HY

DR

OL

OG

ICA

L P

RO

CE

DU

RE

HP

32

HP 32 HYDROLOGICAL PROCEDURE

HYDROLOGICAL STANDARD FOR RAINFALL STATION

INSTRUMENTATION

DEPARTMENT OF IRRIGATION AND DRAINAGE MALAYSIA

i

DISCLAIMER

The department or government shall have no liability or responsibility to the user or any other person

or entity with respect to any liability, loss or damage caused or alleged to be caused, directly or

indirectly, by the adaptation and use of the methods and recommendations of this publication,

including but not limited to, any interruption of service, loss of business or anticipatory profits or

consequential damages resulting from the use of this publication.

Opinions expressed in DID publications are those of the authors and do not necessarily reflect those

of DID.

Copyright ©2018 by Department of Irrigation and Drainage (DID) Malaysia Kuala Lumpur, Malaysia.

Perpustakaan Negara Malaysia Cataloguing-in-Publication Data

HYDROLOGICAL STANDARD FOR RAINFALL STATION INSTRUMENTATION. HP 32

(HYDROLOGICAL PROCEDURE ; HP 32)

ISBN 978-983-9304-38-1

1. Hydrological stations--Malaysia.

2. Hydrology--Malaysia.

3. Government publications--Malaysia.

I. Department of Irrigation and Drainage Malaysia.

II. Series.

551.5709595

All rights reserved. Text and maps in this publication are the copyright of the Department of Irrigation

and Drainage Malaysia unless otherwise stated and may not be reproduced without permission.

ii

PREFACE

The Hydrological Procedure (HP) No 32: Hydrological Standard for Rainfall Station Instrumentation

sets out guidelines and practices for the installation, operation and maintenance of rainfall

instrumentation in the field of hydrology, enabling them to carry out their work more efficiently. The

detailed description of the theoretical basis and applications of hydrological methods and techniques

are beyond the scope of this guide, although references to such documentation are provided

wherever applicable. It is hoped that this HP will be used, not only by Jabatan Pengairan dan Saliran

(JPS) Malaysia, but also by other stakeholders and agencies involved in water resource management

in general, and in water resource monitoring and assessment in particular.

Menara Teknik was commissioned by the Division of Water Resources and Hydrology to produce

Hydrological Procedure No 32: Hydrological Standard for Rainfall Station Instrumentation through

“Development of Hydrological Procedure No. 32: Hydrological Standard for Rainfall Station

Instrumentation, Hydrological Procedure No 33: Hydrological Standard for Water Level Station

Instrumentation and Hydrological Procedure No 35: Hydrological Standard for Water Quality Station

Instrumentation”, contract no. JPS/IP/C/H/06/2016. The HP 33: Hydrological Standard for Water Level

Station Instrumentation and HP 35: Hydrological Standard for Water Quality Station Instrumentation

were also produced under the same commission.

iii

ACKNOWLEDGEMENT

The authors greatly acknowledge the valuable contribution and feedback from Department of

Irrigation and Drainage (DID) personnel especially the Director of Water Resources Management and

Hydrology, Dato’ Ir. Haji Nor Hisham Bin Mohd. Ghazali, Director of National Flood Forecasting and

Warning Centre (PRABN), Pn. Hajah Paridah Anun Binti Tahir and the staff namely Ir. Rajaselvam a/l

Govindaraju, Ir. Hasanuddin Bin Mohd Ibrahim and En. Hairuy Azmi bin Aziz.

Table of Contents

DISCLAIMER.............................................................................................................................................. i

PREFACE .................................................................................................................................................. ii

ACKNOWLEDGEMENT ............................................................................................................................ iii

1. Introduction .................................................................................................................................... 1

2. Review of Existing Rainfall Gauges ................................................................................................. 1

Non Recording Rain gauge ...................................................................................................... 2

Recording Rain Gauge ............................................................................................................. 2

Tipping Bucket ................................................................................................................. 3

Weighing Gauge .............................................................................................................. 4

Radar ............................................................................................................................... 7

3. Procedure in Selecting Rainfall Gauges .......................................................................................... 9

4. Selection of Site .............................................................................................................................. 9

5. Instrumentation ............................................................................................................................ 10

General Specification of Tipping Bucket ............................................................................... 10

General Specification of Windshield ..................................................................................... 11

General Specification of Pole Stand ...................................................................................... 11

General Specification of Data Logger .................................................................................... 12

General Specification of Manual Rain Gauge ....................................................................... 12

6. Construction of Station ................................................................................................................. 13

Station ................................................................................................................................... 13

Enclosure ............................................................................................................................... 14

Earthing ................................................................................................................................. 14

TN-C System .................................................................................................................. 17

TN-S- System ................................................................................................................. 17

TN-C-S System ............................................................................................................... 18

T-T System ..................................................................................................................... 19

IT-System ....................................................................................................................... 19

Lightning Protection .............................................................................................................. 20

Conduit .................................................................................................................................. 22

Fencing .................................................................................................................................. 23

Type of Fencing ............................................................................................................. 23

Comparison of Type of Fencing..................................................................................... 25

Signboard .............................................................................................................................. 25

7. Installation of Instrument ............................................................................................................. 25

Installation of Tipping Bucket ............................................................................................... 25

Installation of Mini Data Logger ............................................................................................ 26

8. Solar Power Supply ....................................................................................................................... 26

9. Telemetry and Communication System ........................................................................................ 27

Remote Terminal Unit (RTU) ................................................................................................. 27

Communication Instruments ................................................................................................ 29

Radio Communication ................................................................................................... 29

GSM/ EDGE Communication – 3G/4G .......................................................................... 30

Satellite Communication ............................................................................................... 30

10. Maintenance of Instruments .................................................................................................... 31

11. Calibration of Instruments ........................................................................................................ 32

Calibration Procedure ........................................................................................................... 32

How and When to Calibrate .................................................................................................. 32

12. Guidelines for Safety & Health .................................................................................................. 33

Site Tidiness .......................................................................................................................... 33

Working at Height ................................................................................................................. 33

General Provisions ........................................................................................................ 33

Guard Rails .................................................................................................................... 34

Protective Equipment ........................................................................................................... 34

Safety Helmet ................................................................................................................ 34

Footwear ....................................................................................................................... 34

Working in Hot Environment ................................................................................................ 35

Electrical Hazard.................................................................................................................... 35

Safety Procedures in Handling Electrical Equipment .................................................... 35

13. Do’s and Don’ts ......................................................................................................................... 36

14. Summary Sheet ......................................................................................................................... 37

15. References ................................................................................................................................ 39

Appendix A: Related Documents from Ms ISO 9001: 2015 ............................................................ A1-A4

Appendix B: List of Drawing ............................................................................................................ B1-B9

List of Figures

Figure 1 Typical Tipping Bucket .............................................................................................................. 4

Figure 2 Typical Weighing Gauge ............................................................................................................ 5

Figure 3 How a Rainfall Radar Works (Met Office UK 2017)................................................................... 7

Figure 4 X-band MP radar at Funabashi, Japan 9 (MLIT 2013) ............................................................... 8

Figure 5 Tipping Bucket Installed at the Top of Station Housing .......................................................... 13

Figure 6 Illustration for Earthing and Protective Conductor System .................................................... 15

Figure 7 TN-C System ............................................................................................................................ 17

Figure 8 TN-S- System ........................................................................................................................... 18

Figure 9 TN-C-S System ......................................................................................................................... 18

Figure 10 TT-System .............................................................................................................................. 19

Figure 11 IT-System ............................................................................................................................... 19

Figure 12 Security Fence ....................................................................................................................... 23

Figure 13 Anti-Climb Fence ................................................................................................................... 24

Figure 14 Chain-link Fence .................................................................................................................... 24

List of Table

Table 1 General Specification of Weighing Type Tipping Bucket ........................................................... 6

Table 2 Comparison of Different Type of Fencing ................................................................................ 25

Table 3 Technical Specification of RTU ................................................................................................. 27

Table 4 Summary of Specification of VHF Band .................................................................................... 29

Table 5 Summary of Safety and Health Guidelines ............................................................................... 33

file:///F:/WORK/MTEKNIK_HP%20PROCEDURE/HP%2032%20BOOK/HYDROLOGICAL%20PROCEDURE%20NO%2032.docx%23_Toc510700859file:///F:/WORK/MTEKNIK_HP%20PROCEDURE/HP%2032%20BOOK/HYDROLOGICAL%20PROCEDURE%20NO%2032.docx%23_Toc510700861file:///F:/WORK/MTEKNIK_HP%20PROCEDURE/HP%2032%20BOOK/HYDROLOGICAL%20PROCEDURE%20NO%2032.docx%23_Toc510700862file:///F:/WORK/MTEKNIK_HP%20PROCEDURE/HP%2032%20BOOK/HYDROLOGICAL%20PROCEDURE%20NO%2032.docx%23_Toc510700863

1

1. Introduction

Since decades, Jabatan Pengairan Saliran (JPS) Malaysia has been the national hydrological agency

that develops hydrological stations nationwide to collect and obtain data for water resource

assessment, planning, development, early flood warning and river monitoring purposes. This

procedure is used as the standard instrumentation, installation and maintenance for rainfall stations

in Malaysia.

