Sustainable Management Of Bulbule Lake,Nepal:"Application Of Water Balance Approach"

Lakes are one of the highly visible features of landscape Nepal.They are pleasing aesthetically and important economically for recreation,water supply and as urban development is taking place at a fast pace,lake deterioration is quickly noticed and demand for remedial action are swift.Climate change is affecting the availability of water in many regions in terms of quantity and quality.Population growth and other demographic changes also play a vital role in reducing gap between supply and demand of water resources where demand overcomes supply at critical times of the year.Assessment of behavior of Bulbule Lake,located at Surkhet,Nepal,to the impact of climatic as well as non-climatic factors,is of utmost necessity as Lake Bulbule is utilized as a potential source of drinking water,irrigation and household purposes by the general public in the region.This lake also has a very high touristic value.In order to maintain its sustainability and cope with these aspects,a comprehensive and effective water management and planning strategy is required.For this,stakeholders will have to understand the hydrological behavior of lakes and its sensitivity towards climate change.The purpose of this study is to investigate water balance of the lake and identify causes for its fluctuation.Water balance is deemed necessary for managing demand and supply and also for strengthening integrated water management decision making by assessing and improving the validity of visions,scenarios and strategies.This study has been carried out accounting for meteorological and hydrological parameters,land use pattern,watershed characteristics,variation of these parameters over time and their effect on the lake water source.The methodology in this study will be to investigate the water balance of the lake using last 30 years precipitation data obtained from Department of Hydrology and Meteorology,Nepal.The lake water balance revealed the mean precipitation between the year 1986 and 2016 over the lake area to be 28245.15m~3 evaporation to be 16549.48m~3,inflow water through surface runoff as 132698.66m~3 and outflow from lake as 5725321.07m~3.The residual value of 5580926.74 m~3was obtained from the study,which can be concluded as the contribution of groundwater to the outflow.The result from this study showed that there is impact of climate change and land use on lake behavior.A general policy level plan and some low impact development techniques for control of runoff into the lake has also been proposed for the sustainable management of lake.Thus,this study can be used as a baseline for other lakes and their management.