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How does land use/cover influence gully head retreat rates? An in-situ simulation experiment of rainfall and upstream inflow in the gullied loess region, China
Land Degradation & Development ( IF 3.6 ) Pub Date : 2021-01-20 , DOI: 10.1002/ldr.3892 Hongliang Kang 1 , Wenlong Wang 1, 2 , Mingming Guo 3 , Jianming Li 2, 4 , Shi Qianhua 1
Land Degradation & Development ( IF 3.6 ) Pub Date : 2021-01-20 , DOI: 10.1002/ldr.3892 Hongliang Kang 1 , Wenlong Wang 1, 2 , Mingming Guo 3 , Jianming Li 2, 4 , Shi Qianhua 1
Affiliation
Land use/cover plays a crucial role in gully head retreat (GHR). However, little is known about how land use/cover influences GHR rates. An in situ simulation experiment of rainfall and upstream inflow was conducted in a gullied loess region to investigate hydraulic erosion, mass movements, and linear GHR processes under three types of land use/cover (bare land, grassland, and shrub-grass land). The results showed that the average linear GHR rates on grassland and shrub-grass land were 87–89% and 72–81% lower than that on bare land (0.99–2.06 cm min−1), respectively. Gully heads retreat by hydraulic and gravitational erosion. In the case of hydraulic erosion, upstream runoff incision is dominant on bare land, while undercutting by on-wall and jet flow dominates on grassland and shrub-grass land. In the case of mass movement, collapse dominates with a frequency of 62–100%, of which gully sidewall collapse is most common, especially on bare land and it acts to widen the gully. Gully headwall collapse dominates on grassland and shrub-grass land to cause retreat of the gully head. Overall, on bare land, upstream runoff incision dominates GHR. However, on grassland/shrub-grass land GHR is mainly driven by the undercutting of on-wall and jet flow and subsequent gully headwall collapses. As a consequence, the GHR length on bare land exponentially increases over time, while on grassland or shrub-grass land, it discretely increases as an analogous step function. Moreover, the average linear GHR rate on grassland was considerably lower than that on shrub-grass land, implying that an optimized vegetation restoration pattern enhances GHR control.
更新日期：2021-01-20
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