Quantitative assessment of check dam system impacts on catchment flood characteristics – a case in hilly and gully area of the Loess Plateau, China

The purpose of this study is to investigate the impact of check dams on catchment hydrological response in a small catchment on the hilly and gully area of Chinese Loess Plateau by applying a numerical model at 2 m resolution DEM. The results showed that check dams significantly increase the so-called runoff lag times (lag to generation, lag to peak and lag to end of runoff) at the channel outlet compared to catchments without check dams. Furthermore, the peak runoff discharge at the catchment outlet without check dams decreased by 93.0% compared to with check dams. The total outlet discharge, surface water stored, and infiltration were, respectively, 20.1%, 74.9% and 5.0% of the total precipitation in the check dam catchment, while 75.4%, 22.6% and 2.0% in the system without check dams. Installation of check dams also altered the spatial water distribution of maximum discharge, moving the occurrences of maximum discharge further upstream and, thus, increasing safety downstream. In conclusion, implementing check dams significantly and effectively mitigated flood processes and increased runoff infiltration upstream.