四川境内赤水河流域上中游水土流失时空变化研究

Study on the temporal and spatial variations of soil erosion in the upper and middle reaches of the Chishui river basin in Sichuan

以国家级水土流失重点治理区赤水河流域上中游(四川境内)为研究区,以2000—2015年为研究时间区间,考虑修正后的通用土壤流失方程(RUSLE)中各影响因子,综合评价得到水土流失敏感性空间分布,按照国家标准将流域土壤侵蚀由低到高分为6个等级,同时结合变化斜率法利用GIS软件平台,分析15 a期间流域水土流失情况的变化趋势,为研究区水土流失及其防治工作提供理论依据。结果表明:2000—2015年期间,占研究区总面积34. 8%的区域水土流失呈增长趋势,65. 2%的区域水土流失呈降低趋势;水土流失显著增加的区域占6. 14%,主要集中在叙永与古蔺交界的几个乡镇;水土流失显著减少的区域占29. 43%,零星分布于研究区各处,最集中分布于合江县西北方向。赤水河流域上中游(四川境内)水土流失主要以中度侵蚀为主,空间分布特征明显,呈现南高北低的格局,轻度及以下水土流失区域主要分布在北部区域,极强烈和强烈水土流失区域集中分布于南部低中山区域。15 a间呈增长趋势的区域仅占流域全区的6. 14%,充分说明长期的治理初见成效。

The research area is located in the middle and upper reaches of Chishui river basin (in Sichuan province),it is a key national water and soil loss control area. The time interval of this study was from 2000 to2015. Considering the influence factors in the Revised General Soil Loss Equation (RUSLE),the spatial distribution of water and soil loss sensitivity was obtained by comprehensive evaluation,and the soil erosion in the basin was divided into 6 grades from low to high according to the national standards. The change trend of water and soil loss in the basin during the 15 years was analyzed by using GIS software platform with the change slope method,which provided theoretical basis for water and soil loss and its control in the study area. The results showed that: water and soil loss in the region accounting for 34. 8 % of the total area showed an increasing trend,and 65. 2 % of it showed a decreasing trend from 2000 to 2015;the area with significant increase in water and soil loss accounted for 6. 14% of the total area,which mainly concentrated in several towns at the junction of Xuyong and Gulin. The area with significant decrease in water and soil loss accounted for 29. 43% of the total area,which scattered throughout the study area,and most concentrated in the northwest of Hejiang County. Water and soil loss in the upper and middle reaches of the Chishui river basin (in Sichuan province)was dominated by moderate erosion,and its spatial distribution characteristics were obvious,showing a pattern of high in the south and low in the north. The light and lower water and soil loss areas were mainly distributed in the northern region,and the strong and extremely strong water and soil loss areas were concentrated in the southern low mountain region. The area that showed an increasing trend during the past 15 years accounted for only 6. 14% of the entire basin,which fully demonstrated the success of the long-term governance.