*4.3. Reliability Analysis of the Water and Sediment Reduction E*ffi*ciency of Terraces and Vegetation*

Liu et al. [78,81] introduced a runoff coefficient and sediment yield coefficient to discuss the flood and sediment yield for different vegetation conditions at the catchment scale in the Loess Plateau. To analyze the reliability of the simulation results, we also calculated the runoff coefficient and sediment yield coefficient of each event in the Pianguanhe Basin, and compared with the results of Liu et al. [78], as shown in Figure 9a,b. The runoff coefficient is the runoff yield per unit of precipitation per unit area, while the sediment yield coefficient is the sediment yield per unit of precipitation per unit area. In Liu et al. [78], the runoff coefficient was calculated based on annual runoff and precipitation data, and the latter only considered rainfall greater than 25 mm. In this study, the runoff coefficient was calculated based solely on storm event discharge and rainfall data. Thus, there is a disparity between the calculation results of these two studies, but yet the results are comparable to those of Liu et al. [78]. The runoff coefficient decreased along with the increase of the vegetation coverage. The vegetation

coverage of the 1980s and 2010s was 16.17% and 46.29%, respectively, and the average runoff coefficient decreased from 0.12 m3/(mm·km2) in the 1980s to 0.07 m3/(mm·km2) in recent years.

Similarly, the sediment yield coefficients calculated from the event data in this study are different from those of Liu's results based on calculations using annual data, and yet the results are comparable. The sediment yield coefficients also decreased along with the increase of vegetation coverage. The average sediment yield coefficient decreased from 80.68 t/(mm·km2) in the 1980s to 21.93 t/(mm·km2) in recent years.

**Figure 9.** Comparison of runoff generation coefficient (**a**) and sediment yield coefficient (**b**) in this study and in Liu's study.
