Analysis of changes and attribution of inflow runoff in Xidayang reservoir

Based on hydrological and meteorological data from the upstream basin of the Xidayang Reservoir from 1980 to 2022, several methods were employed to analyze the trends and abrupt changes in inflow runoff. These methods include linear regression, a 5-year moving average, cumulative anomaly analysis, the Mann-Kendall test, and the non-parametric Pettitt test. While the Budyko equilibrium equation was applied to assess the factors influencing changes in inflow runoff. The research revealed a pattern of alternating high and low inflows over different periods, with an overall declining trend. During the second period (1997-2022), runoff decreased by 81.77 million cubic meters compared to the baseline period (1980-1996), representing a 31.88% reduction. The contributions of various factors to runoff changes were as follows: rainfall at 161%, potential evaporation at 8.33%, and human activities at -61%. In summary, rainfall changes had the most significant influence on runoff, followed by human activities, while potential evaporation had a comparatively minor impact.