Description: Understanding runoff generation and dynamics is the basis for water resource management, while water isotopic ratios are a potential tool for studying the mechanism on a large scale. In this paper, spatial variations of δ18O and δD of river water and their sources within a large region of the Tarim River were investigated. The results showed obvious spatial variations of both water isotope values along the river flow direction, and significant seasonal variation occurred within the river water isotopes. This indicated that different proportions of rain and melt water entering river water should lead to spatial variation, and for mid-stream and downstream regions, the transformation relationship between surface water and groundwater should consider less input of melt water. Furthermore, we quantitatively determine the ratio of different water sources using the stable isotope mass balance method and other stable tracer elements. Results showed the contribution of ice-snowmelt water varied from 14.97% to 40.85%, that of rain varied from 9.04% to 54.80%, and that of groundwater varied from 15.34% to 58.85%, and they also showed that baseflow is a factor connecting melt water and groundwater, which meant the Hotan River and the Yarkand River are melt water–dependent rivers, and seasonal precipitation is the main water supply source of baseflow in the Aksu River and the Kaidu River.

Description: Water, Vol. 10, Pages 468: Estimation of the Source Apportionment of Phosphorus and Its Responses to Future Climate Changes Using Multi-Model Applications Water doi: 10.3390/w10040468 Authors: Jian Sha Zhong-Liang Wang Rui Lu Yue Zhao Xue Li Yun-Tao Shang The eutrophication issue in the Yangtze Basin was considered, and the phosphorus loads from its tributary, the Modaoxi River, were estimated. The phosphorus flux and source apportionment of the Modaoxi River watershed were modeled and quantified, and their changes with respect to future projected climate scenarios were simulated with multiple model applications. The Regional Nutrient Management (ReNuMa) model based on Generalized Watershed Loading Functions (GWLF) was employed as a tool to model the hydrochemical processes of the watershed and thereby estimate the monthly streamflow and the phosphorus flux as well as its source apportionment. The Long Ashton Research Station Weather Generator (LARS-WG) was used to predict future daily weather data through the statistical downscaling of the general circulation model (GCM) outputs based on projected climate scenarios. The synthetic time series of daily precipitation and temperatures generated by LARS-WG were further used as input data for ReNuMa to estimate the responses of the watershed hydrochemical processes to future changed climate conditions. The results showed that both models could be successfully applied and that the future wetter and warmer climate trends would have generally positive impacts on the watershed phosphorus yields, with greater contributions coming from runoff. These results could provide valuable support for local water environmental management.