ADB IHE Delft Knowledge Partnership
Asian Development Bank - IHE Delft

Groundwater study for Drinking Water Supply Kathmandu

In November 2012, IHE Delft, together with a Japanese geologist and a hydrogeologist from Tribuvan University, Kathmandu, Nepal, started an exploratory study on the potential for sustainable groundwater development in the south western part of Kathmandu Valley.

Final aim of developing groundwater in this part of Kathmandu Basin is to reduce withdrawals from existing water supply schemes on the Bagmati upstream of Kathmandu City via a trading approach with the Kathmandu Valley Water Supply Management Board. Reduction of withdrawals upstream will assist in restoring natural flow conditions of the Bagmati river, which runs through Kathmandu. This river is heavily polluted due to uncontrolled waste water discharging from Kathmandu into the river. One of the reasons for the heavy pollution is that flow of the river has almost completely ceased to exist, especially during the dry season. The idea is that reduction of upstream withdrawals via trading with downstream groundwater abstraction will assist in restoring natural flow conditions, and, in turn, this will assist in reducing current levels of pollution in the Bagmati river.

After carrying out a combined geological and hydrogeological fieldwork in the entire south western Kathmandu valley, the team identified a number of potential groundwater sources. One of those sources is an aquifer in the Pharping area. In this area, Kathmandu Upatyaka Khanepani Limited (KUKL), the public supply drinking water company, already operates two wells during the dry season, but the extent of the aquifer KUKL is abstracting from is unknown.

After carrying out a geophysical study, a number of sites were identified for exploratory drilling. First results indicated that the aquifer does not extent too far south of existing facilities. Further work will identify the aquifer's potential northward of current KUKL abstractions wells. 

Work on identifying the potential of this aquifer and other potential groundwater sources will continue. Then, a water supply engineer will prepare a preliminary water supply design and construction, including a cost estimate. This will feed into the conceptual master plan and phase-2 implementation plan of the Bagmati River Basin Improvement Project (BRBIP), which will be carried out with support of ADB in the coming years in Nepal.