Effect of Changing Climate on the Water Resources of Upper Jhelum Basin (UJB), India

Abstract

Water resources originating from the alpine snow, glacier, recent precipitation and groundwater in the Kashmir Himalayas are important sources of fresh water to millions of people downstream. In the Upper Jhelum Basin (UJB) an increase in temperature has led to reduction in glacier cover and modification in the snowfall pattern (Jeelani et al., 2012; Lone et al., 2017) leading to the disturbance in timely availability of fresh water (Jeelani et al., 2012, 2013, 2017a). There is a lug in peak discharge from summer season to early spring season (Jeelani et al., 2017b, c), which can have strong bearing on the agriculture, horticulture and hydropower generation of the UJB, under prevailing climate change. It is, therefore, essential to comprehend the sources of water resources of UJB and to analyse and study the climate change impact on these resources. Climatic elements, such as precipitation, temperature, solar radiation, wind speed, humidity, etc. tend to have an effect on the direct input parameters for runoff, and alter it indirectly. For example, precipitation is received directly as a moisture input for runoff. Here, the form of input, e.g. rain or snow may generate different responses. Solar radiation, wind speed and temperature have an indirect relation with the runoff. Temperature increases the snow melting processes and thus would seem to enhance runoff; on the other hand, the evapotranspiration processes are also dependent upon the temperature of the region, which tends to retard the runoff volume. With respect to precipitation the intensity, duration and volume of a storm event affects the daily discharge and the peak flows (Subramanya, 2013). The stream flow in UJB show significant temporal and spatial variation exhibiting characteristic temporal/local variations, which may be dominantly due to snow melt, glacier melt, rainfall and base flow sources. Stable water isotopes (¹⁸O and ²H) are ideal tracers for estimating the sources of stream flow and other water resources of a region due to their conservative characteristics that is inherent to the water droplets (Gat, 1996; Clark and Fritz, 1997; Jeelani et al., 2013; Lone et al., 2019). The stable water isotopic values (δ¹⁸O and δ²H) of river and stream waters are often used to estimate the origin of water, through exploring the fraction among different reservoirs and evaporation processes (Dalai et al., 2002; Lambs et al., 2005; Bowen et al., 2011). In this study, we used natural tracers (δ¹⁸O and δ²H) of source waters of UJB to estimate their contribution and to assess the impact of climate change on the water resources of the basin.