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You are here:  Home Services River Gauging

River Gauging

Following services are provided by the Hydrology Division for the Citizens, Entrepreneurs, Researchers and other organizations.

  1. Management of island wide hydro-meteorological observation network including adding or removing stations as per the requirements and priorities.
  2. Management of hydro-meteorological database and information system with necessary improvements to meet the present and future requirements of the country.
  3. Flood mapping including collection of required data and information related to major floods.

Hydrometric Network of Sri Lanka

There are 103 major river basins in Sri Lanka which cover the 90 % of total land extent of the country as shown in Fig. 1. The remaining 10% which is situated along the coast and Jaffna peninsula is covered by small watersheds which are not much important in hydrological aspect.

Figure 1: Hydrometric Network of Sri Lanka

About 24 major rivers (out of 103) convey the 80% of total flows generated within the Island and those are considered highly important in hydrological point of view. Our present hydrometric system is confined to those rivers. However there is a plan to expand and modernize the system in future under DSWRP (Dam Safety & Water Resources Planning Project).

The present hydrometric network of Hydrology Division comprises of 33 permanent stations and 40 peripheral stations covering 19 river basins. We are using manually operated instruments in all those stations except for few rain rainfall recorders and data loggers installed recently.

Thirty-three permanent stations, which record hourly water levels by the Department staff, are tabulated below (Table 1). Most of those stations are equipped with manual rain gauges which record rainfalls at 3 hr intervals.

River Basin Number, Name & Drainage area km2 Hydrometric Station Coordinates Period of Operation (from) Data Type
1 1. Kelani Ganga (2229) Nagalagam Street L/16(10.25*1.05) 1924 WL only
Hanwella L/12(10.65*6.55) 1973 WL, Q & RF
Glencourse L/8(4.15*2.2) 1948 WL, Q & RF
Holombuwa L/14(9.70*8.42) 1962 WL, Q & RF
Deraniyagala L/14(1.20*7.55) 1948 WL, Q & RF
Kithulgala L/9(6.3*3.3) 1948 WL, Q & RF
Norwood L/15(6.4*1.7) 1982 WL, Q & RF
2 3. Kalu Ganga (2719) Putupaula L/22(9.1*3) 1943 WL, Q & RF
Millakanda L/23(4.6*5.1) 1990 WL & Q
Ellegawa L/18(6*3.15) 1956 WL, Q & RF
Ratnapura L/24(5.5*8.15) 1995 WL, Q & RF
3 9. Ginganga (932) Baddegama O/13(3.5*0.15) 2006 WL, Q & RF
Tawalama O/9(0.65*2.75) 1973 WL, Q & RF
4 12. Nilwala Ganga (971) Panadugama O/19(10.75*3.56) 2011 WL & RF
Pitabeddara O/14(10.65*7.25) 1973 WL, Q & RF
Urawa O/15(3.5*4.2) 1994 WL & RF
5 22. Kirindi Oya (1178) Tanamalwila P/3(0.9*2.1) 1987 WL, Q & RF
Wellawaya M/17(13.5*1.6) 1956 WL, Q & RF
Kuda Oya P/3(0.75*6.35) 1989 WL, Q & RF
6 31. Kumbukkan Oya (1293) Nakkala M/13(12.55*5.35) 1973 WL, Q & RF
7 36. Heda Oya (611) Siyambalanduwa M/15(2.35*6.25) 1991 WL, Q & RF
8 54. Maduru Oya (1559) Padiyatalawa J/18(5.4*3.9) 1984 WL, Q & RF
9 60. Mahaweli Ganga (14448) Peradeniya I/25(4.95*4.25) 1943 WL, Q & RF
Taldena M/2(9.2*1.4) 1995 WL, Q & RF
Weragantota J/22(4.96*8.17) 1945 WL, Q & RF
Manampitiya G/22(11.5*5.11) 1953 WL, Q & RF
Nawalapitiya L/10(1.1*7.2) 1989 WL, Q & RF
10 67. Yan Oya (1538) Horowpathana D/21(11.1*6.65) 1951 WL, Q & RF
11 90. Malwathu Oya (3284) Tanthirimale - 2007 WL, RF
12 95. Mee Oya (1533) Galgamuwa F/18(9.2*0.25) 1987 WL, Q & RF
13 102. Maha Oya (1528) Badalgama I/22(3.85*7) 1953 WL, Q & RF
Giriulla I/22(13.13*8.7) 1962 WL, Q & RF
14 103. Aththanagalu Oya (736) Dunamale L/2(10.75*3.12) 2005 WL, Q & RF
Total 33

Table 1. Permanent Hydrometric Stations record hourly Water Levels and 3 hr Rainfalls

Eighteen rainfall stations are maintained by the department at the upper catchments crucial for monitoring floods (Table 2).

River Basin Number, Name & Drainage area km2 Rainfall Station Coordinates Period of operation (from)
1. Kelani Ganga (2229) Norton Bridge
Neluwaththuduwa 2008
3. Kalu Ganga (2719) Dolabodakanda 2007
Ketawala 2007
L/25(2.5*1.3) 2007
Tanjantenna 2009
Neelagama 2011
Duraikanda 2011
Amunutenna 2011
3. 12. Nilwala Ganga (971) Talgahagoda 2003
4. 31. Kumbukkan Oya (1293) Uwa-Karandagolla 2005
5. 99. Deduru Oya (2610) Wijaya Katupotha 1989
6. 54. Maduru Oya (1559) Akiriyankumbura 2007
7. 26. Menik ganga (1272) Buttala 2003
Kataragama 1990
Total 18

Table 2. Rainfall Stations maintained by Hydrology Division

Hydrology Division establishes temporary stations for Reservoir Panning and research works for the requirement of Irrigation Department and other Government Organizations on their request. Those stations are closed after the project period but records are available at the Hydrology Division for future uses.

Processed hydrological data and information are issued to outside agencies at standard rates approved by the Director General of Irrigation. Current rates are mentioned in Table 3.

Data /Information Type Rate
1 Daily average discharges (m3 / sec) Rs 2500 per year per station
2 Monthly stream flow in MCM Free of charge
3 Single Flood Event (WL & Q) Rs 300
4 Annual maximum / minimum values Rs 100 per year per station

Table 3. Standard Rates for issuing Data and Information

In addition to above, hourly water levels and discharges at principal stations are being processed now and will be made available in near future.

Summary of important data and information are included in the ‘Hydrological Annual’ the annual bulletin published by Hydrology Division which is distributed among related Government Organizations. Private organizations and individuals also can purchase a copy from Hydrology Division.

Last Updated on Thursday, 25 April 2013 05:05  

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