Melamchi water supply project: potential to replenish Kathmandu’s groundwater status for dry season access Pennan Chinnasamy a,b, * and Surendra Raj Shrestha c a Indian Institute of Technology, Bombay, Mumbai, Maharashtra, India *Corresponding author. E-mail: p.chinnasamy@iitb.ac.in b International Water Management Institute, Sanepa, Lalitpur, Nepal c Ground Water Resources Development Board (GWRDB), Ministry of Irrigation, Government of Nepal, Babarmahal, Kathmandu, Nepal Abstract Kathmandu Upatyaka Khanepani Limited (KUKL) currently uses 35 surface and 57 groundwater sources to supply water for Nepal’s capital, Kathmandu. It is necessary to understand if the Melamchi Water Supply Project (MWSP) can assist lean period water supply by indirectly increasing groundwater storage, through diverting excess water supply to groundwater recharge zones. The current study analyzed long-term groundwater depletion to assess available groundwater storage, followed by assessment of groundwater balance for the Kathmandu Valley. Results show that total groundwater extraction for Kathmandu was 69.44 million cubic meters (MCM) and drawdown of the groundwater surface was 15–20 m since the construction of wells in 1984/85, indicating sub- stantial overexploitation. Results indicate that the ongoing unmet demand of 170 MCM/year can be easily satisfied if groundwater storage is recharged effectively, as underground water storage potential is 246 MCM/year due to a groundwater depletion rate of 2–10 m. From results, it is evident that that the timely implementation of the MWSP can help ease ongoing water stress and aid in reversing the damage caused to groundwater storage. In the long run, MWSP can supply water and recharge groundwater during monsoon periods, thus improving the quality of life and socio-economic status in Kathmandu. Keywords: Groundwater; Kathmandu; Melamchi Water Supply Project; Nepal; Water supply Introduction Nepal is one of the fastest urbanizing countries of South Asia, with Kathmandu, the capital city, having the highest urbanization rate in the nation ( Jha & Shrestha, 2010). As a result, the city faces water management issues in supplying for the water demands of the growing city (Lacombe et al., 2019). Kathmandu houses the largest population (approximately 1.5 million) and economy of Nepal Water Policy 21 (2019) 29–49 doi: 10.2166/wp.2019.080 © IWA Publishing 2019 Downloaded from http://iwaponline.com/wp/article-pdf/21/S1/29/632485/021000029.pdf by guest on 14 June 2022