延安市河流系统生态环境需水量测评与分析

Quantificational analysis in ecological water requirement of plant-soil compound ecosystem in Yan'an city based on GIS

根据延安市主要水文站点近50 a的径流量、输沙量等实测资料和各污染站点近10 a的水质分析资料,以区域河流系统为研究对象,提出了基于GIS空间分析的河流生态环境需水量的测算方法,定量对比分析区域河流系统的生态环境需水量及其时空分布特征,明确主要流域生态需水和经济用水的理论阈值,为区域河流系统各项生态环境需水的平衡以及生态用水和经济用水的优化配置提供科学有据的参考.研究结果表明:延安市主要河流系统的生态环境需水总量为10.619亿m3,建议地表水的经济取用总量为2.445亿m3;河流系统的输沙需水量决定了综合生态环境需水总量,汛期输沙需水量显著高于基本生态需水量和自净需水量,占到全年需水总量的80%以上;20世纪50—70年代主要河流的输沙需水量相对偏高,20世纪80—90年代,输沙需水量整体呈明显下降趋势.

Based on the past 50 a data about runoff volume, sediment discharge as well as sediment accretion from hydrographic stations, and 10 a data about water quality from pollution stations, a method for measuring the instream flow requirement supported by experiential models and GIS spatial analysis was put forward. Additionally, the changes characters of instream flow requirement for ecological environment and economic development have been addressed from spatial--temporal dimensions. The results showed that the ecological water requiement of the main river systems in Yan＇an region reached to 1. 0619 billion ms , the surface water for economic exploitation was 0. 244 5 billion ms ; the instream flow requirement for sediment transportation determined the integrated ecological water requirement; the water need for sediment transportation in flood season occupied over 80% of that in all year, which indicated the runoff volume is larger and sediment transport competency is higher in flood season; the instream flow requirement for sediment transportation from 1950s to 1970s was comparatively higher, and the requirement from 1980s to 1990s presented a decreasing tendency, which accounted for environment in study area had been improved gradually and sediment in rivers was reduced obviously.