6

15

27.8

7.0

87

--

--

--

Lungg

a rive

r 2

26.6

25.7

17

8.2

8.2

36

27

20

17

8.0

28.1

26

27.5

16.2

27.8

6.5

68

--

--

--

Outf

all-

1 R

ove

cre

ek

sew

era

ge o

ut

flow

30.8

-21

7.8

6.4

030.4

-2

7.9

5.6

32

Outf

all-

2 P

oin

t C

ruis

e O

utf

all

30

-27

7.9

2.5

42

30.5

-5

7.7

6.0

91

Outf

all-

3 S

t.N

ichola

s O

utf

all

31.1

-1

8.1

8.2

72

31.7

-5

7.9

7.4

5O

utf

all-

4 B

ahai

Sew

arag

e O

utf

all

28

-44

8.0

13.1

12

30.1

-2

85.0

65

30.5

-4

7.9

4.9

71

Outf

all-

5 K

uku

m S

ew

era

ge O

utf

all

28.6

-23

8.0

36.6

50

30.9

-6

83.6

32

31

-6

7.8

3.6

21

Outf

all-

6 K

uku

m M

buaV

alle

y O

utf

all 1

30.6

-7

8.1

7.4

92

31.4

-7

86.5

61

Outf

all-

7 K

uku

m M

buaV

alle

y O

utf

all 2

31.8

-13

8.2

7.7

52

31.8

-0

7.9

6.1

91

Outf

all-

8 N

aha

Outf

all

30.8

-6

8.2

6.9

92

31.4

-7

87.0

21

Outf

all-

9 V

ura

Outf

all

30.4

-4

8.1

4.7

32

30.9

-5

7.9

4.5

91

Outf

all-

10 R

anad

i O

utf

all

30.8

-5

8.3

7.2

21

31.4

-5

7.9

6.0

92

Outf

all-

11 K

G V

I O

utf

all

30.7

-35

7.8

0.2

97

31.8

-93

7.6

4.4

32

2005.6

2005.8

2005.1

12005.1

2

So

urce

: JI

CA

Stu

dy T

eam



Whi

te R

iver

1 3 9

10

4

5

6

7 8 12

11

Rov

e C

reek

1 2

2

3

4 5

Mat

anik

o R

iver

1672

89

45

3

10Tana

hue

2 1

1 2

3

57

6 8

9

Kom

bito

Cre

ek

1

2

Lun

gga

Riv

er

Lege

nd

Surv

ey p

oint

at s

prin

g, ri

ver a

nd s

ea

Surv

ey p

oint

at b

oreh

ole

Surv

ey p

oint

at O

utfa

ll

①

･･･⑩

：Su

rvey

poi

nt n

umbe

r

(Ref

er

to T

able

-B1.

3-12

)

Sand

Min

ing

N

0

1

2km

1

2

34

5

6

7 8

9

10

11

So

urce

: JI

CA

Stu

dy T

eam

Figu

re B

1.3-

12

Mea

sure

men

t Poi

nts o

f Fie

ld W

ater

Qua

lity



Tabl

e B

1.3-

13

Res

ults

of W

ater

Qua

lity

Ana

lysi

s So

urce

Tap

Nitr

ate

Nitr

iteN

itoro

gen-

amm

onia

Mn

FeK

Tota

l har

dnes

sSO

4Zn

Cl2

Cl

FC

aM

gC

uPb

PC

r (V

I)I

Al

Benz

otria

zole

Phen

olTo

tal C

olifo

rmW

HO

Gui

delin

e50

3-

0.4

--

--

--

51.

5-

-2

0.01

-0.

05-

--

-H

ON

IAR

A W

EL

L・

SPR

ING

Whi

te ri

ver B

ore-

1

0.02

0.00

20

00.

072

071

5.32

0.06

10

0.04

733

360.

020

0.00

90.

021

00.

0084

00

>200

Whi

te ri

ver B

ore-

2

0.03

0.00

210

00.

071

0.13

117

7.32

0.06

50

0.01

10.

014

7743

0.03

00.

019

0.02

40

0.00

790

00

Whi

te ri

ver B

ore-

3

0.02

0.00

220

0.00

10.

070.

1297

6.44

0.06

60

0.03

50.

003

4739

0.02

00.

036

0.02

00.

008

00

4W

hite

rive

r Bor

e-4

0.

094

0.00

470

0.00

310.

028

0.00

5513

70.

064

0.00

380

0.04

30

6632

0.02

80

00.

038

00.

058

00

0M

atan

iko

Bore

M-2

0.

030.

010.

0151

0.54

0.00

32.

5120

5.5

0.01

30

00.

023

0.00

114

4.4

11.0

20.

022

00.

061

0.1

0.07

80

0>2

00M

atan

iko

Bore

l M-4

0.

030.

037

0.01

830.

540.

003

1.95

198

0.01

30.

017

00.

035

0.00

614

4.4

11.0

20.

022

00.

033

0.1

00.

078

00

>200

Mat

anik

o SI

WA

Bor

e-1

0.

031

0.01

020.

152

0.51

0.00

32.

