干旱区人工绿洲水土环境脆弱性评价

Vulnerability Assessment of Soil and Water Environment in Irrigated Area of Arid Area

针对干旱区人工绿洲水土环境脆弱性难以定量化描述的问题,以甘肃省景泰川电力提灌灌区为研究区,通过数据收集和分析,选取直接参与驱动区域水土环境分异的土壤盐分、土地利用类型、植被覆盖度、土壤电导率、地表灌水量、地下水矿化度、地下水埋深、海拔、坡度、年均降水量、年均蒸发量、年均气温12个指标,基于云理论改进层次分析法确定各指标权重,以ArcGIS软件为技术平台将各指标空间分布结果按相应权重进行空间叠加,实现研究区水土环境脆弱性空间分异特征的可视化表达。结果表明:研究区水土环境脆弱性基本保持在Ⅰ~Ⅲ级,总体空间分布格局呈现西低东高的分布特征,重度脆弱、极度脆弱区域集中分布在灌区东部封闭型水文地质单元;土壤盐分、植被覆盖度、土地利用类型、地表灌水量是影响区域尺度水土环境脆弱性的主要因素。

Aiming at theissue that the water and soil environmental vulnerability of artificial oasis in arid areas is difficult to quantitatively describe, this study used the Jingtaichuan electric power lifting irrigation area in Gansu Province as the research area. Through outdoor data collection and indoor test analysis, it selected 12 index factors of soil salinity, land use type, vegetation coverage, soil conductivity, surface irrigation, groundwater salinity, groundwater depth, altitude, slope, annual average precipitation, annual average evaporation and annual average temperature that directly participated in the process of driving regional water and soil environmental differentiation. It determined the weight of each index factor based on the improved analytic hierarchy process of cloud theory and used ArcGIS software as the technical platform to nest and superimpose the spatial distribution result of each index according to the corresponding weight to realize the spatial differentiation characteristics of the water and soil environment vulnerability in the study area visual expression. The results show that the water and soil environmental vulnerability of the study area is basically maintained below level Ⅰ-Ⅲ, and the overall spatial distribution pattern presents a distribution characteristic of low in the west and high in the east. The severely vulnerable and extremely vulnerable areas are concentrated in the closed hydrogeological unit in the eastern part of the irrigation area. It can be seen from the weight of each index factor that soil salinity, vegetation coverage, land use type and surface irrigation volume are the main driving factors that affect the vulnerability of water and soil environment at the regional scale.