基于遥感影像的荒漠化矿区土壤含水率的影响因素分析

Affecting factors analysis of soil moisture for arid mining area based on TM images

利用野外监测和TM遥感影像数据,建立了基于热惯量的计算土壤含水率的遥感信息模型.野外监测样点平均值表明采空区与非采空区上方土壤含水率差异大,遥感反演的面域平均值则显示两者差异较小.分析了影响土壤含水率的主要因素,结果表明:土壤含水率随高程的增大而降低;采矿导致土壤渗透系数发生变化,采空区上方垂直入渗能力增强,改变了潜水补给条件和土壤表面蒸发能力,进而影响土壤含水率;考虑毛细水上升高度和植物根系所及的深度,当采前地下水埋深较小而植物根的垂直深度较大时,采矿引起的水位下降必将影响植物利用潜水;当采前地下水位埋深较大而地表植被为浅根植物时,则不会影响,而采矿引起的地表裂缝则增加了地表土壤蒸发,地表拉伸变形容易拉断植物根系,进而影响植物的生长.

The model for calculating soil moisture （SM） in terms of thermal inertia using TM image and MODIS image was developed. There existed remarkable difference between two sets of average SM calculated by limited field sampling points taken from two different sampling sites, mined site and unmined site, and there were not dis- tinct difference between two sets of average SM calculated by the model using TM image. Domain factors affecting the SM were analyzed. The SM is in inverse proportion to the elevation, and in direct proportion to the vegetable index. Coal mining resulted in the change of soil infiltration capacity. The vertical filtration index increased at the mined site, thereafter, the condition to supply ground water changed, the soil surface transpiration increased and SM changed. Whether the drop of ground water level from mining engineering affects the plant growth is upon the ground water level before mining and the depth of plant root. When the plant root is long enough and extends down- wards to reach the zone of capillary zone, ground water will be available for plant growth.