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.

Groundwater storage changes in the Tibetan Plateau and adjacent areas revealed from GRACE satellite gravity data

“…A.2d) and Rajshahhi (Fig. A.2e), monthly SH GWS changes show agreement with those from well data (Mack et al, 2013;Gautam andPrajapati, 2014 andAbdullah Aziz et al, 2015). In addition, in the Upper Indus basin (Fig.…”

“…7 are induced by the excessive use of groundwater (Muradi et al, 2013;Mack et al, 2013;Gautam and Prajapati, 2014;Abdullah Aziz et al, 2015;Correspondent, 2015;Ahmad, 2011;Hoque et al, 2007 andSiebert et al, 2013).…”

Subsidence in the Kathmandu Basin, before and after the 2015 Mw 7.8 Gorkha Earthquake, Nepal Revealed from Small Baseline Subset-DInSAR Analysis

“…The Kathmandu Basin extends for about 30 km in an east-west direction and 25 km in a north-south direction with an average surface elevation of about 1340 m above mean sea level. The basin is a densely populated area in Nepal with a population of 2,517,023 in 2011 (Gautam and N Prajapati 2014). The basin is surrounded by the sedimentary Phulchauki and Chandragiri mountain ranges to the south and west, and the metamorphic Shivapuri range to the north and east (Yonechi 1973).…”

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

“…For example, the KUKL (previously Nepal Water Supply Corporation) increased groundwater pumping from 2.3 mld in 1979 to 29.2 mld in 1999 (Pandey et al, 2012) and the total estimated pumping including private withdrawals was 59.1 mld in 1998 (Metcalf & Eddy, 2000). In 2009, the estimated groundwater withdrawals reached 70.9 mld (Dhakal, 2010), resulting in a rapid decline of groundwater levels across the valley from 2.57 m to 21.58 m between 200321.58 m between and 201421.58 m between (KVWSMB, 2012Shrestha, 2012;Gautam & Prajapati, 2014) below ground surface. Rapid urbanization may have exacerbated the decline by increasing impermeable surfaces in the valley's groundwater recharge areas (Cresswell et al, 2001) and have increased the vulnerability of the aquifer system to pollution due to inadequate treatment of wastewater from urban areas Shrestha et al, 2016;Gautam et al, 2017).…”