Rapid socio-economic development has precipitated substantial transformations in land use and land cover (LUCC) within the Yanhe River basin, significantly impacting production dynamics, confluence mechanisms, and the basin's runoff response processes. To elucidate the runoff response patterns under varying land use/land cover change conditions, this study analyzed the land use change characteristics from 1980 to 2020. Employed the SWAT (Soil and Water Assessment Tool) model, and simulated the precipitation-runoff dynamics under five distinct land use scenarios to scrutinize the basin's runoff response to varying land use conditions. The results demonstrated the applicability of the SWAT model to the Yanhe River basin, with R-2 and Ens values for monthly runoff at two hydrological stations exceeding 0.6 during both calibration and validation periods. Between 1980 and 2020, the area of farmland decreased by 27.96%, whereas the areas of woodland and grassland by 36.59% and 16.2%, respectively. Scenario analysis revealed that the primary contributors to the increased runoff in the study area, in descending order, were grassland, farmland, and woodland. The results indicated that converting farmland to woodland would reduce the runoff depth by 0.26 mm, while converting farmland to grassland would increase the runoff depth by 0.39 mm in the watershed. The conversions exhibited pronounced seasonal effects, with varying degrees of runoff depth changes observed across different seasons. The contribution order of different hydrological years to runoff depth change rates was median flow year > low flow year > high flow year. Land use conversion, particularly among farmland, grassland, and woodland, exerts diversified impacts on runoff depth across different water periods.

To assess the change of glacier mass balance (GMB) in the Poiqu/Bhotekoshi basin in the context of global warming, this study applied a conceptual Hydrologiska Bryans Vattenbalansavdelning (HBV) hydrological model to quantify the GMB in the area. The HBV model was trained and validated based on in-situ hydro meteorological data from 10 weather stations in the basin. The dataset, which consists of the daily observations for both rainfall and air temperature, was partitioned into two decades, 1988-1998 and 1999-2008 for calibration and validation, respectively. The calibrated model was adopted to restore the daily runoff depth and then estimate the annual changes of GMB in Poiqu/Bhotekoshi basin over the period of 1988-2008. Results show that the Nash-Sutcliffe efficiency coefficient (R-eff) of the daily runoff depth simulation after the runoff calibration process was above 0.802. Therefore, the simulated values of the HBV model are reliable and can be used to estimate the GMB of Himalayan cross-border glacial mountain basins with huge elevation difference, and provide scientific data support for water resources management. Furthermore, the result demonstrated a slow year-by-year rise of snow water equivalent because of global warming, and it highly correlates with the soil moisture, the spring temperature and the summer precipitation.