In fact, changes in instrumentation over the years have improved the time resolution and rainfall

depth over the recording history in many sites. Improvements in resolution however come at a cost

of maintaining stationarity. Also, the time interval pertaining to data collected has significantly

changed over time.

Over the last 60 years, rainfall intensity is recorded as a total over time interval. Often, the time

intervals are set hourly, 15 minutes, 7.5 minutes, 6 minutes or 5 minutes. However, the current data

loggers permit a greater range of options and a quick time resolution can now be achieved.

2. Review of Existing Rainfall Gauges

Rainfall is measured using rain gauge installed at a location of interest. Rainfall collected at this point

represents the rainfall volume of the area around the rain gauge. For more than 50 years, JPS has

been recording point rainfall data using rain gauge. There are two type of rainfall gauges;

i. Non-recording rain gauge; and

ii. Recording rain gauge.

Previously, rainfall data were manually collected or recorded by personnel who visit the rain gauge

stations regularly, to measure the rainfall accumulated since the previous visit. The rainfall that is

manually read is referred as the non-recording rain gauges. Over time, the rain gauges are replaced

or supplemented with automatic rain gauges, thus variation in rainfall intensity can also be

recorded. In the automatic rain gauge, there are recording devices or loggers attached to register

rainfall and its time of occurrence. So far, there are limited rainfall gauges. Most of the automatic

rain gauges are tipping bucket, weighing and radar types.

2

Non Recording Rain gauge

There are two non-recording rain gauges used by JPS Malaysia;

i. 203 mm diameter rain gauge, which is referred as manual gauge and readings are

taken daily or weekly

ii. 127 mm diameter rain gauge with capacity to collect 4000 mm of rainfall, used to

check gauge and readings are taken monthly. This is installed in stations located in

remote areas.

The standard rain gauge, has a 203mm or 127mm diameter receiver cap on top to catch and

funnel the rain into a can. The receiving funnel has a knife edge to catch rain falling precisely

in the surface area of 203 mm or 127 mm diameter. Measurements are done by pouring the

rainwater collected in the rain gauge into a measuring cylinder. The standard measuring

cylinder is 381 mm in height and has internal diameter of 76.2 mm. It is developed by JPS to

be used with the 203 mm diameter rain gauge. The cylinder is graduated to 1 and 0.5 mm,

it is intended to read the depth of the rain collected without having to apply any factors.

The cylinder has a convex base to enable reading of rainfall less than 0.5 mm. The water

level in the measuring cylinder is determined from the bottom level of the meniscus.

Usually, the rain gauge is installed at a standard height of 1350 m above the ground,

equipped with windshield to reduce the wind turbulence effect so that the rain gauge

catchment storage capacity is not affected.

Recording Rain Gauge

Daily readings of rainfall do not provide information of the rainfall temporal distribution and

it does not give details like how intense is the rainfall over short time period, this information

is critical to design urban drainage and flood simulation systems. The tipping bucket rain

gauge solves the issue in recording rainfall intensity and temporal distribution and the DID’s

rainfall stations were replaced with this type of recorder. Its description is given in detail in

the Hydrology Manual - Revised and Updated 1988.

In the 80s, the tipping was recorded on paper charts but this soon gave way to digital

recordings in memory chips. Paper charts have to be digitised to convert it to digital form

and this is time consuming. The digital recordings have the advantage to provide the data in

digital form in an instant. With digital recordings in memory chips, there is no more

difference between weekly and long-term recording equipment, as data storage is no longer

3

a constraint and all automatic recorders are now recording long-term data. All automatic

(long-term) recording stations have a manual station that acts as a check gauge. In the

weekly rainfall stations, the check gauge has smaller capacity. The long-term recording

station has larger storage of a check gauge.

Tipping Bucket

The tipping bucket type rain gauge consists of a funnel that collects and channels the

precipitation into a seesaw-like container. After a pre-set amount of precipitation falls, the

lever tips, dumping the collected water thus sending an electrical signal. The electrical digital

signal will then be connected to data logger or Remote Terminal Unit (RTU) to log as a rainfall

tip (the amount of tip depends on rain gauge size).

200 mm Diameter with 0.5 mm Capacity

The 0.5 mm tipping bucket is currently used as the main rainfall measurement instrument

for almost all hydrology rainfall stations nationwide. The integrated siphon mechanism has

high accuracy across a broad range of rainfall intensities. Each unit consists of a collector

funnel with leaf filter, an integrated siphon control mechanism, an outer enclosure with

quick release fasteners, and base which houses the tipping bucket mechanism device. The

unit also includes dual output reed switches with varistor protection as well as dual rainfall

discharge outlets for water collection and/or analysis. All of the rain gauges are installed

using 0.5 mm bucket capacity. Overall, rainfall sensors at the rainfall stations are in a good

working condition and can provide rainfall data to JPS.

The tipping bucket rain gauge is not as accurate as the standard rain gauge because the

rainfall may stop before the lever tips. When the next rain occurs, it may take no more than

one or two drops to tip the lever. This causes the pre-set amount of rainfall falls when in

fact, only a fraction of that amount has actually fallen. Tipping buckets also tend to

miscalculate the rainfall amount, especially during heavy rainfall. The advantage of the

tipping bucket rain gauge is, it enables the characterisation of the rain (light, medium, or

heavy). Rainfall character is decided by measuring the total amount of rainfall in a specific

period (usually 1 hour) and counting the number of 'clicks' in 10 minutes, for an observer to

deduce the rain characteristics. In the event of high intensity rainfall, the data algorithms

can be corrected.

4

Nano hydrophobic coatings are sprayed on liquids used to protect glass, ceramic, painted,

metal, fabric, wood and mineral surfaces with oleophobic, water-stain repellent and

superhydrophobic features. This provides the surface with water repellence, oleophobic

coating, stain repellence, scratch resistance and water proofing characteristics. Thus,

nanocoating should be applied to the outer side of tipping bucket for extra protection.

Weighing Gauge

According to the Guide to Meteorological Instruments No. 8 (WMO 2014), in these

instruments, the weight of a container and the precipitation accumulated therein, is

recorded continuously, either by means of a spring mechanism or a balance weight system.

All precipitations, both liquid and solid, are recorded as the fall. This type of gauge normally

has no provision to empty itself; the capacity (namely, the maximum accumulation between

recharge) ranges between 250 and 1500 mm, depending on the model.

Low-capacity models should be avoided in areas where the maximum accumulation can

occur over short time period. The gauges must be maintained to minimise evaporation loss,

which is accomplished by adding sufficient oil or evaporation suppressants inside the

container, to form a film over the water surface. Any difficulties in balancing strong wind

oscillation is reduced via microprocessor programming to avoid readings from being

affected.

Figure 1 Typical Tipping Bucket

5

Such weighing gauges (Figure 2) are useful in recording snow, hail, as well as mixture of

snow and rain, since the solid precipitation does not need to be melted before being

recorded. The instrument does not use any moving mechanical parts in the weighing

mechanism; only elastic deformation occurs. Therefore, mechanical degradation and the

need for maintenance are significantly reduced.

Figure 2 Typical Weighing Gauge

In general, the digitised output signal is averaged and filtered. Precipitation intensity is

calculated from the difference between two or more consecutive weight measurements.

The accuracy of this gauge depends on the measurement and/or recording characteristics,

which can vary between manufacturers. Many instruments have data output with

diagnostic parameters, which are useful for further evaluation of measured data and data

quality control.

Errors and correction

Except for the errors due to the wetting loss in the container when it is emptied, weighing

gauges are susceptible to other sources of error. Another common fault with weighing

gauges is wind pumping. This occurs during high winds when turbulent air currents flow

around the catchment container, causing oscillation in the weighing. Errors associated with

anomalous recordings can be minimised by averaging readings over short time intervals,

usually ranging from 1 to 5 minutes. Timing errors in the instrument clock assign the catch

to the wrong period or date. Some weighing gauges also exhibit temperature sensitivity in

the weighing mechanism that adds a component to the output, which is proportional to the

diurnal temperature cycle.

6

Some potential errors in manual precipitation measurement are minimised by using

weighing gauges. Random errors associated with human error and systematic errors, such

as evaporation and wetting loss are minimised. In some countries, trace observations are

given a value of zero, thus resulting in a biased underestimate of the seasonal total

precipitation. This is minimised with weighing gauge, since the small amount of precipitation

will accumulate over time.

