## 4 Discussion  
### Impact of Reservoir Construction on Climate Change  
The impact of reservoir construction on localized climate change is a complex and multifaceted issue. In this study, a comparative analysis of temperature and precipitation before and after the construction of several reservoirs reveals notable changes in local climate characteristics (Figure 6). Following construction, the mean annual temperature stabilized, suggesting that reservoirs effectively mitigated the broader trend of warming [34]. The impact of reservoir construction on temperature varies by season. Temperature changes were most pronounced in spring and summer. In spring, the rate of temperature decrease slowed compared to pre-construction levels (Table 3). This may be due to the increased water surface area of the reservoirs, which enhances heat capacity and evapotranspiration, thereby slowing the rate of temperature decline [35]. In summer, increased evapotranspiration from the reservoir had a dual effect: it lowered daytime temperatures through evaporation and raised nighttime temperatures due to the water body's thermoregulatory effect, resulting in a reduced daily temperature range. These findings suggest that reservoirs significantly modulate local temperature fluctuations by increasing the water body's surface area. In winter, the regulating effect of reservoirs on air temperature is smaller, and the trends before and after construction are similar, indicating that reservoirs have a more limited impact on air temperature during the winter months. Additionally, some reservoirs exhibited less temperature change after construction, possibly due to their fundamental attributes, topographic features, and the climatic conditions of their regions [36]. These factors may have inhibited the significant moderating effect of the reservoirs on temperature in certain areas, leading to slower temperature changes. Figure 8: Correlation analysis between reservoir attributes and land types. Reservoir construction directly increases the size of the watershed, leading to an increase in regional evapotranspiration, which subsequently affects precipitation variability. As a result, reservoir storage significantly influences local precipitation [37]. Seasonal analysis revealed that summer precipitation increased after reservoir construction, particularly around large reservoirs (Figure 3). This is primarily due to evaporation from reservoirs, which raises local humidity and stimulates convective activity, resulting in increased precipitation. In contrast, changes in winter precipitation were more modest, and reservoirs had a smaller impact on winter precipitation. Different reservoirs exhibit varying degrees of precipitation regulation, with larger reservoirs (e.g., ZG and KY) showing reduced precipitation variability, suggesting that reservoir construction has a more pronounced effect on local climate change. Furthermore, reservoirs alter the spatial distribution of precipitation by modifying local topography and airflow patterns, resulting in more complex precipitation variability [38]. The annual mean and slope changes before and after reservoir construction indicate that the reservoir exerts a sustained local climate regulation effect, with the specific impact pattern varying across different regions. Using the Mann-Kendall (MK) test for mutation detection in climate data, this study identified a significant turning point in the inter-annual variation in temperature (T) and precipitation (P) following reservoir construction (Figure 9). The temperature trend shift mirrored that observed in high-latitude regions, confirming that reservoir construction had a moderating effect on the local climate [39]. The turning point in precipitation patterns occurred a few years after reservoir construction, consistent with findings from other studies suggesting that reservoirs initially have a substantial impact on precipitation regulation, which gradually stabilizes over time [40; 41].