Drawdown and Dynamics of Groundwater Table in Kathmandu Valley, Nepal

ABSTRACT

Groundwater resources in Kathmandu valley provide water for human consumption, industry, hotels and agriculture as well. Rapid urbanization, mushroomed increment in the built up area, overexploitation of surface and groundwater resource, removal of vegetation cover, change in land use pattern, and formation of impervious surface have led the ultimate lowering of groundwater table and minimization of groundwater recharge as well. This study quantifies the drawdown rate along with the groundwater dynamics across the Kathmandu valley, as the valley constitutes mostly of the urban population of Nepal including the capital city. In Kathmandu valley, for domestic purpose as well as the industrial purpose, water has been pumped continuously surpassing the natural recharge. The groundwater table drawdown has been estimated based on the recorded data of average static groundwater table depth and was found to be 0.7249 m in average and linear regression model of drawdown has been depicted along with the associated range of standard deviation. This drawdown has close proximity with the Mexico City alluvial deposit where ground subsidence is nowadays noticeably occurring. Similar land subsidence, water pollution and scarcity of water would be the near future consequence in Kathmandu valley as nearly 50 % of valley population relies on groundwater resources. Similarly, the groundwater dynamics study has shown the shifting of drainage towards southwestern part of Kathmandu valley. Thus Kathmandu valley is in dire need of proper groundwater management execution in order to avoid the hydrological, hydro-geological and environmental impacts of rapid drawdown.

Keywords:

Draw down rate, dynamics of flow, groundwater table, Kathmandu valley, overexploitation, urbanization.