A fundamental characteristic of weighing gauges in measuring precipitation intensity is the

response time (filtering process included), which leads to measurement errors (systematic

delay). The response time, which is available in operation manuals or evaluated during the

previous WMO inter-comparison (WMO, 2009), are in the order of six seconds to few

minutes, depending on the gauge's design and model. The 1-minute precipitation intensity

resolution is different between weighing gauges and depends on the transducer resolution.

Such gauges may exhibit a limited or discriminatory threshold for precipitation intensity.

The correction of weighing gauge data on hourly or daily basis is more difficult than longer

collection period, such as monthly climatological summary. Ancillary data from automatic

weather stations, such as wind at gauge height, air temperature, present weather or snow

depth, are useful in interpreting and correcting the automatic gauge precipitation

measurements. The specification of weighing tipping bucket is illustrated in Table 1.

Table 1 General Specification of Weighing Type Tipping Bucket

Item Specification

Recordable

precipitation

Liquid, solid and mixed

Collecting area 200 cm3

Sensor element Sealed load cell

Measuring range Precipitation: 0…3000 mm/h

Accuracy Amount: +- 0.1 mm or +-1% of measured value

Intensity: +- 0.1 mm/min or +-1% of measured value

Power Supply 5.5… 28 V DC, typically 12 VDC secured against reverse polarity

Protection Pipe housing closed: IP65

Pipe housing open: IP63

Load cell: IP68

7

Radar

A weather radar is used to locate precipitation, calculate its motion, estimate its type (rain,

snow, hail, etc.) and forecast its future position and intensity. The most common weather

radars are Doppler, which can detect the motion of rain droplets besides the precipitation

intensity. Both data types can be analysed to determine the structure of storms and their

potential to cause severe weather.

For real-time use, this radar provides a unique mean of obtaining widespread, spatially

continuous measurements of precipitation location and intensity at scale of hundreds of

metres. Rainfall radar products are directly used by weather forecasters, and are fed into

forecasting models. In the areas of aviation and flood forecasting, they are crucial to protect

life and property.

Each radar sends out microwave radiation pulses and detects the return signals reflected by

precipitation particles, either liquid or frozen (Figure 3). The strength of the return signal is

used to estimate precipitation intensity, and its delay is a measure of distance from the radar

site. The radar generates polar (circular) measurement maps by 360 degrees rotation at

azimuth base, while transmitting pulses concentrated in a narrow beam. Some of the ‘scans’

are taken at a number of low elevation angles above the horizon. A scanning cycle takes 5

minutes, providing data up to 255 km from the site with a resolution up to 1 km.

Figure 3 How a Rainfall Radar Works (Met Office UK 2017)

https://www.metoffice.gov.uk/learning/making-a-forecast/first-steps/making-observations/rainfall-radar

8

In 2010, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) of Japan

developed X-band multi-parameter radar known as XRAIN for flood forecasting, equipped

with high resolution and quasi real-time observation in urban areas to reduce damage from

localised heavy rain and torrential downpour (Figure 4).

XRAIN real time information is delivered to the public via the MLIT website. Application and

contents for mobile devices are developed by the private sector and are widely used. When

heavy rain exceeds a specified value, MLIT sends alert via email to concerned individuals for

disaster prevention.

The summarised characteristics of XRAIN are as below (MLIT 2013):

(i) High resolution - X-band radar has short wavelength and can be observed at high

resolution (8-12 GHz)

(ii) Real Time - Measure shape of raindrops by transmitting two type of waves (horizontal

and vertical) and estimate rainfall from flattening of raindrops.

(iii) Suitable for rainfall prediction - Enable the user to observe raindrop in moving

direction and speed by Doppler Effect

Figure 4 X-Band MP Radar at Funabashi, Japan 9 (MLIT 2013)

9

3. Procedure in Selecting Rainfall Gauges

The radar rain gauge is known for real time and are very costly. Automatic rain gauge consists of

recording devices such as data loggers connected to either tipping bucket or weighing gauges system

device. The weighing gauge are useful in recording snow, hail as well as mixture of snow and rain.

Therefore, tipping bucket type is more suitable to be used in Asian country.

According to New Zealand National Environmental Monitoring Standards (NEMS), resolution of

tipping bucket rainfall gauges as per below:

i. 0.5 mm in general

ii. 0.1 mm or 0.2 mm in catchments < 25 km2

iii. 1.0 mm in high rainfall, mountainous areas.

Currently, JPS Malaysia adopts 0.5 mm tipping bucket.

4. Selection of Site

Location of the rainfall station is important and therefore, due consideration should be given to the

following criteria in selecting the site;

i. The spot at which rain gauge is to be installed should truly represent the area, of which it is

supposed to give depth of rainfall.

ii. The rain gauge station should be accessible to the observer at all times.

iii. The gauge should be erected on level ground, not upon a slope or terrace.

iv. A position sheltered from the wind is preferable over an exposed one (in mountains and

near sea coasts, it is essential to ensure that the gauge is not exposed to the wind).

v. The gauge should be properly secured and locked.

vi. The rain gauge station should not be too close to the buildings or trees etc. the proximity of

such objects affects the entry of rainfall into the funnel. According to the Guide to

Meteorological Instruments No. 8 (WMO 2014), rain gauge distance from other objects

should not be less than twice the height of the object above the rim of the gauge.

10

5. Instrumentation

A standard list of instruments to be installed in a rainfall station is as follows:

i. Tipping bucket

ii. Windshield (optional)

iii. Pole stand

iv. Data logger

v. Manual rain gauge

General Specification of Tipping Bucket

The 0.5 mm tipping bucket is used as the main rainfall measurement instrument for most of

hydrology rainfall stations throughout Malaysia. General specifications of tipping bucket are

as below;

Receiver : 200mm+/- 0.3 diameter heavy duty cast aluminum, powder coated

Bucket Capacity : 0.5 mm of rainfall

Sensitivity : one tip

Maximum

intensity

: 700 mm/hr

Humidity : 0 – 100%

Temperature : -20 to +70 °C

Contact system :-Dual reed switches potted in soft silicon rubber with varistor

protection

Max capacity : 24V (0.5 amps max)

Resistance : Initial contact resistance 0.1 Ω

Syphon : 0.4mm (12ml) capacity of rainfall

Bucket : Synthetic ceramic coated brass bucket balanced to +/- 0.05gms

Base : Cast aluminum

Level : Bull’s eye level adhered to aluminum base

Mounting holes : Three 10mm diameter mounting holes with 117 mm p.c.d cast in

feet attached to the base outer diameter.

11

General Specification of Windshield

Windshield is made of zinc painted with aluminium oxide. Refer Appendix B: List of Drawing;

Drawing No: BSAH/HP32/TB/01 for arrangement installation. Experiments were carried out

by the Hydrology Division to study the impact of JPS’s standard windshield on rainfall

catchment since wind turbulence is the major factor affecting the catch of rainfall by rain

gauges (Water Resource Publication No. 14, 1984). However, the results showed that the

undercatch is only 1% for rain gauge without windshield, which is installed according to the

JPS standard, with the height of 1350 mm. Thus, windshield is optional, however, a

windshield will help to;

i. ensure a parallel air flow over the orifice of the gauge

ii. avoid local acceleration above the orifice, and

iii. reduce the velocity of the wind striking the sides of the gauge.

General Specification of Pole Stand

General specifications of pole stand are as below:

Detail drawing as shown in Appendix B: List of Drawing; Drawing No: BSAH/HP32/TB/02.

Pole Material : Hot dipped galvanised iron

Pole Height : 990 mm

Diameter Pole : 90 mm with hollow circular section

Pole Thickness : 700 mm/hr

Plate Thickness : 6 mm

Plate Diameter : 250 mm

Plate Material : Hot dipped galvanised iron

Footing : 300 x 300 x 300 mm concrete footing (concrete grade 25)

12

General Specification of Data Logger

A data logger (known as data recorder) is an electronic device that records data over time

or in time series, either with a built-in instrument/sensor or via external instruments &

sensors. They are based on digital processor (or computer). In general, they are small,

battery powered, portable, and equipped with a microprocessor, internal memory for data

storage, and sensors. Some data loggers can interface with a personal computer and utilise

software to be activated to view and analyse the collected data, while others have a local

interface device (keypad, LCD) for them to be used as a standalone device. General

specifications of data logger are as below;

Low Power consumption : 3.6 V lithium lasts up to 2 years

Optional External Power : 6-16 VDC

Inputs Monitoring : 1 x Digital Rain gauge, 1 x External Battery Voltage

Data Memory : 512 KB Serial Flash EPROM

Events Recorded : 100,000 events, 1 Second Resolution

Communications : RS232 Port, (Tx, Rx)/ USB/ Ethernet / Wi-Fi

Environmental : -40C to + 70C at 95% RH Non

General Specification of Manual Rain Gauge

The optional manual rain gauge (Refer Appendix B: List of Drawing; Drawing No:

BSAH/HP32/NR/01) may be installed in the rainfall station. The function is to manually check

the water collected in the can. The standard measuring cylinder is 381 mm in height and has

internal diameter of 76.2 mm). It is developed by JPS to be used with the 203 mm diameter

rain gauge. The cylinder is graduated to 1 and 0.5 mm, it is intended to read the depth of

the rain collected without having to apply any factors. The cylinder has a convex base to

enable reading of rainfall less than 0.5 mm. The water level in the measuring cylinder is

determined from the bottom level of the meniscus.

http://en.wikipedia.org/wiki/Scientific_instrumenthttp://en.wikipedia.org/wiki/Sensor

13

6. Construction of Station

Station

At first, the site should be cleared by getting shrubs, grass and overgrowth weeded out.

