Abstract:
Vegetative trapping of heavy rainfall is an important mechanism for mitigating frequent rain-induced flood disasters in the context of global warming. To investigate the role of natural vegetation in trapping heavy rainfall following the widespread implementation of the "the Grain for Green" project in the Loess Hilly and Gully area, an automatic soil moisture monitoring system was employed to continuously monitor the soil moisture content in the top 10 m on one shrub-covered slope and three herbaceous slopes during six heavy rainfall events occurring in the Fangta watershed of the Ansai District, Shaanxi Province, from 2019 to 2022. The results showed that the maximum infiltration depth of the herbaceous slopes was approximately 200 cm during the heavy rainfall events, while for the shrub-covered slope, it was only 100 cm. Furthermore, the shrub-covered slope exhibited superior rainfall interception compared to the herbaceous slopes. The trapping efficianncy of the herbaceous slopes improved with each successive year of "Grain for Green" project implementation. Additionally, natural shrub-covered slopes displayed a trapping efficiency of up to 60.8% during low-intensity, short-duration rainfall events, and 40.8% during high-intensity, long-duration rainfall events. Therefore, it is advisable to strategically conserve and allocate shrub-herbaceous ecosystems within the Loess Hilly and Gully area to enhance the storage and mitigation capacity of vegetation and soil in response to heavy rainfall.