Page - 594 - in Book of Full Papers - Symposium Hydro Engineering

COMMISSION INTERNATIONALE DES GRANDS BARRAGES ------- VINGT-SIXIÈME CONGRÈS DES GRANDS BARRAGES Autriche, juillet 2018 ------- STUDY ON SOIL EROSION OF MAHAWELI RIVER UPPER BASIN UNDER CLIMATE CHANGE USING SWAT MODEL   D. M. T. S. DISSANAYAKE Chief Engineer, IRRIGATION DEPARTMENT SRI LANKA 1. INTRODUCTION Reservoir sedimentation is a world-wide issue. The Mahaweli River Upper Basin (MRUB) in Sri Lanka consists of four major hydro reservoirs namely Kothmale, Victoria, Randenigala and Rantambe in a cascade system (Fig. 1). The total storage capacity of these reservoirs are 1,756.3 million m3 ,while total power generation potential is 582 MW equalling to 14.8% of installed total capacity of the country by 2014 [1]. The basin area above Victoria reservoir is considered for this soil erosion study. Selected basin area is of 1,865.52 km2 where 39.9% of it consists of slopes above 30%. Therefore, the potential for soil erosion is high which can be aggravated by high intensity rainfalls probably due to climate change. Eventually, this would cause sedimentation of reservoirs in the basin. Although, sedimentation cannot be completely avoided rate of sedimentation is very important as it is proportional to the decrease of active storage capacity of a reservoir. When hydropower reservoirs are concerned sedimentation will eventually lead to loss of energy production potential and for Sri Lanka this would be detrimental as the country heavily depends on hydropower. In addition, the reduction in reservoir capacity may create water scarcity for other users when the demand is high. Further, the loss in capacity of these    Étude sur l'érosion de la rivière Mahaweli bassin supérieur en vertu de changements climatiques à l'aide du modèle SWAT 594