江苏省平原沙土区河沟边坡土壤分离速率及其影响因素

Soil detachment rate and its influencing factors of gully slope in the plain sandy area of Jiangsu province

江苏省平原沙土区河沟边坡水土流失现象严重,为探明河沟边坡土壤分离特征及其影响因素,利用变坡式水槽冲刷试验,在3个坡度(10°、20°和30°)和2个流量(0.5和1.5 L/s)条件下,对江苏省3类沙土区内河沟边坡土壤开展土壤分离速率研究,了解3类沙土区土壤基本理化性质的差异,明确不同沙土区的土壤分离速率,并分析土壤分离与土壤性质、坡度、流量及径流特征因子的关系。结果表明:1)江苏省平原沙土区河沟边坡土壤砂性大、养分贫瘠,黄河故道沙土区、沿海平原沙土区和通南高沙土区的砂粒质量分数分别为80.64%、57.24%和62.22%;2)黄河故道沙土区平均土壤分离速率为218.0 kg/(m^(2)·s),沿海平原沙土区为60.9 kg/(m^(2)·s),通南高沙土区为17.1 kg/(m^(2)·s),且三者之间存在显著差异;3)3类沙土区土壤分离速率随坡度和流量的增大逐渐增大;4)在土壤特性因子中,土壤分离速率与分形维数、砂粒含量呈极显著正相关关系(P<0.01),与水稳性团聚体含量、粉粒、黏粒和有机质含量呈极显著负相关关系;在径流特性因子中,土壤分离速率与雷诺数、流速、水流功率等呈极显著正相关关系。研究首次明确江苏平原3类沙土区典型河沟边坡土壤分离速率及其影响因素,可丰富江苏平原河沟边坡土壤侵蚀研究理论,为边坡土壤侵蚀防治提供科学支撑。

[Background]Soil and water loss of gully slope in plain sandy area of Jiangsu province is severe.The soil detachment rate and the main controlling factors of gully slope in plain sandy area of Jiangsu province are unclear,which limits the understanding and effective control of erosion in plain sandy area.[Methods]Under the conditions of 3 slope gradients(10°,20°and 30°)and 2 flow rates(0.5 L/s and 1.5 L/s),the soil detachment rate of typical gully slope in 3 types of plain sandy area in Jiangsu province was investigated by variable-slope flume scouring experiments.[Results]1)Soil sand content was high and nutrient was poor of gully slope in plain sandy area of Jiangsu province.The sand content in the plain sandy area of the old Yellow River,the coastal plain sandy area and the high sandy area of Tongnan was 80.64%,57.24%and 62.22%,respectively.2)There were significant differences in the average soil detachment rate of gully slope in the three plain sandy areas.The average soil detachment rate was as follows:plain sandy soil area of the old Yellow River(218.0 kg/(m^(2)·s))>coastal plain sandy area(60.9 kg/(m^(2)·s))>high sandy area of Tongnan(17.1 kg/(m^(2)·s)).3)The soil detachment rate in the 3 types of plain sandy areas gradually increased with the increasing of slope gradient and flow rate.4)In soil characteristic factors,soil detachment rate was significantly correlated with water-stable aggregate content,sand content and organic matter content(P<0.01).In runoff characteristic factors,soil separation rate was significantly positively related to flow power,flow velocity and Reynolds number(P<0.01).[Conclusions]The study clarified the soil detachment rate and its influencing factors of typical gully slope in the three types of plain sandy areas in the Jiangsu Plain at first time.The result of the study may enrich the research theory of gully slope erosion and provide scientific support for gully slope erosion control.