Understanding the influence of landcover on spring dynamics and evaporation, in Himalayan region, using stable isotope and discharge

The landuse landcover (LULC) patterns have potential control on recharge and discharge processes, dictating the hydrological behaviour, which is essential for informed decision-making in sustainable groundwater management at watershed levels. Stable isotopes (oxygen and hydrogen) can characterise various components of the hydrological cycle, including providing insights into the recharge and discharge dynamics of the mountainous springs. We collected high-frequency meteorological and hydrological (stream and springs) data and analysed their stable isotopic imprints in the Khulgad watershed of the central Himalayan region. Further, we examined the effect of LULC and topography on recharge and discharge dynamics of the springs. The altitude effect in rainfall isotopic composition was estimated to demarcate the potential spring recharge zones at the springshed level. The current observations were consistent with the global altitude effect, showing a decrease of -0.26 ‰ per 100 m of elevation gain. Moreover, the precipitation isotopes and spring water flux changes were determined by the Craig-Gordon model. The study found that springs located in barren land areas experience higher evaporation losses, than those in agricultural lands. These differences in stable isotope values in spring water highlight their usefulness in tracking how land use and environmental changes affect water movement in the Himalayan watersheds. By combining information on topography, geology, meteorological attributes, water flow, and isotopes, our study enhances understanding of the sensitivity of springs recharge and discharge processes to land use patterns. This research improves the current knowledge of spring water sustainability in mountain regions with bimodal precipitation sources.