Monday, April 12, 2010: 1:30 p.m.
Lawrence A/B (Westin Tabor Center, Denver)
Groundwater is a major source of water supply in Kathmandu Valley, the capital city of Nepal. Since mid-1980s, when groundwater extraction from the valley’s aquifers (shallow and deep aquifers separated vertically by an aquitard layer) exceeded recharge, the gap between extraction and recharge is continuously widening; however, management interventions are yet to be imposed. Any management decisions would be based on detail understanding of hydrogeological characteristics and storage capacity of the aquifers, groundwater flow characteristics, etc. Few earlier studies suggest northern part of the groundwater basin has high percentage of aquifer units. However, spatial distribution of aquifer volume and corresponding groundwater storage potential are yet to be estimated. This study, thus, aims to provide an acceptable estimate of groundwater storage distribution in the Kathmandu Valley’s aquifers. The methodology consists of collecting highly scattered hydrogeological and lithological datasets from a large number of sources; estimating aquifer geometry based on borehole lithology and available knowledge in the published literatures; and finally estimating spatial distribution of aquifer volume and corresponding groundwater storage potential in shallow and deep aquifers based on hydrogeological information and aquifer thickness using GIS technique. Results show that shallow and deep aquifers can store 1,452.25 MCM (range: 0 to 6,829.8 m3) and 572.21 MCM (range: 6.9 to 5,233.5 m3) groundwater respectively, at maximum. Assuming future extraction level same as in 2001, i.e. 21.56 MCM/year, the total storage in the valley’s aquifers can fulfill groundwater demand for the next 93.9 years. Spatial distribution of storage potential shows the prospects of favorable areas for groundwater development. Such results are useful in developing groundwater management plans.