Effect of Check Dam on Sediment Load Under Vegetation Restoration in the Hekou-Longmen Region of the Yellow River

Zhanbin Li,Zeyu Zhang,Yang Zhao,Zhi Yang,Junrui Chai,Li Chen,Xia Zhang,Kunxia Yu

doi:10.3389/fenvs.2021.823604

Abstract

With years of vegetation restoration and check dam construction on the Loess Plateau, the sediment load of the middle reaches of the Yellow River have decreased sharply; however, the effects of check dam on this decrease of sediment load with such extensive vegetation restoration remains unclear. In order to further clarify the effects of check dam on sediment load reduction under vegetation restoration, we calculated vegetation coverage and check dam index based on multi-source remote sensing data, and calculated sediment reduction rate caused by human activities by Mann-Kendall statistical test and double cumulative curve, then established regression equations incorporating the check dam index and the sediment reduction rate using data from different geomorphic regions with different vegetation coverages. The results showed that sediment load in the Hekou-Longmen region and its 17 tributaries decreased significantly every year, and the change in sediment load could be divided into 3 typical periods: the base period (P1), the period mainly impacted by check dam construction (P2) and the period with comprehensive impact of check dam construction and vegetation restoration (P3). Compared with sediment load of the tributaries during P1, the sediment load decreased by 60.96% during P2 and by 91.76% during P3. Compared with the contribution of human activities to the reduction in sediment load in P2, the contribution of human activities in P3 increased significantly, while that of precipitation decreased slightly. The sediment reduction effect of check dams is greater in basins with low vegetation coverage than in basins with high vegetation coverage. There are differences in sediment reduction effect of vegetation restorations in different geomorphic regions, and the effect of vegetation restoration alone have certain upper limits. Such as, the upper limit of sediment reduction rate of vegetation restoration for rivers flowing through the sandstorm region is 47.86%. Hence, only combined the construction of check dam with vegetation restoration can it achieve more significant sediment reduction benefit and control soil erosion more effectively.

Highlights

Soil erosion is a geomorphologic land degradation process that may cause environmental and property damage
Based on check dam construction and vegetation restoration, the change in sediment load in the Hekou-Longmen region could be divided into 3 typical periods: the base period (P1, 1952–1979), characterized by a large sediment load and few control treatments; the period mainly impacted by check dam construction (P2, 1980–1999); and the period with comprehensive impact of check dam construction and vegetation restoration (P3, 2000–2017)
The results of this study showed that vegetation restoration in different geomorphic regions had different effects on sediment reduction, and sediment reduction effects attributed to vegetation restoration had certain upper limits in most regions

Summary

Introduction

Soil erosion is a geomorphologic land degradation process that may cause environmental and property damage. The Hekou-Longmen region on the Loess Plateau is one of the main sources of rainstorms and floods in the middle reaches of the Yellow River. This region is the main source area of coarse sediment in the Yellow River: the interval coarse sediment amount of the region accounts for 73% of the Yellow River coarse sediment amount, while the area of the region accounts for 14.8% of the Yellow River basin (Xu, 2004). Check dam construction and vegetation restoration on the Loess Plateau have played important roles in controlling soil erosion and reducing river sediment load (Yang et al, 2008; Zhao et al, 2014; Chen et al, 2016)

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