Assessing the Impact of Terraces and Vegetation on Runoff and Sediment Routing Using the Time-Area Method in the Chinese Loess Plateau

Abstract

Terracing and vegetation are an effective practice for soil and water conservation on sloped terrain. They can significantly reduce the sediment yield from the surface area, as well as intercept the sediment yield from upstream. However, most hydrological models mainly simulate the effect of the terraces and vegetation on water and sediment reduction from themselves, without considering their roles in the routing process, and thus likely underestimate their runoff and sediment reduction effect. This study added the impact of terraces and vegetation practice on water and sediment routing using the time-area method. The outflow in each travel time zone was revised in each time step by extracting the watershed of the terrace units and the vegetation units and calculating the water or sediment stored by the terraces or held by the vegetation. The revised time-area method was integrated into the Land change Model-Modified Universal Soil Loss Equation (LCM-MUSLE) model. Pianguanhe Basin, in the Chinese Loess Plateau, was chosen as the study area and eight storms in the 1980s and 2010s were selected to calibrate and verify the original LCM-MUSLE model and its revised version. The results showed that the original model was not applicable in more recent years, since the surface was changed significantly as a result of revegetation and slope terracing, while the accuracy improved significantly when using the revised version. For the three events in the 2010s, the average runoff reduction rate in routing process was 51.02% for vegetation, 26.65% for terraces, and 71.86% for both terraces and vegetation. The average sediment reduction rate in routing process was 32.22% for vegetation, 24.52% for terraces, and 53.85% for both terraces and vegetation. This study provides a generalized method to quantitatively assess the impact of terraces and vegetation practice on runoff and sediment reduction at the catchment scale.

Attributing trend in naturalized streamflow to temporally explicit vegetation change and climate variation in the Yellow River Basin of China

“…To identify the interactive effect of climate variables and vegetation on streamflow trend, we additionally designed the Scenario S6 to simulated the actual trend of streamflow based on dynamic climate variables and vegetation from 1982 to 2018, thus representing the combined effects from both climate and vegetation. Due to interactive effects of predictor variables on response variable can be interpreted as the second-order or higher-order terms in Multi-point Taylor expansion (Bai et al, 2019), the interactive effect of climate variables and vegetation can be derived as follows:…”

Local knowledge and practices towards the ecological restoration of selected landscape in Atok, Benguet, Philippines

“…The local communities established ripraps and bench terraces for farms with steep slopes (Figures 3 and 4) to control soil erosion, and at the same time, maximizing the land for agricultural production. Surface run-off and soil loss are reduced by rock barriers, hedgerows, and terraces (Dano and Siapno 1992;Bai et al 2019). Deng et al (2021) highlighted the contributions of terracing in preventing soil erosion, conserving water, and increasing agricultural production.…”

On-site and Off-site Effects of Soil Erosion: Causal Analysis and Remedial Measures in Agricultural Land - a Review

“…A series of laboratory flume simulation experiments have shown that vegetation could reduce the mean velocity by 31-65% (Pan & Shangguan, 2006). Researchers also found that the average runoff and sediment reductions were 51.02% and 32.22% for soil with vegetation respectively (Bai et al, 2019).…”

“…Terraces are more favorable in agricultural land with steep slopes ranging from 16% to 40% with high erodibility factor and not in sandy and coarse soil (IWRM, 2016). It is shown that terracing reduces soil erosion up to 99% (Bai et al, 2019).…”