RETRIEVING GROUNDWATER DEPLETION AND DROUGHT IN WESTERN NEPAL

Western Nepal is experiencing increasing temperature and decreasing precipitation trends, making the region highly susceptible to droughts. Detailed study on characterizing drought and its implications on groundwater is necessary to evaluate drought severity and management planning. Therefore, the overall objective of this study is to address both the characteristics of occurrence of drought, as well as the groundwater response to drought. The liquid water equivalent thickness (LWET) or the total water storage (TWS) inferred from GRACE satellite observations were used to estimate the monthly groundwater storage change over the period 2002-2016 and Standardized Precipitation Index derived from observed precipitation data were used to evaluate the characteristics of drought. Analysis indicates a notable reduction in groundwater storage over the past decade. By the means of the inter-comparisons with drought year and GRACE LWET anomaly, this was clearly inferred groundwater depletion is associated with the drought phenomenon in western Nepal. Analysis reveals the larger LWET deficits due to drought in 2005, 2006, 2007, 2009, 2012, 2013, 2014 and 2016. During the widespread drought of years 2005, 2006, 2012 and 2016 ,there is significant reduction in groundwater storage and very low recharge in monsoon season. Since 2016 has the most widespread drought in the region, the LWET has plummeted in 2016. LWET deficits covered all area of western Nepal.