九洲江流域水土流失现状及变化分析

Current situation and change analysis of soil erosion in Jiuzhou River Basin

为探究九洲江流域水土流失现状及变化规律,在遥感和GIS技术的支持下,结合野外实地调查,采用定性和定量相结合的方法,对九洲江流域2019年土地利用、植被覆盖情况,以及水土流失分布特征、面积和强度进行提取和计算。结果表明:2019年九洲江流域土地利用类型以有林地和水田为主,2种土地利用类型分别占流域总面积的62.0%和11.5%;植被覆盖以高覆盖度园地、林地和高覆盖度草地为主,高覆盖度园地、林地占园地、林地面积的92.3%,高度盖度草地占草地面积的96.5%。与2018年度相比,土壤侵蚀程度降低,其中,2018年轻度、中度、强烈、极强烈和剧烈土壤侵蚀地块中分别有78.7%、57.2%、47.1%、48.7%和48.6%转为微度侵蚀。研究结果对了解和掌握九洲江流域水土流失与生态环境状况,以及后期防治对策的制定提供了数据支撑。

[Background]With the rapid development of social economy,human activities have caused great damage to the surface vegetation and accelerated the soil erosion,which has seriously restricted the eco-environmental construction and sustainable development in China.However,few studies have evaluated regional soil erosion through field investigation combined with quantitative calculation of empirical model or physical model.Jiuzhou River is a typical rain-fed river with serious soil erosion in South China.[Methods]The main objective is to examine the status of soil erosion and eco-environmental construction and to provide support for the control and preventive countermeasures in Jiuzhou River,supported by remote sensing and GIS technology.The land use,vegetation cover and the distribution characteristics,area and intensity of soil erosion were extracted and calculated by the NDVI(normalized difference vegetation index),NDWI(normalized difference water index)and CSLE(Chinese soil loss equation)in the Jiuzhou River Basin in 2019,combined with field work.[Results]1)The land use types in the Jiuzhou River Basin in 2019 were mainly woodland and paddy field,accounting for 62.0%and 11.5%of the total area of the basin,respectively.2)The vegetation cover was dominated by high-coverage orchard garden,woodland and high coverage grassland.The high coverage orchard garden and woodland occupied 92.3%of the overall orchard garden and woodland area,and the high coverage grassland accounted for 96.5%of the whole grassland area.3)The degree of soil erosion decreased in 2019 compared to that in 2018.And 78.7%,57.2%,47.1%,48.7%and 48.6%of the slight,medium,intense,extremely intense and severe soil erosion plots in 2018 shifted to micro erosion in 2019,respectively.4)Severe and extremely intense soil erosion occurred in the mining land and bare land areas caused by large-scale development and construction projects.[Conculsions]Land use type,vegetation cover and soil erosion degree can accurately reflect the current situation of soil erosion in the Jiuzhou River Basin.The total area of soil erosion decreased but medium,intense and micro soil erosion increased in 2019.Soil erosion caused by human activities still has a great impact on the ecological environment.In future,erosion prevention and soil conservation should be carried out on areas with high-risk of erosion.