Then the site should be levelled. The fencing should be constructed according to the

specifications and dimensions shown in Appendix B: List of Drawing; Drawing No:

BSAH/HP32/FEN/01.

There are two type of rainfall station construction in JPS. They are ground level installation

and roof top installation. For installation at the ground level, it is essential that each

instrument installed at the station does not affect the exposure of other instruments: e.g.

the enclosure should not affect rainfall collection in the rain gauge. The detailed layout of

the installation is shown in Appendix B: List of Drawing; Drawing No: BSAH/HP32/GA/01.

Roof top installation are done by installing tipping bucket with pole stand wall plugged to

roof slab. The enclosure will be placed indoor as shown in Figure 5. This is practiced for

combine stations where there will be two sensors or parameters being measured.

The construction should be done with care to avoid excavated earth being thrown onto the

levelled site. It is advisable to check the site level once the fencing has been constructed.

Figure 5 Tipping Bucket Installed at the Top of Station Housing

14

Enclosure

The enclosure should be water resistant with ingress protection of IP65 and complete with

compartment for manual. Also, it needs to be tidied up and maintained in good condition

all times. For future installation, it is recommended that JPS specifies the use of epoxy

coated galvanised enclosures.

Cable gland are used to attach and secure the end of the electrical cable. Cable gland

provides strain relief and connects with suitable cable for which it is designed, including

electrical connection to the armour or braid and lead or aluminium of the cable sheath, if

any. Rubber seal gaskets need to be replaced frequently, to ensure that the enclosure is not

accessible by insects or small rodents. Moreover, the wiring inside the enclosure need to be

terminated with suitable ferrule, flexible conduits, cable ties and labelled accordingly.

Finally, the enclosures on-site need to be provided with troubleshooting manuals, such as

wiring diagrams, operation & maintenance manual as well as as-built drawings. All

equipment on site should be labelled accordingly to make the troubleshooting easier. The

enclosure is sealed with JPS logo and marked with “HAK MILIK KERAJAAN MALAYSIA”.

Earthing

Every building, equipment, power plants, substations and facilities that use electricity

require earth grounding, either directly or through a grounding system. By definition, the

earthing system that is sometimes called ‘earthing’, it means the total set of measures used

to connect electrically conductive part to earth. Figure 6 illustrates the earthing and

protective conductor system. The earthing system is an essential part of power networks at

both high- and low-voltage levels. In this system, we are going to use voltage less than 1 Ω

and the installation of Surge Protection Device (SPD) 7 step is necessary for overvoltage

protection. In general, a good earthing system is required to protect station buildings and

installations against lightning, safeguard human and animal life by limiting touch and step

voltage to safe value, rectify operation of the electrical supply network and ensure good

power quality.

15

Figure 6 Illustration for Earthing and Protective Conductor System

16

The ground system resistance is tested beforehand to provide a concrete proof that the

preliminary design assumption is accurate and the earthing system is adequate and effective

in protecting rainfall station system. Besides, ground resistance measurements are to verify

the new ground system adequacy and determine ground potential rise (GPR) in developing

protection for power and communication circuits. In designing an earthing system, the

system shall provide low impedance path to ground for personnel and equipment

protection, as well as circuit relaying and it shall withstand and dissipate repeated fault and

surge current.

Overall, the earthing system is essential to complete an electrical path to ground if there is

non-designed or unanticipated above-normal potential current or voltage surge during

operating conditions. Personal injury, death or equipment damage can happen if the

grounding system is not properly designed and installed to guide the potentially dangerous

charge safely to ground. Furthermore, the earthing system under normal conditions carries

no current. It only carries current under abnormal conditions, when an electrical appliance

or equipment is faulty, and becomes a potential shock or fire hazard.

In conclusion, it is important for the earthing system at rainfall station to be inspected,

tested and reviewed periodically, so that all components are protected from hazard or

damage, thus ensuring data collection for rainfall measurement runs continuously.

BS 7671 lists five types of earthing system: TN-S, TN-C-S, TT, TN-C, and IT.

• T = Earth (from the French word Terre)

• N = Neutral

• S = Separate

• C = Combined

• I = Isolated

17

TN-C System

• Neutral and protective functions combined in a single conductor in a part of the system.

• The usual form of a TN-C-S system is as shown (Figure 7), where the supply is TN-C and

the arrangement in the installations is TN-S.

• This type of distribution is also known as protective multiple earthing.

• The supply system PEN conductor is earthed at two or more points and an earth

electrode may be necessary at or near a consumer’s installation.

• All exposed-conductive-parts of an installation are connected via the main earthing

terminal and the neutral consumer’s installation.

Figure 7 TN-C System

TN-S- System

• Separate neutral and protective conductors throughout the system (Figure 8).

• The protective conductor (PE) is the metallic covering of the cable supplying the

installation or a separate conductor.

• All exposed-conductive-parts of an installation are connected to this protective

conductor via the main earthing terminal of the installation.

18

Figure 8 TN-S- System

TN-C-S System

• Neutral and protective functions combined in a single conductor in a part of the system.

• The usual form of a TN-C-S system is as shown (Figure 9), where the supply is TN-C and

the arrangement in the installations is TN-S.

• This type of distribution is known as protective multiple earthing.

• The supply system PEN conductor is earthed at two or more points and an earth

electrode may be necessary at or near a consumer’s installation.

• All exposed-conductive-parts of an installation are connected via the main earthing

terminal and the neutral terminal, these terminals being linked together.

Figure 9 TN-C-S System

19

T-T System

• All exposed-conductive-parts of an installation are connected to an earth electrode

which is electrically independent of the source earth (Figure 10).

Figure 10 TT-System

IT-System

• All exposed-conductive-parts of an installation are connected to an earth electrode

(Figure 11).

• The source is either connected to earth through a deliberately introduced earthing

impedance or is isolated from earth.

Figure 11 IT-System

20

Lightning Protection

The lightning protection system shall be provided where necessary based on site condition.

It shall include air termination network, down-conductors, joints and bonds, testing joints,

lightning flash counter, earth termination, earth electrodes and accessories incidental to the

whole system (Refer Appendix B: List of Drawing; Drawing No: BSAH/HP32/ELP/01).

Air termination network shall consist of a network of vertical and horizontal conductors, as

shown in the drawing. Whether shown in the drawings or not, all metallic projections,

chimneys, ducts, gutters, vent pipes, guard rails, aerial masts on or above the main surface

of the roof of the structure shall be bonded to and form part of the air termination network.

Other than air terminal or vertical finial, air termination network shall be of 25 mm x 3 mm

annealed copper tape. The method and nature of the fixing shall be simple, solid and

permanent. Air terminal or vertical finial shall be having rounded end and made of copper.

They shall be 300 mm in length and 16 mm diameter with lock nut. Down conductors shall

be 25 mm × 3 mm bare annealed copper tape, installed around the walls outside of the

structure.

The lightning protection system should have as few joints as possible. Joints and bonds shall

be mechanically and electrically effective, via copper clamps, welding, soldering or brazing.

Contact surface shall first be cleaned then protected against oxidation with a noncorrosive

compound. Each earth termination shall be connected to a down-conductor. Earth

termination shall be made by 25 mm x 3mm annealed copper tape, connecting the down

conductor at the testing joint to the earth electrodes.

All measuring and test instruments used for lightning protection system installations shall

be regularly tested and calibrated by manufacturers or calibration laboratories, to preserve

their functionality and accuracy at the rainfall station. This is followed by the installation of

Surge Protection Device (SPD) 7 Steps in the lightning protection system. SPD is an electrical

installation protection component. This device is connected parallel to the power supply

circuit of the load that it has to protect. It is also used at all power supply network levels. It

is the most efficient overvoltage protection. SPD is designed to limit transient overvoltage

of atmospheric origin and divert current wave to earth, to limit the overvoltage amplitude

to a value that is non-hazardous for the electrical installation, electric switchgear and control

gear.

