自然恢复草地对黄土丘陵沟壑区浅沟侵蚀的影响
Effect of naturally restored grassland on the ephemeral gully erosion in the loess hilly and gully region.
作者信息
Wang Wen Xin, Wang Wen Long, Kang Hong Liang, Guo Ming Ming, Yang Bo, Chen Zhuo Xin, Zhao Man
机构信息
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateaus, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China.
Key Laboratory of Ecological Restoration of Mining Area in Northern Shaanxi, Yulin University, Yulin 719000, Shaanxi, China.
出版信息
Ying Yong Sheng Tai Xue Bao. 2018 Dec;29(12):3891-3899. doi: 10.13287/j.1001-9332.201812.016.
Ephemeral gully erosion is an important erosion type in hilly and gully regions of Loess Plateau. While previous studies mainly focused on ephemeral gullies in agricultural land, little is known about the effects of naturally restored grassland on ephemeral gully erosion. In this study, taking the bare ephemeral gullies as the baseline, we conducted in-situ flushing tests to explore runoff and sediment yield characteristics and erosion mechanism of grassland ephemeral gullies under the runoff conditions of 5, 10, 15, 20 and 25 L·min. Compared to the bare ephemeral gully, average flow velocity, stable runoff rate, Reynolds number and Froude number of grassland ephe-meral gullies was reduced by 25.4%-67.3%, 8.4%-26.6%, 54.9%-80.5%, 18.6%-65.1%, respectively, whereas resistance coefficient was increased by 0.09-7.18 folds. Compared to the bare ephemeral gully, the maximum sediment yield rate, stable sediment yield rate, average sediment yield rate of grassland ephemeral gullies was decreased by 55.1%-90.9%, 61.8%-95.4%, and 64.8%-92.4%, respectively. The sediment yield reduction benefit of the naturally restored grassland under the discharge flow rate of 5-25 L·min could reach 65.9%-88.8%, which decreased with increasing discharge flow rate. Compared to the bare ephemeral gully, average stream power and average shear stress of grassland ephemeral gullies was reduced by 54.9%-80.5% and 12.4%-51.1%, respectively, whereas the critical stream power and critical shear stress was increased by 1.43 folds and 33.7%, respectively. The average sediment yield of grassland and bare ephemeral gullies was signifi-cantly linearly related to average stream power and shear stress. Naturally restored grassland significantly increased the erosion resistance and reduced runoff erosion potential of ephemeral gullies.
浅沟侵蚀是黄土高原丘陵沟壑区一种重要的侵蚀类型。以往的研究主要集中在农田中的浅沟，而对于自然恢复草地对浅沟侵蚀的影响却知之甚少。在本研究中，以裸露浅沟为对照，开展原位冲刷试验，探讨了在5、10、15、20和25 L·min径流条件下草地浅沟的产流产沙特征及侵蚀机制。与裸露浅沟相比，草地浅沟的平均流速、稳定径流率、雷诺数和弗劳德数分别降低了25.4%-67.3%、8.4%-26.6%、54.9%-80.5%、18.6%-65.1%，而阻力系数增加了0.09-7.18倍。与裸露浅沟相比，草地浅沟的最大产沙率、稳定产沙率、平均产沙率分别降低了55.1%-90.9%、61.8%-95.4%、64.8%-92.4%。在5-25 L·min流量条件下，自然恢复草地的减沙效益可达65.9%-88.8%，且随流量增加而降低。与裸露浅沟相比，草地浅沟的平均水流功率和平均剪切应力分别降低了54.9%-80.5%和12.4%-51.1%，而临界水流功率和临界剪切应力分别增加了1.43倍和33.7%。草地和裸露浅沟的平均产沙量与平均水流功率和剪切应力显著线性相关。自然恢复草地显著提高了浅沟的抗侵蚀能力，降低了径流侵蚀潜力。
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