Estimation of Groundwater Resources in Kathmandu Valley, Nepal

Abstract

The fluvio lacustrine deposits of the Kathmandu Valley, Nepal are divided into four zones in terms of aquifer distribution. Deep confined aquifer in the south, GRI, medium depth interbedded aquifer, GRIT, shallow unconfined aquifer in the north, GRIII and an unconfined aquifer of thin sand and gravel deposit widely distributed on the surfaces of the terraces and other locations. Surface sediment deposits of fine to medium grain size referred to as surface gravel deposits, supply considerable quantity of water for residents of the valley through "Dharas" (stone spouts) and wells at superficial depths. The discharge is reported to double during monsoon period. General quality of water from these sources is considered good with some exceptions. For some years now, underground water source is believed to contribute about 40% of the city water supply. This is aggregated even further by pumping of the water in the private household with overdrafting going on for sometime. This overdrafting can be observed from the declining trend of the water levels in the tube wells. The total dynamic reserve of the valley is 12,730 m3/day. The average amount of infiltration from the rainfall is 17.2%. The discharge from "Dharas" adds to 1380 m3/day. Hence if the ground water is properly managed, overdrafting may not be necessary. Multipurpose projects specially in the northern zone should help induce artificial recharge. Otherwise, Kathmandu may face a potential disaster in the near future.

Variations of the Physicochemical Parameters and Metal Levels and Their Risk Assessment in Urbanized Bagmati River, Kathmandu, Nepal

“…The basin filled sediments are mainly loam and composed of unconsolidated clay, silt, sand, and gravels. The headwaters of Bagmati river contain mica gneiss and biotite schist with muscovite, whereas the southern part of the river consists of thick clay formation and basal gravel [28] and the bed rock downstream contains fine grained phyllite, quartz containing argillaceous limestone, slates, shales, claystones, and mudstones [29,30]. In this study we consider samples from 5 major tributaries (Manahara, Dhobi, Tukucha, Bishnumati, and Balkhu Khola) and some minor tributaries (Mahadev Khola, Hanumante, and Godavari).…”

The SAFER geodatabase for the Kathmandu valley: Bayesian kriging for data-scarce regions

“…The V S30 map is shown in Figure 2a. The map describes well the general distribution of the metamorphic bedrock surrounding the valley and characterizes the inner distribution of valley sediments of lacustrine and fluvio-deltaic origins (Shrestha et al, 1998). Further information on the geotechnical parameters associated with these soils are provided in Gilder et al (2020).…”

“…The first map, originally developed by Yoshida and Igarashi (1984), provides information on the geology inferred from geomorphology (Figure 11a and b). The second map, developed by Shrestha et al (1998), provides geological information as a result of engineering soil classification (Figure 11c and d). Figure 11a shows how the interpolated results (i.e.…”

Assessment of Arsenic Contamination in Deep Groundwater Resources of the Kathmandu Valley, Nepal

“…The limestone dominates to the south, whereas to the east and west, the valley is bordered by phyllites and siltstones. Granite gneisses thrust into the rocks of the Kathmandu Complex that form the northern border of the valley [22].…”