干旱风沙区水库边缘植被-风力侵蚀的变化及成因

目的] 对干旱风沙区水库边缘植被覆盖度和土壤风力侵蚀的动态变化及其成因进行分析，为该库区风沙危害的防治提供依据。方法] 基于Landsat影像使用像元二分模型计算植被覆盖度，运用定性与定量相结合的方法，研究甘肃省瓜州县桥子水库边缘植被变化和风力侵蚀状况。结果] 2006，2011，2018年植被覆盖度分别为0.15，0.13和0.35，水库边缘的植被呈先减后增的趋势，其生长有远离水库的趋势。2006-2011年桥子库群周边环境变化剧烈，2011-2018年植被退化速度减缓。研究区强烈以上侵蚀面积比例仍较大（50%以上）。结论] 研究区植被和侵蚀变化的原因除了气候等自然因素外，地下水补给量减少，水位降低，超生态负荷扩大绿洲，不合理的种植业结构、耕作方式及牧业发展等人为因素加速了天然植被退化和局部侵蚀，而采取的草场封育、固沙造林等治理和修复措施在一定程度上延缓这一进程。建议采取生态引水、补给地下水、发展节水农业、禁垦禁牧、调整产业结构、恢复植被等抢救性措施和预防保护治理措施，以维护绿洲的持久稳定。

Evolution and Causes of Vegetation and Wind Erosion at Reservoir Edge in Arid Sandstorm Area

Objective] The dynamic changes and causes of vegetation coverage and wind erosion at the edge of the reservoir in arid sandstorm region were analyzed in order to provide a basis for the prevention and control of sandstorm hazards in the reservoir area.Methods] Taking Qiaozi reservoir at Guazhou County, Gansu Province as a study area, landsat images of the edge of Qiaozi reservoir was collected, and the pixel dichotomy model was used to calculate the vegetation coverage in the arid sandstorm area. Both qualitative and quantitative methods were used to evaluate the changes of vegetation edge and wind erosion.Results] The annual average values of vegetation coverage in 2006, 2011, and 2018 were 0.15, 0.13, and 0.35, respectively. The vegetation at the edge of the reservoir decreased first and then increased, and tended to grow away from the reservoir, and the change of vegetation coverage from 2006 to 2011 was higher than that from 2011-2018. The severe erosion area still accounted for a large proportion (>50%).Conclusion] In addition to climate, the reduction of groundwater recharge, the decrease of water level, the expansion of oasis beyond ecological load, unreasonable planting, inadequate farming methods and animal husbandry development have accelerated natural vegetation degradation and local erosion. The adoption of grassland enclosure, sand fixation and afforestation and other management and restoration measures have delayed this process to a certain extent. It is suggested that ecological water diversion, groundwater replenishment, development of water-saving agriculture, reclamation and grazing prohibition, adjustment of industrial structure, restoration of vegetation and other rescue measures as well as prevention, protection and control measures should be taken to maintain the lasting stability of the oasis.