Shallow aquifer groundwater dynamics due to land use/cover change in highly urbanized basin: The case of Kathmandu Valley

Abstract

Study regionKathmandu Valley, Nepal. Study focusIn the context of rapid urbanization in Kathmandu Valley (KV), this study quantifies spatial distribution of recharge and changes in drawdown under pumping rate and land use/cover change scenarios. Both scenarios are incorporated in a groundwater flow model in MODFLOW. New hydrological insights for this regionCurrent groundwater recharge rate is spatially distributed across the basin in a range of 95.3–85.3 % of precipitation in dry season and 48−38% of precipitation in wet season as per recharge area distributions. This results in groundwater recharge of 1.052 MCM and 1.949 MCM in dry and wet seasons respectively. In the case of increase in both pumping rate and encroachment of recharge areas (due to land use/cover change) and only encroachment of recharge areas, drawdown is projected to change respectively by −5.25 m in dry season and −7.39 m in wet season and −1.09 m in dry season and -3.63 m in wet season in 2050. The central urban, northern foothills, and southern parts are projected to observe more draw down. Meanwhile, the boundary forest area has the potential to increase the water table in the future.