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.

The main water supply pipeline of the Lalitpur District passes through the Bungmati Landslide, which occurs on soft fluvio-lacustrine sediments of the Kathmandu Valley. The landslide study was carried out during the two rainy seasons (i.e. in 1992 and 1993). In the landslide zone, the Lukundol Formation is overlain by the Chapagaon Formation. The Lukundol Formation includes beds of peat, clayey diatomite, and fine sand, whereas the Chapagaon Formation consists mainly of gravel and sand. The detailed study of the landslide included engineering geological mapping, soil test, Rod Driving Test, and measurement of the displacement by the Vertical Wire Extensometer. The depth and total displacement of the slip surface were 6-7 m and 5- 25 cm, respectively. The main cause of sliding was the compositional difference between the Lukundol Formation and Chapagaon Formation. Percolation of water through the gravel beds resulted in the formation of pore water pressure and the development of the slip surface along the contact of the Lukundol Formation.

Groundwater has been tapped in the Kathmandu valley since ancient times through the traditional stone-carved water-spouts called Dhunge Dharas and dug wells. Present study deals with hydrogeological situation of dug wells and Dhunge Dharas. Quality of groundwater is evaluated on the basis of pH versus topography. The Dharas are classified into natural types on slopes and artificial ones in the valley poor. Depth of water table is observed to be between nearly at ground surface to 6m below the sloping ground and exceptionally up to 12.25m below ground level (bg l) on the terraces. Chemical quality of groundwater is found to be good except at a few places.