Evaluation of Water Security in Kathmandu Valley before and after Water Transfer from another Basin

Abstract

Kathmandu Upatyaka Khanepani Limited (KUKL) has planned to harness water from outside the valley from Melamchi as an inter-basin project to supply water inside the ring road (core valley area) of the Kathmandu Valley (KV). The project, called the "Melamchi Water Supply Project (MWSP)", is expected to have its first phase completed by the end of September 2018 and its second phase completed by the end of 2023 to supply 170 MLD (million liters a day) through the first phase and an additional 340 MLD through the second phase. The area has recently faced a severe water deficit and KUKL's existing infrastructure has had a limited capability, supplying only 19% of the water that is demanded in its service areas during the dry season and 31% during the wet season. In this context, this study aims to assess the temporal trends and spatial distribution of household water security index (WSI), defined as a ratio of supply to demand for domestic water use for basic human water requirements (50 L per capita per day (lpcd)) and economic growth (135 lpcd) as demand in preand post-MWSP scenarios. For this purpose, data on water demand and supply with infrastructure were used to map the spatial distribution of WSI and per capita water supply using ArcMap. Results show a severe water insecurity condition in the year 2017 in all KUKL service areas (SAs), which is likely to improve after completion of the MWSP. It is likely that recent distribution network and strategies may lead to inequality in water distribution within the SAs. This can possibly be addressed by expanding existing distribution networks and redistributing potable water, which can serve an additional 1.21 million people in the area. Service providers may have to develop strategies to strengthen a set of measures including improving water supply infrastructures, optimizing water loss, harnessing additional water from hills, and managing water within and outside the KUKL SAs in the long run to cover the entire KV.

Implications of the Melamchi water supply project for the Kathmandu Valley groundwater system

“…The boundary of productive aquifer systems is outlined by the three KVWSMB groundwater districts with the new KUKL water supply service area located mostly in the central district ( Figure 1). The population in the valley has increased from 1.1 million in 1991 to 1.6 million in 2001 to 2.5 million in 2011 (CBS, 2003(CBS, , 2014a, which increased the water demand from 155 to 370 mld (Thapa et al, 2016a(Thapa et al, , 2016b(Thapa et al, , 2018. Agricultural lands in the valley have decreased from 62% to 42% between 198442% between and 200042% between (ICIMOD, 2007.…”

“…The KVWSMB groundwater districts are surrounded by low-permeability fractured rock formations and the outer periphery (hilly area) of the valley is covered by mixed forest. In the valley, the peri-urban area is partly agricultural and partly built up, while the central part of the valley is covered by built-up urban areas (Thapa et al, 2016a(Thapa et al, , 2016b(Thapa et al, , 2018. The northern groundwater district (NGD) is situated on top of coarse unconsolidated deposits, which have high permeability and the highest potential for groundwater abstraction (Figure 1).…”

“…The water deficit was estimated by Thapa et al (2016aThapa et al ( , 2016bThapa et al ( , 2018 for the entire service area using a constant demand of 135 liters per capita per day (lpcd) and future demand for projected population was estimated using collected population data of each sub-area (at ward level) within the service area (CBS, 2012) with predicted rates (CBS, 2014a). The estimated water deficit was considered for the groundwater abstraction scenarios.…”

“…The deficit between water demand and supply may increase up to 322 mld by 2021 (Udmale et al, 2016). The deficit is currently filled by other sources such as rainwater harvesting, stone spouts, springs, and pumping from privately owned wells (Thapa et al, 2016a(Thapa et al, , 2016b(Thapa et al, , 2018. Groundwater is considered to be a safe and reliable source of water, resulting in a steady increase in groundwater pumping from the valley's aquifers .…”

Socioeconomic Impacts of LCD-Treated Drinking Water Distribution in an Urban Community of the Kathmandu Valley, Nepal

“…The access to piped water had declined from 68% to 58% from 2003 to 2014 [11], and the Kathmandu Valley reported grossly inadequate and unreliable water supply services, where 4 million residents lived with 4.7% annual growth [12]. The Kathmandu Upatyaka Khanepani Limited has sole authority to distribute water in the urban areas of the Kathmandu Valley, but supplies only 19% of the total water demand during the dry season and 31% in the wet season in the service areas [13]. Aihara et al (2015) showed the daily averaged water collection from the piped water was 15.4 LPCD (liters per capita per day), as lowest as <4 h/week supply [14].…”