Abstract：
A reliable water supply in different Himalayan River basins is increasingly important for domestic, agriculture, and hydropower generation. These water resources are under serious threat due to climate change, with the potential to alter the economic stability of 237 million people living in the Indus River Basin alone. In the present study, we used new stable water isotope data set to identify and estimate the different sources of streamflow and their controlling factors in the Upper Indus River Basin (UIRB), India. The data set presented wide spatial and temporal variability without the distinct isotopic signature of various sources of river flow. However, variable but distinct signatures of sources of river/stream flow exist at the sub-basin or catchment scale. These variabilities are ascribed to changing physiographical, meteorological, and local climatic conditions. Further, the distinct microclimatic conditions including altitudinal variability, aspect slope, etc. govern the spatio-temporal variability of sources and streamflow, hence different lapse rates at sub-basin/catchment scale. The study suggested that the contribution of snowmelt and glacier melt to river flow varies spatially and temporally. The Bayesian mixing model results suggested that snowmelt contribution is higher in Indus (63 ± 1.2%) and Shyok (58 ± 1.7%) while as, glacier melt contribution is higher in Nubra 64 ± 2.3% and Suru 60 ± 2.7% sub-basins/catchments. The groundwater contribution (baseflow) sustains and regulates the flow in rivers/streams during winter and spring, which is very vital for the local water supply. The study suggests that the spatially diverse rugged topography and microclimate in UIRB dominantly control the differential contribution from various sources of river flow. The warming climate, which has resulted in a decrease in solid precipitation, continuous glacier mass loss, early melting of snow cover, etc., would have an inconsistent impact on the perennial flow of rivers with the potential to alter the economic and political stability in the region.
摘要：
喜马拉雅河不同流域的可靠供水对家庭越来越重要，农业,和水力发电。由于气候变化，这些水资源受到严重威胁，有可能改变仅生活在印度河流域的2.37亿人的经济稳定。在本研究中,我们使用新的稳定水同位素数据集来识别和估计上印度河流域（UIRB）的不同流量来源及其控制因素，印度。数据集呈现广泛的时空变化，而没有各种河流来源的独特同位素特征。然而,子流域或流域尺度上存在可变但不同的河流/溪流来源特征。这些变化归因于不断变化的体貌学，气象,和当地的气候条件。Further,独特的微气候条件，包括海拔变化，纵横坡度,等。控制源和水流的时空变化，因此，子流域/流域尺度的失效率不同。研究表明，融雪和冰川融化对河流流量的贡献在空间和时间上都有所不同。贝叶斯混合模型结果表明，印度河（63±1.2％）和Shyok（58±1.7％）的融雪贡献较高，而在Nubra64±2.3％和Suru60±2.7％的子盆地/集水区，冰川融化的贡献更高。地下水贡献（基流）在冬季和春季维持和调节河流/溪流的流量，这对当地的供水非常重要。研究表明，UIRB中空间上不同的崎岖地形和小气候主要控制着各种河流来源的不同贡献。气候变暖,这导致了固体沉淀的减少，连续的冰川质量损失，早期积雪融化，等。,将对河流的常年流量产生不一致的影响，有可能改变该地区的经济和政治稳定。
