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首页> 外文期刊>Journal of arid environments >Assessing Land-cover Change And Degradation In The Central Asian Deserts Using Satellite Image Processing And Geostatistical Methods
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Assessing Land-cover Change And Degradation In The Central Asian Deserts Using Satellite Image Processing And Geostatistical Methods

机译：利用卫星图像处理和地统计方法评估中亚沙漠的土地覆盖变化和退化

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Soil and vegetation degradation around watering points has been observed in many drylands around the world. It can be recognized in spaceborne imagery as radial brightness belts fading as a function of distance from the water wells. The primary goal of the study was to characterize spatial and temporal land degradation/rehabilitation in the Central Asian drylands. Tasseled Cap's brightness index was found to be the best spectral transformation for enhancing the contrast between the bright-degraded areas close to the wells and the darker surrounding areas far from and in-between these wells. Semi-variograms were derived to understand the spatial structure present in the spaceborne imagery of two desert sites and in three key time periods (mid-late 1970s, around 1990, and 2000). A geostatistical model, namely the kriging interpolation technique, was applied for smoothing brightness index values extracted from 30 to 80 m spatial resolution images in order to assess spatial and temporal land-cover patterns. Change detection analysis, based on the kriging prediction maps, was performed to assess the direction and intensity of changes between the study periods. These findings were linked to the socio-economic situation before and after the collapse of the Soviet Union that influenced the grazing pressure and hence the land-use/land-cover state of the study sites. The study found that degradation occurred in some areas due to recent exploration and exploitation of the gas and oil reserves in the region. Another area was subject to rehabilitation of the rangeland due to a dramatic decrease in the number of livestock due to socio-economical changes after the independence of Kazakhstan in 1991.
机译：在世界许多干旱地区，都观察到了浇水点附近的土壤和植被退化。在星载图像中可以将其识别为径向亮度带随着距水井距离的增加而逐渐消失。这项研究的主要目的是表征中亚旱地的时空土地退化/恢复。发现流苏帽的亮度指数是最好的光谱变换，可增强靠近孔的明亮降解区域与远离和位于这些孔之间的较暗周围区域之间的对比度。推导了半变异函数图，以了解两个沙漠站点和三个关键时间段（1970年代中后期，1990年和2000年左右）的星载图像中存在的空间结构。地统计学模型，即克里格插值技术，被用于平滑从30至80 m空间分辨率图像中提取的亮度指数值，以便评估空间和时间的土地覆盖格局。基于克里金预测图进行变化检测分析，以评估研究期间之间变化的方向和强度。这些发现与苏联解体前后的社会经济状况有关，后者影响了放牧压力并因此影响了研究地点的土地利用/土地覆盖状况。研究发现，由于最近对该地区的天然气和石油储量进行勘探和开采，某些地区发生了退化。由于1991年哈萨克斯坦独立后社会经济发生变化，牲畜数量急剧减少，因此另一个地区需要进行牧场恢复。

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