玛纳斯河流域土壤盐渍化时空动态变化

Spatiotemporal Change of Soil Salinization in Manasi River Basin

土壤盐渍化是土地荒漠化的重要方式之一,研究土壤盐渍化时空动态变化对土地管理利用具有重要意义。以玛纳斯河流域为研究区,采用1975年、1990年、2000年、2014年4期遥感影像为数据源,结合野外调查分析,分别提取了玛纳斯河流域土壤盐渍化信息,运用统计和空间分析方法对研究区近40a的土壤盐渍化时空动态变化进行研究,并对引起其变化的驱动因子进行了分析。结果表明:(1)近40年玛纳斯河流域土壤受不同程度盐渍化侵扰复杂变化,总体呈逐渐减轻的趋势,其中重度盐渍化减少了2 369.4km2,中度盐渍化处于稳定波动状态,轻度盐渍化增加了1 408.0km2,耕地面积增加了3 443.5km2;(2)玛纳斯河流域土壤盐渍化在空间上分布具有明显的区域性,其中重度、中度盐渍化主要分布在中游水库周围以及下游与古尔班通古特沙漠的过渡带,轻度盐渍化与耕地镶嵌分布;(3)玛纳斯河流域土壤盐渍化1975—1990年在空间总体变化上呈加重的趋势;1990—2000年在空间分布上呈减轻的趋势;2000—2014年又出现大面积的恶化趋势;(4)政策实施以及经济刺激是推动土壤盐渍化治理的有效措施。随着全球气候变暖,耕地面积的不断扩大,水资源利用的不合理,这将势必增加土壤盐渍化的不确定性。

Soil salinization is one of the main forms of land desertification.Therefore,study on the dynamic changes of soil salinization is very important for land management and utilization.Soil salinization information in the Manas River basin was extracted from four sets of Landsat TM/ETM＋images in 1975,1990,2000 and 2014.Then spatiotemporal dynamic changes were analyzed using statistical and spatial analysis methods.The results show that：（1）the severe salinization area reduced by 2 369.4km2;the moderate salinization area remained stable;the slight salinization area increased by 1 408.0km2;and the cultivated land area increased by 3 443.5km2 from 1975 to 2014;（2）the distribution of soil salinization had the obvious spatial characteristics,with the severe and moderate salinization areas mainly distributing around the reservoir in the middle reaches and around the Gurbantunggut Desert in the downstream,mild salinization embedded in the cultivated land;（3）the degree of soil salinization had increased from 1975 to 1990,decreased from 1990 to 2000,and deteriorated from 2000 to 2014;（4）valid policy and economic measure are effective to improve the management of soil salinization.With the global climate warming,the continuous expansion of cultivated land area,and the unreasonable utilization of water resources,the uncertainty of soil salinization change will increase.