淅川县石质荒漠化土地坡度分级及岩性特征

Study on Land Slope and Lithology Characteristics of Stone Desertification in Xichuan County

淅川县是南水北调中线工程重要水源地及渠首所在地,全县石质荒漠化土地面积745.539 3 km2、占土地总面积的26.44%,区域生态环境问题十分突出。利用DEM、地质图等资料,基于3S技术对淅川县石质荒漠化土地坡度及岩性特征进行研究,结果表明:淅川县石质荒漠化主要发生在碳酸盐岩组区域、8°~25°坡面,8°~25°石质荒漠化土地面积为588.001 5 km2、占石质荒漠化土地总面积的78.87%;石质荒漠化土地面积随坡度加大的变化,在坡度小于25°时呈上升趋势,在坡度超过25°时呈下降趋势,坡度超过35°的面积只有2.679 3 km2、仅占0.36%;淅川县土地岩性主要为碳酸盐岩组、碎屑岩组、多层土体、变质岩组、侵入岩组,各岩组区域石质荒漠化土地分布面积分别为461.59、164.54、119.20、66.86、40.63 km2,石质荒漠化发生率分别为58.26%、23.56%、1.96%、30.74%、24.98%,在碳酸盐岩组区域分布面积和发生率明显高于其他岩性区域。

Xichuan County is the core source area and the main flood zone of the Mid-Route of the South-to-North Water Transfer Project and also the location of the head work,which the land area of the stone desertification is 745.539 3 km2,which accounts for 26.44% of the total land area,which cause very serious problems of soil erosion and regional ecological resources. Slope and lithology are important factors of soil erosion development. Using DEM geological map,etc,the paper studied the land slope and lithology characteristics of stone desertification in Xichuan County based on 3 S technique. The results show that the stone desertification in Xichuan County mainly occurred in the area of carbonate formation,range of 8°-25° and carbonate rocks; the total area of 8°-25° is 588.001 5 km2,which accounts for 78.87%; stone desertification land slope increases with the increase of slope at less than 25°,and the slope over 25° decreases with the increase of slope,the minimum area of 〉35° is 2.679 3 km2,which is only 0.36%. The land lithology of Xichuan County is mainly carbonate rock group,clastic rock group,multilayer soil,metamorphic rock group and intrusive rock group. The land distribution area of stone desertification in each rock area is 461.59 km2,164.54 km2,119.20 km2,66.86 km2 and 40.63 km2 respectively and the average incidence are 58.26%,23.56%,1.96%,30.74% and 24.98%respectively. The distribution area of stone desertification in carbonate formation area is obviously higher than that of other lithologic regions.