5220

70.

009

00.

012

0.00

510

896

0.02

00.

047

0.03

10

0.00

790

00

Kom

bito

Bor

e K

-1

0.00

570

00

0.02

70

870.

034

0.06

50

0.06

10

47.9

230.

034

00

0.05

70

0.00

330

05

Kom

bito

Bor

e K

-2

0.04

40

00.

021

0.02

70

930.

016

0.04

90

0.05

50

44.3

36.6

0.04

30

00.

057

00.

017

00

17K

mbi

to E

U B

ore

Pa

natin

a Bo

re -1

0.

031

0.00

130

0.00

450.

119

0.00

517

30.

20.

0238

00.

026

0.00

373

.478

.11

0.02

20

0.00

40.

016

00.

009

00

Pana

tina

Bore

-2

0.04

0.00

540

0.00

320.

265

203

0.2

0.02

440

0.02

20.

009

54.1

78.3

40.

024

00

0.01

80

0.00

70

00

Pana

tina

Bore

-3

0.04

20.

0045

0.00

570.

0033

0.00

570.

012

201

0.2

0.02

430

0.01

176

.497

.70.

022

00.

012

0.01

80

0.00

70

00

Pana

tina

Tank

0.

051

0.00

170

0.00

350.

201

0.00

116

30.

040.

0251

00.

026

88.4

760.

023

00.

016

00.

009

00

Whi

te R

iver

Con

gula

i sp

ring

0.

170.

006

0.6

0.02

0.01

10.

1414

40.

30.

864

00.

001

0.00

576

.462

0.04

60

0.02

10.

0046

00

>200

Rov

e sp

ring

0.

90.

61.

030

0.43

0.33

740.

043

0.05

10

0.03

70.

027

3628

0.03

10

0.02

40

0.00

880

0>2

00K

ombi

to sp

ring-

1

1.07

0.04

60.

960.

041

0.01

10

660.

010.

033

0.04

20

37.7

290.

003

00

0.01

20

0.06

20

00

Kom

bito

sprin

g-2

1.

380.

096

0.04

40.

038

0.02

30.

027

710.

021

0.06

20

0.05

70

4338

.50.

091

00.

010.

047

00.

055

00

>200

Mt.A

uste

n ne

w sp

ring

sour

ce

0.93

0.04

60.

062

0.01

10.

019

0.03

864

0.00

50.

012

00.

003

0.00

241

370.

021

00.

003

0.03

30

0.09

10

0>2

00M

amul

ele

new

prin

g so

urce

1.

50.

009

0.00

53.

330.

011

0.24

50.

20.

863

05

014

.76.

080.

070

0.14

0.00

90.

140.

005

00

0H

ON

IAR

A T

AP

WA

TE

R

Whi

te ri

ver h

igh

leve

l sys

tem

0.

180.

006

0.01

10.

50.

039

0.09

157

0.1

0.21

0.3

0.81

0.01

757

.744

.70.

048

00.

510.

023

00.

084

00

0W

hite

rive

r spr

ing

grav

ity sy

stem

0.

180.

005

0.02

40.

530.

041

0.09

155

00.

310.

60.

790.

022

5641

0.54

00.

590.

023

00.

081

00

0R

ove

grav

ity sy

stem

0.

90.

61.

030

0.43

0.33

740.

043

0.05

10

0.03

70.

039

3628

0.03

10

0.02

40

0.00

880

0M

atan

iko

Skyl

ine

Syst

em

0.03

70.

0102

0.09

30.

044

0.07

51.

7720

30.

006

0.03

70.

40.

012

0.00

2297

860.

020

0.03

80.

031

0.07

60

00

Mat

anik

o SI

WA

Sys

tem

0.02

10.

002

0.06

20.

061

0.07

51.

0319

50.

003

0.04

50.

30.

017

0.00

2298

860.

021

00.

038

0.02

20

0.05

60

0K

ombi

to k

-1.k

-2 sy

stem

0.

040.

0093

0.00

80.

017

0.01

10.

007

214

5.37

0.86

40

6.3

010

7.4

6.06

0.04

30

0.00

10.

10.

030.

0087

00

78K

ombi

to sp

ring

syst

em

0.93

0.08

70.

063

0.03

80.

035

0.02

786

0.02

10.

062

0.3

0.05

70.

0143

350

0.01

0.04

20

0.05

50

0>2

00Pa

natin

a sy

stem

0.

051

0.00

170

0.00

350.

201

0.00

116

30.

004

0.25

10

0.02

688

.476

0.02

30

0.01

60.

009

00

0

Not

es:

Uni

t of t

he a

bove

is a

s fol

low

s;

- M

PN /

mL

for T

otal

Col

iform

Bac

teria

-

mg

/ L fo

r oth

er it

ems

Sour

ce :

WH

O's

Gui

delin

e va

lue

Sour

ce, G

uide

lines

for d

rinki

ng-w

ater

qua

lity,

3rd

editi

on(W

HO

200

4)

table b1.3-6 stratigraphic classification of honiara city area · 2006. 11. 1. · (b-20) table...

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