Search

Soil erosion is the most serious ecological and environmental problem causing land degradation and water resources pollution, which is controlled by soil and water conservation measure(SWCM). At present, it is still challenging to quantify the direct and indirect impacts of SWCM, rainfall characteristics and slope on runoff and sediment yield in loess hilly and gully region. The runoff and sediment yield of 19 runoff plots and 25 typical erosive rainfall events in Lijiangou small watershed in the loess hilly and gully region of Ningxia were investigated from 2015 to 2019. The structural equation model(SEM)was used to analyze the direct and indirect effects of rainfall characteristics, SWCM and slope on runoff and soil loss. The redundancy analysis (RDA) method was used to quantify the contribution rate of each influencing factors to the runoff reduction benefit (RRB) and sediment reduction benefit (SRB). The results show that ① the 20° slope has the best RRB, and the steep slope has better SRB; in different SWCMs, RRB and SRB of artificial shrubland are higher. ② Rainfall characteristics, SWCM and slope have no indirect impact on runoff and sediment, while 30 min maximum rainfall intensity has the largest direct impact on runoff and sediment, with direct path coefficients of 0.77 and 0.46, respectively. ③ Rainfall characteristics are the dominant factor affecting runoff, sediment and RRB; compared with rainfall characteristics, SWCM and slope are the main factors controlling SRB. ④ Runoff and soil loss will increase due to extreme erosive precipitation events caused by global warming; SWCM is very necessary to prevent runoff and soil loss; on steep slopes, the vegetation combination mainly with shrub is expected to achieve greater benefits of runoff and sediment reduction. [ABSTRACT FROM AUTHOR]