Due to the specific hydrothermal conditions of dry-hot valleys, temperature changes caused by the development of large-scale hydropower projects may be more extreme than they are in other regions. In this study, we analyzed these temperature changes at four hydropower stations in both dry-hot and non-dry-hot valleys. Based on the calculated relative temperatures of the downstream river and the areas surrounding the reservoirs, we employed two indices to quantify the influence of the reservoirs on the temperatures of these two regions: the downstream river temperature change and the reservoir effect change intensity. Our results are as follows: (a) In the downstream rivers, the temperature regulation effect was more pronounced in the wet season; in the regions surrounding the reservoirs, the temperature regulation effect was more pronounced in the dry season. (b) The downstream river temperature in both the dry-hot and wet-hot valleys exhibited noticeable warming in both the wet and dry seasons, while the cold-dry valley was characterized by cooling in the dry season and warming in the wet season. With the exception of the Liyuan station (where the influence of the reservoir on the downstream temperatures only extended to a distance of 9 km from the dam) during the dry season, the existence of the hydropower stations affected the temperatures of the entire downstream region. (c) For the areas surrounding the reservoir, the presence of a hydropower station mainly caused the temperatures in the dry-hot valleys to rise and the temperatures in the non-dry-hot valleys to decrease.
Keywords: comparative study; downstream river temperature change; dry‐hot valley; relative temperature; reservoir effect change intensity.
© 2021. The Authors. GeoHealth published by Wiley Periodicals LLC on behalf of American Geophysical Union.