21

SPD eliminates overvoltage in the following ways;

i. common mode, between phase and neutral or earth;

ii. differential mode, between phase and neutral.

iii. in the event of an overvoltage exceeding the operating threshold, the SPD conducts

the energy to earth, in common mode; and

iv. Distributes the energy to the other live conductors, in differential mode.

SPD is classified into 3 types, namely Type 1, Type 2 and Type 3. The Type 1 SPD is

recommended in service-sector and industrial buildings, protected by a lightning protection

system or meshed cage. It protects electrical installation against direct lightning stroke. It

discharges the lightning back-current from the earth conductor to the network conductors.

Type 1 SPD is characterised by 10/350 µs current wave. The Type 2 SPD is the main

protection system for low voltage electrical installation, installed in electrical switchboard,

to prevent the spread of overvoltage in electrical installation and protect the loads. Type 2

SPD is characterised by 8/20 µs current wave, with low discharge capacity. Therefore, they

must be installed as a supplement to Type 2 SPD and in the vicinity of sensitive load. Type 3

SPD is characterised by a combination of voltage wave (1.2/50 µs) and current wave (8/20

µs).

International standard IEC 61643-11 Edition 1.0 (03/2011) defines the characteristics and

tests for SPD connected to low voltage distribution system into three characteristics. The

first characteristic is Uc, which is the maximum continuous operating voltage where A.C. or

D.C. voltage is above which the SPD becomes active. This value is according to the rated

voltage and earthing arrangement. Another characteristic is Up, the voltage protection level

(at In). This is the maximum voltage across the SPD terminals when it is active. This voltage

is reached when the current flowing in the SPD equals to in. The voltage protection level

must be lower than the load overvoltage withstand capability (see section 3.2). In the event

of lightning stroke, the voltage across the SPD terminals remains lesser than Up. The last

one is In, the nominal discharge current where the peak current value is 8/20 µs waveform,

this is when the SPD can discharge for 15 times.

22

Conduit

Rainfall station consist of electrical components connected in a system to operate as JPS

data collection station. This system requires proper wiring and conduit system to make

maintenance work easier, in terms of fault detection and repair. In general, wiring and

conduit system is an electrical distribution connected through wires, which use wiring

conductors inside a room or building with better load control at rainfall station. Therefore,

PVC conduit wiring is recommended to be installed to connect electrical instrument and

enclosure board (Refer Appendix B: List of Drawing; Drawing No: BSAH/HP32/EC/01).

In addition, PVC conduit wiring has advantages such as being cheap and easy to install and

customise, strong and durable. In fact, PVC conduit wiring installed on roof or wall is known

as surface conduit wiring. In the conduit wiring system, the conduits should be electrically

continuous and connected to earth at suitable points, in case of steel conduit. The conduit

protects the cables from being bitten by rodents, which will result in short circuit.

In the external wiring system, it is recommended to use GI pipes as protection. External

wiring will cause further damage due to activities such as vandalism, theft and excavation

work. To install GI pipe, marking point shall be marked according to designed drawing and

laid underground. In addition, marking signage shall be provided along GI pipe to notify the

existence of wiring line.

For voltage drop in consumer installation, in the absence of any consideration, under normal

service condition, the terminal voltage of any fixed current-using equipment shall be greater

than the lower limit of the equipment standard. The fixed current-using equipment is not

subjected to product standard, thus the terminal voltage shall not impair the equipment

safety. These requirements are satisfied if the voltage drop between the origin of the

installation (usually the supply terminals) and socket-outlet or terminals of the fixed current-

using equipment does not exceed;

Requirements Lighting Other Uses

Low voltage installations supplied directly from a public low

voltage distribution system

3% 5%

Low voltage installation supplied from private LV supply (*) 6% 8%

23

A voltage drop greater than the amount stated above is acceptable for a motor during

starting period and equipment with high inrush current, provided that the voltage variation

is verified within the limit specified in the equipment product standard or, in the absence of

product standard, it should be in accordance with the manufacturer recommendations.

Fencing

The type of fencing should be chosen depending on the area. The construction should be

done with care to refrain excavated earth from being thrown onto the levelled site. It is

advisable to check the site level once fencing has been constructed.

Type of Fencing

Type of fencing used are:

i. Security fence

ii. Anti-Climb Fence

iii. Chain-link fence

Security Fence

Security fence, also known as roll top fence (Figure 12) is a hot dipped galvanised iron

welded mesh panel that provides see-through security, with contemporary design. It has

spacing specification of 50 mm × 150 mm, making the place looks safe and elegant. The

fence is designed with a triangular roll on the top and bottom parts, thus making it stronger

and tougher. With wire thickness of 5 mm and 50 mm × 150 mm spacing, the roll top fence

is very strong, hard to be bent. Hence, this prevents anyone from climbing over the fence to

reach the protected area.

Figure 12 Security Fence

24

Anti-Climb Fence

Anti-climb fence is the heavy duty hot dipped galvanised iron welded mesh panel with toe

and finger proof profile, this provides the highest degree of see-through security. With

spacing specification of 75 mm × 12.5 mm, which makes it impossible for fingers and toes

to go through, this prevents anyone from climbing over the fence to reach the protected

area. The fence is known as anti-cut fence as it is difficult to cut through the panel with

simple hand tools. With wire thickness of 4 mm and 75 mm × 12.5 mm spacing, intruders

can never cut off the fence.

Figure 13 Anti-Climb Fence

Chain Link Fence

Chain link fence is the most economical and oldest fence available in the market. The chain

link fence (also referred to as wire netting, wire-mesh fence, chain-wire fence, or diamond-

mesh fence) is made of thick steel wire and has a diamond-shaped pattern, often galvanised

or PVC wire is used for this fence.

Figure 14 Chain-link Fence

25

Comparison of Type of Fencing

Table 2 shows the comparison between fencings. Different fences are used, depending on

the rainfall station area.

Table 2 Comparison of Different Type of Fencing

Type of

Fence

Perimeter Size

(w x l x h) (m)

Cost Safety Effect to the

Data Quality

Ease of

Installation

Chain Link 3 x 3 x 1.3 Lowest Lowest No Easy

Safety Fence 3 x 3 x 1.3 Moderate Moderate No Easy

Anti-climb 3 x 3 x 2.5 Highest Highest Yes Hard

Signboard

General specifications of signboard are as below:

Plate Material : 1300 mm x 1000 mm aluminium plate

Frame Material : 50 mm x 25 mm hollow section mild steel

Pole material : 50 mm diameter mild steel pipe

Reinforcement : 30 mm x 30 mm x 30 mm angle section (anchor)

The detailed drawings and wordings are depicted in Appendix B: List of Drawing; Drawing

No: BSAH/HP32/SB/01.

7. Installation of Instrument

Installation of Tipping Bucket

Installation of tipping bucket must adhere to but not limited to the following procedures;

1. Perform installation work based on the DID Hydrology Manual (DIDM) 2009 and

manufacturer installation manual.

2. The height of tipping bucket must 1.35 m from the ground level or concrete, to the

top part of tipping bucket.

3. The foundation of the tipping bucket pole must be made of concrete (300 mm × 300

mm × 450 mm) and buried underground, subjected to the soil condition.

4. Test the instrument according to procedure and prepare installation and

maintenance report.

26

Installation of Mini Data Logger

Installation of mini data logger must adhere to but not limited to the following procedures;

1. Ensure the mini data logger and input cable are tested by qualified personnel before

installation at site.

2. Connect input cable to mini data logger as per manufacturer’s manual.

3. Key in the parameters and station information into data logger.

4. Test to ensure data is received and stored by mini data logger.

5. Ensure that one tipping bucket cable output is only for one input cable (sharing is not

allowed)

6. Delete test data before leaving the station.

8. Solar Power Supply

The calculation of the power consumption for the Hydrological Standard of Rainfall Station

Instrumentation is as below;

Total Amp Hour consumption for Enclosure including running of a (1) Tipping Bucket, one (1) Data

Logger, one (1) Telemetric Equipment, one (1) Power Supply and related components in enclosure

= 1.4 Amp

Thus, total Power Consumption (PC) for 24 Hours,

PC = V x AH = 12 x (1.4 x 24 hours) = 12 x 33.6 = 403.2 WH

Total Power Consumption for 24 hours, PT = PC = 403.2 WH

Total Sunshine Hour = 4 Hours,

Efficiency of Solar Panel Charging = 0.85

Thus, total solar power (100W) required to charge the battery

= (403.2) / (100 x Sunshine hour x Efficiency of solar charging)

= (403.2) / (100 x 4 x 0.85)

= (403.2 / 340)

= 1.18 (value more than 1)

= 2 pieces of 100W Solar Panels.

