Impact of Climate Change on Gravity Flow Drinking Water Resource in the Upper Kosi Watershed, Lesser Himalaya

Abstract

In the age of climate change, the hydrological cycle is the most sensitive cycle which is being adversely affected. The natural water sources such as natural springs, rivulets, rivers etc of non-glacial fed watershed in Uttarakhand are drying and dying steadily disturbing society’s economy, and environment and creating threat on livelihood and ecosystem of the region. The basic goal of the current paper is to evaluate the impact of climate change on the gravity flow drinking water resource of the study area, Lesser Himalaya, Uttarakhand. For this objective, the hydrometeorological data is analyzed in this paper. The meteorological data, i.e., mean temperature (y = 0.059x + (-) 102.07) and average annual rainfall (y = 2.759x + (-) 4546.41) shows an increasing trend while the hydrological data shows a decreasing trend over the time. The study shows that in spite of an increasing trend in the annual rainfall pattern, the groundwater resource has been depleted significantly in the study area caused by change in rainfall rhythm which has disturbed the water recharging capacity of soil into the aquifers and the baseflow discharge of the gravity flow sources. Due to all these changes, the baseflow water discharge capacity of gravity flow sources have perturbed badly which is imposing threat on drinking water supply in the villages of the study area. At present, there are 93 gravity flow drinking water schemes in the study area. On an average, the baseflow water discharge of these schemes at their establishment year was recorded 40.11 l/m which has decreased to 23.46 l/m in 2018. Thus, on an average, about 16.65 l/m baseflow water discharge capacity of each scheme has been decreased since their establishment year. These data shows that how alarmingly the baseflow water discharge capacity at the sources of gravity flow schemes is depleting in the study area. Therefore, the study suggests a water source rejuvenation program for the sustenance of water sources, livelihood and ecosystem of the region.