A tributary-comparison method to quantify the human influence on hydrological drought

Quantifying the influence of human activities on hydrological drought is of great significance to sustainable water resource management, but it remains difficult. The key to solving this problem is determining how to scientifically select the natural reference tributary. On the basis of existing research, this paper puts forward a tributary-comparison method that combines the Drought Propagation Intensity Index (DPI) with the human activity index to preliminarily and quantitatively determine the natural reference tributary from among all tributaries and then quantify the influence of human activities on hydrological drought in other tributaries. The empirical research was carried out in the upper reaches of the Shiyang River in the eastern area of Qilian Mountain. The results showed that, firstly, at the annual and seasonal scales, the tributaries in the upper reaches of the Shiyang River changed from hydrological humidification to hydrological aridification, from west to east, from 1961 to 2016. On the whole, the hydrological aridification of Huangyang River in the central part was the most serious, but its hydrological drought duration and drought Intensity showed a downward trend at a monthly scale. Secondly, using the tributary-comparison method, Xiying River was quantitatively selected as the natural reference tributary, and the influence of human activities on hydrological drought in other tributaries was quantified. On the whole, human activities will reduce hydrological drought duration and enhance hydrological drought intensity. The empirical study further proved that the tributary-comparison method has strong applicability in multi-tributary areas with obvious differences in human activities and provides a useful supplement to existing research methods. According to this method, tributaries that are weakly affected by human activity (or not affected at all) can be selected, and the tributaries least affected by human activity can also be identified. On this basis, the influence degree and direction of human activities in other tributaries on hydrological drought can be quantified.

Automated summary

By using the tributary-comparison method, this study conducted empirical research in the upper reaches of the Shiyang River in the eastern area of Qilian Mountain. The results showed a transition from hydrological humidification to aridification in tributaries at the annual and seasonal scales, with human activities reducing hydrological drought duration and enhancing intensity. The method can be applied in areas with varying human activity levels, providing a useful supplement to existing research methods.