宁夏中部干旱带土地利用/覆被变化对区域蒸散及土壤水分的影响

This study assesses the effects of land-use/land-cover (LULC) change on regional evapotranspiration and drought in arid regions of central Ningxia province using remote sensing data of different periods over the past nearly two decades. Remote sensing images are interpreted by considering land-use/vegetation type, in order to analyze the situation of vegetation rehabilitation upon prohibited grazing over the past decade.By the comparative analysis of three remotely sensed evapotranspiation model:(single-layer,double-layer and TS-NDVI), to establish a optimal remotely sensed evapotranspiration model for the study area and obtain information on spatiotemporal variability of evapotranspiration level by remote sensing retrieval. Based on the above,the basic laws of LULC influencing evapotranspiration level are analyzed, and the effects ofLULC change on regional water circulate process regional evapotransipiration in arid regions are explored. Thus revealing the relationship among soil, vegetation and waterin the study area.The results are of practical significance to vegetation rehabilitation in degraded ecosystems in arid regions of central Ningxia, which provide a rational reference for assessing the implementation effect of national ecological control policy in local regions.

本课题以宁夏中部干旱带为研究区域，选取该研究区近二十年来不同时期遥感资料，按土地利用/植被类型进行遥感数据解译，分析禁牧十年植被的恢复情况。通过对三种遥感蒸散模型的比较(单层模型，双层模型，温度植被关系模型)，建立宁夏中部干旱带最佳遥感蒸散模型,获得遥感信息反演的蒸散时空变异结果。在以上基础上分析土地利用/植被覆盖影响蒸散的基本规律；探讨干旱带土地利用/覆被变化对区域水循环过程的影响，从而揭示土壤、植被和水之间的相互作用关系。研究成果对宁夏中部干旱带退化生态系统的植被恢复具有重要的实际意义，同时为评估该区国家生态调控政策的实施效果提供科学依据。

干旱区土地覆被变化及水资源问题是干旱区生态环境研究的核心问题。本项目以宁夏中部干旱带为研究区域，研究了禁牧10多年来植被恢复情况，建立了遥感蒸散模型，分析了不同土地利用覆被的蒸散量，及主要土地覆被类型的土壤含水量。研究结果表明：（1）从2003-2015年盐池土地利用变化情况看高覆盖草地，中覆盖度草地，建设用地、水体、水浇地的面积呈增加趋势，而未利用地、林地、旱地和低覆盖度草呈减少趋势。（2）研究区的几种主要土地利用类型中耕地的日蒸散量最大为2.24mm，林地次之为1.35mm，未利用地最小为0.69mm。因此耕地转草地是会降低蒸散量，草地转林地会增加蒸散量。（3）在0-100cm土层研究区荒漠草原区土壤含水量总趋势以人工苜蓿最大，天然草地第二，草地和柠条混交林次之，柠条林地最低。本项目阐明了干旱地区土壤、植被和水之间的相互作用关系，也为宁夏中部干旱带退化生态系统的植被恢复具有重要的实际意义。