2000—2016年叶尔羌河中下游植被覆盖动态变化遥感分析

【目的】获取干旱区内陆河流域地表植被覆盖变化信息,探讨和揭示内陆干旱地区地表植被空间演变规律。【方法】以叶尔羌河流域2000—2016年Landsat系列遥感影像数据、水文和气象数据、社会经济数据为主要数据源,基于RS、GIS及GPS等技术,采用空间数据处理、信息提取解译、海量数据建库、图属一体化、数据仓库管理技术等方法,研究分析2000—2016年流域植被覆盖时空动态变化及驱动因素。【结果】①从时间方面看,2000—2016年研究区植被覆盖面积整体呈减少趋势,即由2000年的6 025.9 km~2减少至2016年的5 620.4 km~2,减少了405.5 km~2,年减少率为0.42%,其中,主要为低盖度植被向劣盖度植被转移,研究区植被覆盖趋于退化;②从空间方面看,研究区天然植被主要分布于B段(叶尔羌河与提孜那甫河汇合处至三河汇口处),以劣植被覆盖为主,2000—2016年植被覆盖度减少区域主要集中在A段(卡群以下至叶尔羌河与提孜那甫河汇合处),且减少的植被覆盖多为劣盖度。【结论】研究区生态水平退化主要因素可归结为平原区气温升高造成的蒸散发损失加大及绿洲水土资源开发利用挤占生态用水造成的地下水位下降。

Using Remote Sensing to Unravel Spatiotemporal Change in Vegetation Coverage in Middle-low Reaches of the Yarkant Basin

【Objective】Vegetation coverage modulates hydrological processes and the purpose of this paper is to study the feasibility of using remote sensing to map the spatiotemporal change of vegetation coverage at catchment scale.【Method】The study area was at the Yarkant River Basin; the Landsat remote sensing imageries from2000—2016, along with hydrological, meteorological and socio-economic data, were used to analyzed the spatiotemporal change in vegetation coverage within the basin, with the help of GIS, GPS and other methods.【Result】①Vegetation coverage decreased from 6 025.9 km~2 in 2000 to 5 620.4 km~2 in 2016 at an annual rate of 0.42%,with the areas with poor vegetation coverage deteriorating further. ②Spatially, areas with poor natural vegetation coverage was in the region from the confluence of the Yarkant River and Tiznafu River to the confluence of the Three Rivers. Vegetation coverage loss from 2000—2016 was mainly caused by deterioration of the areas with poor vegetation from the Kaqun reservoir downstream to the confluence of the Yarkant River and Tiznafu River.【Conclusion】The deterioration of vegetation coverage in the study area was ascribed to increased evapotranspiration and dropping of groundwater table due to overusing groundwater and surface water.