A probabilistic conceptual model to attribute runoff variations to human activity.

A new probabilistic conceptual model, named the Assessment Model of Human Impact on Runoff Based on Stationarity Hypothesis (AMHIRBSH), was developed to attribute runoff variations to human activities through evaluating the changes in the runoff–runoff relationship (i.e. that between runoff of different watersheds). The AMHIRBSH was then applied to the Baiyangdian drainage basin, North China. After applying the Mann-Kendall test for trend and the Pettitt test for breakpoint, the runoff over the Baiyangdian drainage basin was shown to have had a breakpoint in approximately 1979, which split the time series into a baseline period (pre-1979) and an altered period (post-1979). The runoff was greatly reduced between these two periods. The runoff–runoff relationship of the Wangkuai and Xidayang sub-watersheds was evaluated using a copula function which showed it to have a non-stationarity degree of 35.64%, likely induced by massive afforestation programmes. This method provides an innovative perspective for attributing runoff variations to human activities. [ABSTRACT FROM AUTHOR]