From the calculation, it shows that 2 pieces of 100W solar panel are needed to recharge the battery

every day, with around 40% of reserve. This is to make sure that the power is enough during rainy

day.

27

The calculation to prove that the system is sufficient for 14 non-sunny days.

Thus, total Ampere Hour Consumption for 24 hours,

AHC = 24 x 1.4 = 33.6 AH

And total Ampere Hour Consumption for 14 days,

AH4D = 14 x 33.6 = 470.4 AH

5 unit of 100Ah battery shall be used as power storage and power backup.

Thus, total Ampere Hour available from batteries, AHB = 100 x 5 = 500 AH.

Total Power Reserve Available = AHB – AH4D = 500 – 470.4 = 29.6 AH

From the calculation, this shows that power consumption is sufficient for 14 non-sunny days, with

5 units of 100 Ah battery as power storage and backup system. The total power reserve available

from the design is 29.6 Ah, which is around 5.92% of the total power storage of 500 Ah.

9. Telemetry and Communication System

Remote Terminal Unit (RTU)

A remote terminal unit (RTU) is a microprocessor-controlled electronic device interface

objects in the physical world to a distributed control system or supervisory control and data

acquisition system (SCADA) by transmitting telemetry data to the system and/or altering the

connected objects based on control messages received from the system. With the low

power consumption concept, it has been successful in monitoring and control system

applications. RTU can directly interface with most of measuring instrument present on site.

Table 3 shows the summarized general specification of the RTU.

Table 3 Technical Specification of RTU

Capability • Long-term data telemetry, data collection, monitoring and

control of Real Time Data Management and Telemetry

System

• Automatic and reliable data logging, alarm reporting and

transmitting of collected telemetry data to Telemetry

Gateway Server

Internal Data Storage Minimum of 125MB

http://en.wikipedia.org/wiki/Microprocessorhttp://en.wikipedia.org/wiki/Distributed_control_systemhttp://en.wikipedia.org/wiki/SCADAhttp://en.wikipedia.org/wiki/Telemetry

28

Real-time Clock Yes

Communication

Interfaces

• Ethernet Port

• USB Port

• Host RS232 Port

LCD Display Yes

Power • External Power of 10-24VDC

• Internal Battery

Humidity Up to 70% RH

I/O Module Minimum of 4DI, 2DO, 5AI

Protocols supported Modbus, FTP, HTTP, XML, SMTP, NTP and SDI-12

Bulit-in Software and

Application

• The software shall be built in without no major application

installation is required.

• Easy to configure, interactive interface, able to access live

and historical data.

• The application shall be used to collect, automate and

transmit the data telemetrically with the connected or built

in 3G/GPRS Modem.

29

Communication Instruments

Communication devices modems are important in a telemetry system to transmit data from

on-site RTUs to its master station for data processing, display and archiving purposes. In

general, there are three telecommunication mediums used as the communication media for

the hydrology telemetry system, they are radio communication, GSM/GPRS communication

and satellite communication.

Radio Communication

Radio modem is a modern way to create private radio network (PRN). PRN is used in

industrial critical applications, when real-time data communication is required. Also, radio

modem enables users to be independent of telecommunication or satellite network

operators. Users use licensed frequency, either the UHF or VHF band. VHF band is utilised

as the radio communication channel medium for the telemetry system. Licensed frequency

is reserved for users in certain area, thus ensuring that there is lesser radio interference

from other RF transmitters. The Tait radio modem is used as the radio communication

modem for telemetry systems, using radio VHF communication and the specification is

summarised in Table 4.

Table 4 Summary of Specification of VHF Band

Channels Frequency Ranges Supply Voltage Transmitter Power

4 (Simplex or

semi-duplex)

Channel

Spacing

12.5 kHz

20 kHz

25 kHz

66-88 MHz

136-174 MHz

175-225 MHz

220-270 MHz

330-360 MHz

360-400 MHz

400-470 MHz

450-520 MHz

500-530 MHz

800 MHz: 806-870 MHz Tx

: 851-870 MHz Rx

900 MHz: 896-941 MHz Tx

: 935-941 MHz Rx

13.8 V nominal

10.8-16.0 V

range

25W

22.5W 500-530 MHz

15W 800 MHz, 900

MHz

http://en.wikipedia.org/wiki/UHFhttp://en.wikipedia.org/wiki/VHFhttp://en.wikipedia.org/w/index.php?title=RF_transmitters&action=edit&redlink=1

30

GSM/ EDGE Communication – 3G/4G

Global System for Mobile (GSM) Communications, originally Groupe Spécial Mobile, is a

standard developed by the European Telecommunications Standards Institute (ETSI) to

describe the second generation (2G) digital cellular network technology. Developed to

replace the first generation (1G) analog cellular network, the GSM standard originally

describes a digital, circuit-switched network optimised for full duplex voice telephony. The

standard was expanded over time to include first circuit-switched data transport, then

packet data transport via General Packet Radio Services (GPRS). GPRS is a best-effort service,

implying variable throughput and latency that depend on the number of users using the

service concurrently, as opposed to circuit switching, where quality of service (QoS) is

guaranteed during the connection. The enhanced data rate for GSM Evolution (EDGE) (also

known as Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC), or Enhanced data rate for

Global Evolution) is a digital mobile phone technology that improves data transmission rate

via a backward-compatible extension of GSM. EDGE is a pre-3G radio technology and is part

of ITU’s 3G definition.

Also, EDGE is standardised by 3GPP as part of the GSM family. Through the introduction of

methods such as coding and data transmission, EDGE delivers higher bit-rates per radio

channel, resulting in a threefold increase in capacity and performance as compared to

GSM/GPRS connection. EDGE is used for any packet switched application, such as an

Internet connection.

Satellite Communication

A communications satellite (sometimes abbreviated to COMSAT) is an artificial satellite

stationed in space for telecommunication purpose. Communications satellite use a variety

of orbits such as geostationary orbit, Molniya orbit, elliptical orbit and low (polar and

nonpolar) Earth orbit. For fixed (point-to-point) service, communication satellite provides a

microwave radio relay technology complementary to that of communication cable. Satellite

internet access is utilised as one of the communication methods in remote areas, where it

is difficult to deploy radio communication or GSM/GPRS communication.

http://en.wikipedia.org/wiki/Satellitehttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/Geostationary_orbithttp://en.wikipedia.org/wiki/Molniya_orbithttp://en.wikipedia.org/wiki/Elliptical_orbithttp://en.wikipedia.org/wiki/Polar_orbithttp://en.wikipedia.org/wiki/Point-to-point_%28telecommunications%29http://en.wikipedia.org/wiki/Microwave_radio_relay

31

10. Maintenance of Instruments

JPS headquarters will assist the state hydrological officer in carrying out the maintenance, repair or

calibration works. The data logger readings should be checked regularly with telemetric instrument.

If any appreciable error occurs between the two reading sets, the cause of error must be identified

and rectified.

Regular maintenance of the rainfall tipping bucket is essential in collecting good quality data.

Maintenance must comply with but not limited to the following items;

i. Cleanliness of equipment. The following items should be checked regularly for cleanliness:

a. Catch filter

b. Syphon

c. Interior of bucket

d. All insect screens

ii. Ensure Rain Gauge is level using the bubble level fitted to the base

iii. Enclosure locking screws - lightly lubricate after cleaning

iv. Conductivity of mercury switch and Pulse cable

v. Test tipping using portable calibrator for about 40 tips as recommended by manufacturer.

vi. Fill up TKUP 6 form as attached in appendix.

Maintenance of the rainfall recorder must comply with but not limited to the following item:

i. Cleanliness of equipment

ii. Date time starting

iii. Date time off

iv. Compare reading of recorder/ logger and telemetry

v. Battery reading

vi. Check connectivity with sensors

vii. Record any malfunction or missing date

viii. Fill up TKUP 7 form as attached in appendix.

ix. Fill up TKUP 9 for station with telemetry.

32

11. Calibration of Instruments

The purpose of calibration is to provide measurement accuracy. Rainfall gauge shall be calibrated at

the intensity(s) recommended by the manufacturer or as advised, in Malaysia, by an accredited

calibration agency. Gauge shall maintain its performance up to the measurement intensity.

According to Jadual Servis, Ujian dan Tentukuran Alat (JSUTA) from JPS ISO 2015, rainfall tipping

bucket is valid for five (5) years, afterwards, it needs to be calibrated at workshop.

Calibration Procedure

Calibration work must comply with but not limited to the following procedures:

1) The left volume vessel is filled with water and the 100 mm/hour nozzle is inserted.

