Quality of Irrigation Water in Sri Lanka Status and Trends
Already available and newly collected data sets on water chemistry of twenty reservoirs located in seven river basins in Sri Lanka were analyzed to determine the status and trends in irrigation related water quality characteristics. pH of irrigation water varied within a wide range but the upper limit did not exceed the proposed level suitable for irrigation water. Salinity was found beyond the threshold level (1.250 g l 1 ) only in two reservoirs located downstream of the Malwathu Oya basin and the electrical conductivity had never reached above 1 mS cm 1 . Sodium absorption ratio (SAR) was well below the threshold value of 6 meq l 1 in the study reservoirs. Least square regression model showed that electrical conductivity was a good predictor of salinity and SAR. Time series data showed no marked changes in irrigation water quality of the reservoirs located in the Mahaweli river basin over the last forty three years with respect to EC levels but the EC of those proximate reservoirs receiving additional transfer water from the trunk stream of the Mahaweli river showed a progressive decrease following the trans basin diversion.
Amarasinghe, U.S., Costa, H.H. and M.J.S. Wijeyaratne (1983). Limnological and fish production potential of some reservoirs in Anuradhapura District. Sri Lanka Journal of Inland Fisheries, 2: 14-29.
Amarasiri, S.L. (1973). Water Quality of Major Irrigation Tanks in Sri Lanka. Trop. Agri., CXXIX: 19-25.
APHA (1989). Standard Methods for Estimation of Water and Waste Water. 17th Edition. American Public Health Association, Washington DC.
Ayers, R.S and D.W. Westcot (1989). Water Quality for Agriculture. Food and Agriculture Organization of the United Nations, Rome. 174 pp.
Chandrasoma, J., Muthukumarana, G., Pushpakumara, K. and A. Sreenivasan (1986). Limnology and fish production in Udawalawe reservoir. Journal of Inland Fisheries, Sri Lanka, 3: 68-88.
Douglas, I. (1968). The effects of precipitation chemistry and catchment area lithology on the quality of river water in selected catchments in Eastern Australia. Earth Science Journal, 2: 126-144.
Dissanayake, C.B., Weerasooriya, S.V.R. and S.H.G. de Silva (1982). The environmental chemistry of Mahaweli River. Sri Lanka Int. J. Env. Studies, 78: 207-293.
Gibbs, R.J. (1970). Mechanism controlling world water chemistry. Science, 170: 1088-1090.
Gower, A.M. (Ed.) (1980). Water quality in catchment ecosystems. John Wiley & Sons, Chichester. 335 pp.
Gunawardena, H.D. and A.M.K.R. Adhikari (1981). Studies on the quality of irrigation waters in Kalawewa area. J. Nat. Sci. Con. Sri Lanka, 9: 121-148.
IMII (1995). Kirindi Oya Irrigation and Settlement Project. Impact Evaluation Study. Vol 11 Annexes (Final Report). International Irrigation Management Institute, Colombo, Sri Lanka.
Madduma Bandara, C.M. (2000). Status of Water Resource Research in Sri Lanka and their Potential for Further Study xxxvii-xli pp, Status and Further Directions of Water Research in Sri Lanka. Proceedings of the National Conference held at BMICH, Colombo, Sri Lanka, Nov. 4-6, 1998.
Matsuno, Y., Alkaduwa, W.K.B. and Y. Shinogi (2000). Irrigation water quality in the southwestern Dry Zone of Sri Lanka. In: M. Samadm, N.T.S. Wijesinghe and A. Birech (eds.), 89-100 pp. Status and Further Directions of Water Research in Sri Lanka. Proceedings of the National Conference held at BMICH, Colombo, Sri Lanka, Nov. 4-6, 1998.
Nissanka, C. (2002). Empirical models for fish yield prediction in selected reservoirs in the dry zone of Sri Lanka. Ph.D. Thesis, University of Kelaniya. 256 p.
Roonage, M.A., Amarasinghe, P.S and S.D.S. Yapa (1995). Effect of Water Quality and Soil Salinity on Paddy Cultivation under different drainage conditions in Kirindi Oya, Irrigation Project. Agri. Eng., 7(1).
Rhoades, J.D. (1990). Assessing suitability of water quality for irrigation. In: Kandiah, A. (ed) 52-70 pp. Water, Soil and Crop Management relating to the Use of Saline Water. Food and Agriculture Organization of the United Nations, Rome.
Schiemer, F. (ed) (1983). Limnology Parakrama Samudra Sri Lanka: A case study of an ancient man-made lake in the tropics. Development in Hydrology. Dr. W. Junk Publishers, The Hague, the Netherlands.
Silva, E.I.L. (1996). Water Quality of Sri Lanka. A review of twelve water bodies. IFS, Kandy Sri Lanka. 141 p.
Silva, E.I.L. (1998). Rain water quality and buffer intensities of surface water quality in Sri Lanka. In: Proceedings of the multi-disciplinary symposium on rainwater harvesting for water security. Colombo, Sri Lanka, 35-38.
Silva, E.I.L (1999). Status of surface water quality in Sri Lanka. SCOPE, 82: 111-124.
Silva, E.I.L. and R.W. Davies (1986). Primary productivity and related parameters in three different types of inland waters in Sri Lanka. Hydrobiologia, 37: 239-249.
Silva, E.I.L. and R.W. Davies (1987). The seasonality of monsoonal primary productivity in Sri Lanka. Hydrobiologia, 150: 165-175.
Silva, E.I.L and M.J.S. Wijeyaratne (1999). The Occurrence of Cyanobacteria in the Reservoir of the Mahaweli River Basin in Sri Lanka. Sri Lanka J. Aquat. Sci., 4: 51-60.
Silva, E.I.L. and G.A.R.K. Gamlath (2000). Catchment characteristics and water quality of Three Reservoirs (Victoria, Minneriya and Udawalawe) in Sri Lanka. Sri Lanka J. Aquat. Sci., 5: 55-73.
Silva, E.I.L. and F. Schiemer (2001). Human Factor: Fourth Dimension of Limnology in the Tropics. In: S.S. De Silva (ed). Proceedings of International Workshop on Reservoir and Culture-Based Fisheries: Biology and Management. ACAIR Proceedings, 98: 215-226.
Silva, E.I.L., Amarasinghe, U.S., Silva, S.S. De, Nissanka, C. and F. Schiemer (2002). Some aspects of photosynthetic characteristics in a set of perennial irrigation reservoirs located in five river basins in Sri Lanka. Hydrobiologia, 485: 19-33.
Shortt, R.L. (2001). Water quality and health: Implications for irrigation management in Southern Sri Lanka. M.Sc. Thesis, McGill University.
State of the Environment (SOE), Sri Lanka. 2001. United Nation Environment Programme, Regional Resource Center for Asia and Pacific (UNEP-RC.AP), AIT, Thailand, 106 p.
TAMS (1980). Environmental Assessment: Accelerated Mahaweli Development Programme. Vol. III: Aquatic Environment H: 2-8.
Vitousek, P.M. (1977). The regulation of element concentration in mountain streams in the northeastern United States. Ecological Monographs, 47: 65-87.
US Operation Mission (1961). Mahaweli Ganga Trans basin Diversion Scheme. Vol III: Reconnaissance Land Classification and Soil Survey Report. Irrigation Department, Colombo.
Webb, B.W. and D.E. Walling (1974). Local variation in a background water quality. Science of the Total Environment, 3: 141-153.