Springs of Pasighat, a valuable resource for the community: A hydrogeological study carried out using geoelectrical resistivity technique

Abstract

Many springs occur in and around Pasighat. Eight major springs of the area were considered for the study. These springs are Dimple type, Fault dam type, and a combination of Fault dam and Border type. The highest discharge is 263.23 L/sec and the lowest is 1.91 L/sec. The aquifers are terrace deposits that comprise of unsorted boulders, cobbles and pebbles in sandy matrix and the springs occur at the base of different terrace levels. Due to the scarcity of dug wells or deep tube wells, subsurface investigations were done using vertical electric sounding (VES). VES data generated at six locations show H-type situation. The aquifers are at shallow depth, unconfined, and have good hydrogeological prospects. At the T2 terrace, volume of water stored is 42,14,512.5 m3 and the combined discharge of springs is 38,257.92 m3/day. These springs are recharged by precipitation and influent streams. Springs of the study area are aligned along the Himalayan Frontal Thrust (HFT) and its splays, and they have a major role in the evolution of these springs. The springs were formed due to topographic breaks and less permeable collapsed debris. Local people use spring water for the household, irrigation, laundry, and fisheries.