2) Calibration is commenced by turning on the outlet valve and recording time using

stopwatch, after all the water is drained from the left volume vessel.

3) The procedure is repeated using 200 mm/hour and 300 mm/hour consecutively.

4) Similar procedures are repeated for right volume vessel.

5) Calibration is done based on the Hydrological Services Lab.TB- RG Calibration

Standard.

6) Fill in UT5 form as attached in appendix.

How and When to Calibrate

Rainfall gauge shall be calibrated in accordance with the methodology recommended by the

manufacturer or calibration agency;

1) when the instrument validation has failed to conform with the specifications, and

2) with frequency recommended by the manufacturer. Often, tipping bucket is

calibrated every five years at workshop and every three months on site using

calibrator.

33

12. Guidelines for Safety & Health

These guidelines are to protect workers from hazards and eliminate work-related injuries, ill health,

diseases, incidents and deaths. Table 5 summarises the hazard, risk and control during installation,

operation and maintenance works of rainfall station.

Table 5 Summary of Safety and Health Guidelines

Hazard Risk Control

Working at a height Falling • Planning

• Working at height safety programme

• Wearing safety harness

• Comply Factories and Machinery (Safety, Health and

Welfare) Regulations, 1970 – Regulation 12.

Insects bite Injury • Wearing long sleeves, trousers, and protective

footwear.

Working in hot

environment

Heat-related

illness

• work/rest cycles

• enough hydration

Site Tidiness

i. The site should be kept tidy.

ii. Walkways and stairs should be free from slipping and tripping hazards.

iii. There are no protruding nails on loose or fixed materials.

Working at Height

General Provisions

i. Ensure that working platform is secure and check that it;

(a) will support the weight of workers as well as materials and equipment they are

likely to use or store on it.

(b) is stable and will not overturn.

(c) is footed on stable ground or on stable support or structure.

ii. Provide guard rails, barriers at open edges, including floor edges, floor openings, roof

edges and working platform edges.

34

Guard Rails

Guard rails should;

i. be made from strong and rigid material to prevent people from falling and can

withstand other loads placed on them.

ii. be fixed to a structure, or part of a structure capable of supporting them.

iii. include;

(a) a main guard rail at least 900 mm above any edge, from which people tend to

fall.

(b) a toe board with at least 150 mm height.

(c) a sufficient number of intermediate guard rails or suitable alternatives.

iv. Risk of falling through opening or fragile material (e.g. roof lights) is reduced by

providing appropriate and adequate guard rails or barriers to cover the opening or

material.

Protective Equipment

Employers on construction site need personal protective equipment (PPE) to ensure their

safety and health such as;

Safety Helmet

i. Employees should be provided with safety helmets to protect their head from injury

due to falling, flying objects or striking against objects or structures.

ii. Employers should ensure that safety helmets are worn by the employees.

iii. When working at height, a strap should be used to prevent the safety helmets from

falling.

Footwear

i. Protective footwear should be worn by workers who are exposed to the risk of injury

of materials being dropped on their feet or nail, or sharp objects penetrating their

sole.

ii. When employees are working in water or wet concrete, they should wear appropriate

boots.

35

Working in Hot Environment

Excessive exposure to heat causes a range of heat-related illnesses, such as heat rash, heat

cramp, heat exhaustion and heat stroke. To reduce heat exposure and risk of heat-related

illness while working, practise work/rest cycle, drink water often, and provide an

opportunity for workers to build up tolerance level while working in the heat.

Electrical Hazard

Electrical hazard is defined as;

• A dangerous condition where a worker makes electrical contact with energised

equipment or a conductor, and from which the person may sustain injury from shock;

and/or

• the worker may face arc flash burn, thermal burn, or blast injury.

Electricity has the potential to cause serious injury and death. Electrical hazards exist in

contact with the exposed live parts, electrical faults are the source of ignition that initiates

fire or explosion.

Safety Procedures in Handling Electrical Equipment

i. Ensure only licensed or registered electricians carry out electrical work

ii. Switch off electrical supply before working on equipment

iii. Ensure tag out and isolation procedures are in place and used

iv. Ensure electrical equipment is in good working order (testing and tagging)

v. Use battery operated tools rather than main power tool where possible

vi. Remove damaged, unsafe electrical equipment or cords from the workplace

vii. Use residual current devices (or safety switches) with portable equipment (as per the

WHS Regulations)

viii. Don’t overload power sockets. Use power board not double adaptor.

ix. Meet electrical safety standards.

https://www.osha.gov/SLTC/heatstress/heat_illnesses.html

36

13. Do’s and Don’ts No Main Points Do’s Don’ts

1 Installation of

tipping bucket

• Install at flat land.

• Ensure minimum distance of

two times height from any

tree.

• Rain gauge shall not be deployed

on a slope and nearby the tree.

2 Maintenance • Carry checklist and enough

spare parts for maintenance

before a trip.

• Do not forget to fill in proper

checklist before leaving site.

• Do not compromise by not

changing the battery as

scheduled.

3 Personnel • Installation, maintenance

and calibration must only be

done by trained personnel.

• Do not go to site without

understanding the site safety

requirement as it may differ from

site to site.

4 Calibration • Follow calibration schedule

accordingly

• Do not use uncalibrated rainfall

gauge.

5 Power Supply

System

• Only use battery

recommended by

manufacturers.

• Solar system is not required for

rainfall station without telemetry.

37

14. Summary Sheet

1 INTRODUCTION This section describes about a standard and its aim.

2 REVIEW OF EXISTING

RAINFALL GAUGES

This section reviews current rainfall gauges that consist of non-

recording and recording rain gauges. The recording rain gauges

are tipping bucket, weighing and radar types. Currently JPS

adopts 0.5 mm tipping bucket.

3 PROCEDURE IN SELECTING

RAINFALL GAUGES

This section provides procedures in selecting rainfall gauge.

Currently, JPS adopts 0.5 mm tipping bucket.

4 SELECTION OF SITE This section explains criteria in selecting rainfall station site for

optimum reading.

5 INSTRUMENTATION This section provides a general specification of instruments to

be installed in a rainfall station is as follows;

(i) Tipping bucket

(ii) Windshield (optional)

(iii) Pole stand

(iv) Data logger

(v) Manual Rain Gauge

6 CONSTRUCTION OF STATION This section gives a brief explanation on other items set up at

rainfall station that include;

(i) Station housing

(ii) Enclosure

(iii) Earthing

(iv) Lightning Protection

(v) Conduit

(vi) Fencing

(vii) Signboard

7 INSTALLATION OF

INSTRUMENTS

This section provides information on installation of tipping

bucket and its logger.

38

8 SOLAR POWER SUPPLY This section explains that five (5) units of 100 Ah batteries as

power storage and backup system are sufficient for power

consumption within 14 non-sunny days.

9 TELEMETRY AND

COMMUNICATION SYSTEM

This section describes the technical specification of telemetry

as well as different communication mediums such as radio,

GSM 3G/4G, and satellite.

10 MAINTENANCE OF

INSTRUMENTS

This section provides information on maintenance procedures

of tipping bucket and its logger.

11 CALIBRATION OF

INSTRUMENTS

This section provides information on calibration procedures of

tipping bucket.

12 GUIDELINE FOR SAFETY AND

HELATH

This section provides brief guidelines on safety and health

during installation, operation and maintenance works.

13 DO’S AND DON’TS This section provides Do’s and Don’ts during installation,

operation and maintenance works.

39

15. References

1 World Meteorological Organisation; Guide to Hydrological Practices; Volume 1; Hydrology

–From Measurement to Hydrological Information. WMO-No. 168; Sixth Edition 2008

2 NEMS (2013) Rainfall Recording, National Environmental Monitoring Standards, New

Zealand

3 World Meteorological Organisation, Guide to Meteorological Instruments and Methods of

Observation. WMO-No 8; 7th Edition.

4 Department of Irrigation and Drainage - DID (2000). Volume 4 Hydrology and Water

Resource Urban Stormwater Management Manual for Malaysia. Department of Irrigation

and Drainage, Ministry of Agriculture, Malaysia.

5 Department of Irrigation and Drainage – DID (1984). WRP 14 Comparison of Raingauge

Performance Under Tropical Climate Conditions. Jabatan Pengairan dan Saliran,

Kementerian Pertanian Malaysia.

