不同灌草格局对砒砂岩区土壤剥蚀特征的影响

Effect of Different Shrub and Grass Patterns on Soil Detachment Characteristics in Pisha Sandstone Area

探究水流驱动下土壤剥蚀特征对阐明土壤侵蚀机制和规避水土流失风险具有重要意义。通过野外放水冲刷试验,以砒砂岩区灌丛分别位于坡下(SL)、坡中(SM)、坡上(SU)的灌草坡面和草地坡面(GL)为对象,裸坡(BL)作为对照,探讨了该区坡面土壤剥蚀和水动力参数对不同灌草格局的响应特征及其相互关系,结果表明:(1)不同灌草格局可以通过削弱径流过程中的水流动能来降低坡面土壤的剥蚀程度,砒砂岩区坡面土壤剥蚀率整体介于0.055~0.469 g/(m^(2)·s),其中SL格局土壤剥蚀率最低[均值0.098 g/(m^(2)·s)],是降低土壤剥蚀程度的最佳植被布设措施。(2)不同格局土壤剥蚀率、水流功率及单位水流功率整体呈现出BL>GL>SU>SM>SL的趋势,水动力参数中水流功率与土壤剥蚀率的拟合效果最优,可以较好地描述该区坡面土壤剥蚀特征。研究可为砒砂岩区土壤侵蚀预测模型的构建提供科学依据。

Exploring the characteristics of soil detachment driven by flow is of significance to elucidate the mechanism of soil erosion and to avoid the risk of soil loss. In this study, the shrubs on the lower(SL), middle(SM) and upper(SU) slope and grass land slope(GL) were taken as research objects, and bare land slope(BL) was taken as control. The response characteristics of different vegetation patterns to soil detachment and the relationship between soil detachment rate and sediment separation characteristics were studied by field erosion test in Pisha sandstone area. The results show that:(1) different shrub—grass patterns could reduce soil detachment degree of slope by weakening the flow kinetic energy in the runoff process;under the three flow scouring degree(15, 20, 30 L/min), the soil detachment rates of the Pisha sandstone area ranged from 0.055 to 0.469 g/(m^(2)·s), among which the soil detachment rate of pattern SL was the lowest [0.098 g/(m^(2)·s)], which was the best shrub—grass arrangement measure to reduce the erosion degree of soil;(2) soil detachment rate, flow stream power, flow unit stream power in different shrub—grass patterns decreased in the order: Pattern BL>Pattern GL> Pattern SU>Pattern SM>Pattern S;the flow stream power was the best hydrodynamic parameter to simulate soil detachment rate, and it could better simulate the slope soil detachment characteristics of slope in this area. This study can provide data support for the analysis of soil detachment characteristics and mechanisms in the future, and provide scientific basis for reasonably constructing slope soil erosion production model in the Pisha sandstone area.