Distinguishing the impacts of human activities and climate variability on runoff and sediment load change based on paired periods with similar weather conditions: A case in the Yan River, China

Runoff and sediment loads from river basin are largely affected by the interplay of climate variability and human activities within the basin. However, distinguishing the impacts of climate variability and human activities would vastly improve our knowledge of water resources, climate variability and climate adaptation, and watershed management. We propose a new and simple method to determine the impact of human activities within paired datasets under the same or similar weather conditions (SWC). These weather conditions cover one or more meteorological elements such as precipitation, temperature, or evaporation. If there are two or more periods with similar weather conditions but different runoff, the relative runoff and sediment load changes can be considered a consequence of human-induced land surface changes. This study will report on the application of this new method, using the Yan River Basin in China as a case study. We found 10 sets PPs (paired periods) in 1. year intervals and 12 sets of PPs in intervals of 3. years when (1) there was a 2.0% and 1.0% difference of annual precipitation and annual ET0, respectively, (2) the relationship between monthly precipitation and ET0 of PPs was significant (. P