6 MetOffice UK- Rainfall Radar. https://www.metoffice.gov.uk/learning/making-a-

forecast/first-steps/making-observations/rainfall-radar

7 Water and Disaster Management Bureau, Ministry of Land, Infrastructure, Transport and

Tourism of Japan (2013) - Radar Observation of Precipitation for River Management in Japan

https://www.metoffice.gov.uk/learning/making-a-forecast/first-steps/making-observations/rainfall-radarhttps://www.metoffice.gov.uk/learning/making-a-forecast/first-steps/making-observations/rainfall-radar

Appendix A: Related Documents from MS ISO 9001: 2015

No. Title

A1 Borang Tatacara Kerja Ujijalan dan Penyelenggaraan Rainfall Tipping Bucket (TKUP 6)

A2 Borang Tatacara Kerja Ujijalan dan Penyelenggaraan Perakam Hujan (TKUP 7)

A3 Borang Tatacara Kerja Ujijalan dan Penyelenggaraan Telemetrik (TKUP 9)

A4 Borang Ujian dan Tentukuran Perakam Hujan (UT4)

Jenis Alat : Rainfall Tipping Bucket Tarikh Lawatan :Nombor Siri :Nama Stesen :Nombor Stesen :

Bil Tatacara Kerja Penyenggaraan Tindakan/CatatanAlatan Kerja i. Tool Box ii. Multimeter ii. Portable rainfall tipping bucket calibrator .

1 Periksa Casing Bersih / Kotor

2 Periksa Netting Ada / Tiada

3 Periksa spirit level Ada / Tiada

4 Periksa water reservoir Bersih / Kotor

5 Periksa bucket Bersih / Kotor

6 Periksa conductivity mercury Baik / Tidak Baik

switch / reed switch

7 Periksa conductivity Pulse cable Baik / Tidak Baik

8 Buat ujian tipping dengan mengunakan portable rainfall tipping bucket calibrator Jumlah Tips Tips( Range 40-42 Tip )

SAH SEHINGGA

: Disemak Oleh :

: Tarikh :

SEKSYEN PERALATAN HIDROLOGIBAHAGIAN PENGURUSAN SUMBER AIR DAN HIDROLOGI

JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

BORANG TATACARA KERJA UJIJALAN DAN PENYENGGARAAN RAINFALL TIPPING BUCKET ( TKUP 6 )

0.5 mm

Diperiksa Oleh

TKUP6_Issue03

Tarikh

A1-1

Jenis Alat : Nama Stesen :Nombor Siri : Nombor Stesen :Tarikh Lawatan :

Bil Tatacara Kerja Penyenggaraan

1 Tarikh dan waktu ON perakam / logger dahulu2 Tarikh dan waktu semasa sebenar 3 Tarikh dan waktu OFF perakam / logger 4 Bacaan perakam hujan / aras air mm / m

mm / m6 Bacaan telemetrik hujan / aras air mm / m7 Bacaan shaft encoder aras air m8 Bacaan tolok hujan / tolok lurus mm / m9 External Bateri Perakam hujan / aras air

i ) Bateri Perakam volts ( minima 11.0v ) Bateri ditukar : Ya / Tidakii ) Solar Panel volts ( minima 12.0v )

11 Bateri shaft encoder aras air : volts ( minima 11.0v ) Bateri ditukar : Ya / Tidak

12 Data Mini Loggeri ) Sambungan kabel ke sensor Baik / Tidak Baikii ) Bateri ( Min 3.0 volt ) __________ Voltiii ) Paparan Setting Baik / Tidak Baikiv ) Lampu LED Baik / Tidak Baikv ) Ujian penerimaan data menggunakan laptop atau PDA Baik / Tidak Baik

13 Periksa pelampung, pemberat, float cable,float pulley dan offset pulley perakam aras air : Baik / Tidak Baik Tindakan jika tidak baik

14 Kebersihan perakam : Bersih / Kotor

15 Rumah perakam : Baik / Tidak Baik Tindakan jika tidak baik :

16 Tempoh kehilangan data dan sebabnya :

SAH SEHINGGA

Diuji Oleh : Disemak Oleh :

Tarikh : Tarikh :

TKUP7_Issue03

DAN ARAS AIR ( TKUP 7 )

SEKSYEN PERALATAN HIDROLOGIBAHAGIAN PENGURUSAN SUMBER AIR DAN HIDROLOGI

JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

BORANG TATACARA KERJA UJIJALAN DAN PENYENGGARAAN PERAKAM HUJAN

A2-1

Tarikh Lawatan : Jenis Stesen : Hujan / Aras Air / Hujan & Aras AirNama Stesen : Pengenalan Stesen ( ID ) :Nama Sungai : Nombor Stesen :

: :

BilAlat kerja i. Tool Box ii.Multimeter iii. Meter Kuasa iv. Earth Tester v. Portable Tipping Bucket Calibrator

A RTU ( Remote Terminal Unit )

1. Jenis RTU 2. Nombor Siri 3. Casing RTU Baik / Tidak Baik4. Keypad/ Touch Skrin Baik / Tidak Baik5. Jenis Paparan LED / LCD Baik / Tidak Baik6. Paparan Tarikh Baik / Tidak Baik7. Paparan Masa Baik / Tidak Baik8. Paparan Hujan mm9. Paparan Aras Air Meter10. Stick Gauge Meter11. Connector dan kabel Baik / Tidak Baik

B Sistem Perhubungan

1. Jenis alat perbubungan ( VHF/GSM/PSTN/GPRS/MESH )2. Nombor Siri 3. TX Frequency mHz4. RX Frequency mHz5. Kuasa TX watts6. Kuasa RX watts7. Pengunaan arus sistem sedia amps8. Pengunaan arus sistem aktif amps9. Ujian suara Baik / Tidak Baik10. Jenis modem 11. Nombor Siri 12. Jenis antenna 13. Bilangan element 14. Jenis kabel 15. Connectors Baik / Tidak Baik16. Impedance antenna ohm17. Jenis tiang 18. Staywire Baik / Tidak Baik

TKUP9_Issue04

Tindakan/Catatan

Daerah / Kawasan Nama Stesen Repeater

Tatacara Kerja Penyenggaraan

SEKSYEN PERALATAN HIDROLOGIBAHAGIAN PENGURUSAN SUMBER AIR DAN HIDROLOGI

JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

BORANG TATACARA KERJA UJIJALAN DAN PENYENGGARAAN TELEMETRIK ( TKUP 9 )

A3-1

Bil Tatacara Kerja Penyenggaraan

C Sistem Bekalan Kuasa

1. Bekalan kuasa AC Ada / Tiada2. Jenis bateri 3. Bilangan 4. Voltan bateri volt5. Bilangan solar 6. Voltan solar volt7. Solar Charging amps8. Pendawaian Kemas/ Tidak

D Sistem Pembumian ( Earthing )

1. Impedance pembumian ohm2. Arrestor Ada/Tiada

E Sistem Penderia ( Sensor )

1. Jenis rainfall tipping bucket 2. Nombor Siri 3. Tamat tempoh 4. Ujian tipping ( 40-42 Tip )5. Jenis sensor aras air 6. Bacaan sensor aras air Meter7. Nombor Siri 8. Tamat tempoh9. Jenis perakam 10. Tamat tempoh 11.Jenis Encoder12. Bacaan Encoder Meter13. Bekalan kuasa encoder volt14. Stick Gauge meter

F Bangunan Stesen

1. Bagunan / Housing Baik / Tidak Baik2. Keselamatan stesen Baik / Tidak Baik3. Kebersihan stesen Bersih / Kotor

Diperiksa Oleh : Disemak Oleh :

: :

TKUP9_Issue04

Tindakan/Catatan

Tarikh Tarikh :

A3-2

Jenis Alat :Kapasiti Bucket : mmNombor Siri :Tarikh Ujian :

Bil Perkara Catatan

Perkara diuji dan diperiksa I. Komponen Mekanikal ii. Conductivity iii. Bucket capacity

1 Komponen Mekanikal 1.1 Casing Baik / Tidak Baik 1.2 Netting Baik / Tidak Baik 1.3 Spirit level Baik / Tidak Baik 1.4 Reservoir/Syphon Baik / Tidak Baik 1.5 Bucket Baik / Tidak Baik 1.6 Stopper screw Baik / Tidak Baik 1.7 Drain Hole Baik / Tidak Baik 1.8 Base Baik / Tidak Baik 1.9 Magnet Baik / Tidak Baik

2 Ujian Conductivity 2.1 Mercury switch/Reed Switch Baik / Tidak Baik

3 Ujian kapasiti bucket 3.1 Kapasiti bucket kanan ml ( Teori 15.69 ml ) 3.2 Kapasiti bucket kiri ml ( Teori 15.69 ml )

Bucket Tanpa Syphon 14.5ml - 15.0ml ( Amali )Bucket Dengan Syphon 14.4ml sahaja ( Amali )

Diuji Oleh : Disemak Oleh :

Tarikh : Tarikh :

UT4_issue03

SEKSYEN PERALATAN HIDROLOGI

JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

BORANG UJIAN RAINFALL TIPPING BUCKET ( UT 4 )