Assessment of Water Availability in Major River Basins of Western Nepal
XIIIth World Water Congress, 1- 4 September, 2008, Montpellier, France ASSESSMENT OF WATER AVAILABILITY IN MAJOR RIVER BASINS OF WESTERN NEPAL. Mr. Jagat K. Bhusal, Senior Divisional Hydrologists, Department of Hydrology and Meteorology, Nepal Mr. Om Ratna Bajracharya Senior Divisional Hydrologists, Department of Hydrology and Meteorology, Nepal Mr. Lekh Nath Bagale, Hydrologist Engineer, Department of Hydrology and Meteorology, Nepal ABSTRACT Nepal gets about 80 % of annual rainfall during monsoon which lasts about 100 days only. Most rivers drain more than 75 % of the runoff during same period. In spite of limited arable land and poor irrigation facility, the backbone of Nepalese economy is still dependant on agriculture. Knowledge of the seasonal variability of rainfall and runoff plays a vital role in maximizing the yield. Integrated approach on utilizing the available water for irrigation development, hydropower generation, water supply and other uses are also other challenges in water resource management. This paper is based on study made by Nepal Irrigation Sector Project (NISP) on 77 basins of Western Nepal. Regional analyses were carried out. Long-term data of 35 basins were used to estimate the key hydrological parameters in the remaining 42 basins. Estimation on the natural flow, recurring floods and low flows, runoff- rainfall relationships, water balance, consumptive and non-consumptive water-use were made. Inter-basin groundwater flow is noticed in some areas. Hydropower development would be wise wise-uses of water resources in Nepal. Keywords: Western Nepal, Monsoon, Basins, Ground water. Rainfall, Runoff. INTRODUCTION River basins of Nepal Nepalese can be grouped broadly into (i) High Himalayan river basins, (ii) High mountain river basins (iii) Middle Mountain river basins (iv) Siwalik river basins and (v) Tarai river basins High Himal region have more snow and ice melt contribution where as High mountains and the Middle mountains find base flow sources with less frozen winter melt.
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