基于GIS的区域植被-土壤生态系统需水定量测评——以陕北延安地区为例

根据延安地区各气象站点连续30年的气象资料和各土肥站点连续10年的土壤含水实测资料，通过经验模型、实地观测和GIS空间分析相结合的方法，提出了干旱半干旱地区植被-土壤复合系统的最小生态需水量、适宜生态需水量和饱和生态需水量三种阈值模式的较为准确的计算方法，并从时空角度定量分析评价区域生态需水量和生态缺水量。结果表明，延安地区植被-土壤复合系统的年最小生态需水量为216.185亿m³，对应的年生态缺水量为23.556亿m³;重度生态缺水的景观类型有针阔混交林-壤土、针叶林-壤土和落阔叶林-粘壤土等，水量供需基本平衡的景观类型有灌草丛-粘壤土、灌丛林-粘壤土和草原-砂壤土等，轻度生态富水的景观类型有农作物-粘壤土、农作物-砂壤土和农作物-砂砾质壤土等;生态缺水较为明显的区域主要位于延安西南部和中部的黄土梁状丘陵沟谷区，时段集中在每年的夏秋两季。

Quantificational Analysis on Eco-water Requirement of Plant-Soil Compound Ecosystem Based on GIS:A Case Study of Yan'an Region in Northwest China

Although water has the central function of the bloodstream in the biosphere,especially in arid or semi-arid regions such as Yan'an region in Northwest China,yet very limited attention is paid to the role of the water-related processes in ecosystem.In this research,based on continuous 30-year weather condition report data and 10-year soil water content data in Yan'an region,using experiment models and field tests combined with GIS spatial analysis,a comparatively accurate method for measuring the minimum,moderate and maximum eco-water requirements of plant-soil compound ecosystem has been put forward.Additionally,the changing characters of eco-water requirement or scarcity have been addressed from spatio-temporal dimensions.The results show that:(1)The minimum eco-water requirement of plant-soil compound ecosystem in the study area is 21.6185 billion m3,and the corresponding scarcity is 2.3556 billion m3.(2)The landscapes presenting severe eco-water scarcity are conifer and broad-leaved mixed forest-loam,conifer-loam as well as deciduous and broad-leaved mixed forest-cohesive loam etc.The landscapes presenting eco-water budget balance are shrubby grass-cohesive loam,shrub-cohesive soil as well as grassland-sandy loam;and the landscapes presenting slight eco-water surplus are crop-cohesive loam,crop-sandy loam as well as crop-sand and gravel loam.(3)The areas with relative serious eco-water scarce problem are mainly located in the southwestern and central parts of Yan'an region on the hilly-gullied Loess Plateau,concentrating in summer or early autumn of the year.