若尔盖湿地水源涵养时空变化及影响因素

Spatiotemporal Variation of Water Conservation and Its Influencing Factors in ZoigêWetland

若尔盖湿地是黄河重要的水源涵养地。研究若尔盖湿地水源涵养量时空变化特征,提出水源涵养率指标并用于分析水源涵养能力变化,对于丰富生态系统水源涵养评估研究、科学布局若尔盖湿地生态保护和建设工程具有重要意义。选取四川省若尔盖湿地为研究区,利用水土评价模型(soil and water assessment tool,SWAT)构建了涵盖研究区的流域分布式水文模型,计算分析了1971—2016年湿地水源涵养量及其时空变化特征,基于水源涵养率指标分析了若尔盖湿地水源涵养能力及其变化,并探讨了其影响因素。结果表明:若尔盖湿地年水源涵养量为121.4~348.1 mm,20世纪90年代开始明显减少,黑河流域减少尤为显著;水源涵养率总体呈减小趋势,年均水源涵养率由1971—1995年的0.34减小到1996—2016年的0.30,90年代中期以来若尔盖湿地水源涵养能力明显下降;潜在蒸散发量增加、主要水源涵养植被土地面积减小等气候变化和土地利用变化是若尔盖湿地水源涵养量减小及功能降低的重要影响因素。

The Zoigêwetland is an important water conservation area of Yellow River.To study the spatiotemporal variation characteristics of water conservation amount in Zoigêwetland and analyze the change of water conservation capacity based on the proposed water conservation rate index is of great significance to enrich the evaluation of ecosystem water conservation and scientifically arrange the ecological protection and construction project of Zoigêwetland.The Zoigêwetland in Sichuan Province was selected as the study area.Based on soil and water assessment tool(SWAT),the distributed hydrological model covering the study area was built to calculate and analyze the water conservation and water conservation capacity of the wetland from 1971 to 2016,its change and the influencing factors of the changes were discussed.The results show that the annual water conservation of Zoigêwetland is 121.4~348.1 mm,which began to decrease significantly in the 1990 s,especially in Hei River Basin.The average annual water conservation rate decreases from 0.34 in 1971-1995 to 0.30 in 1996-2016.Since the mid-1990 s,the water conservation capacity of Zoigêwetland has decreased significantly.Climate change and land use change,such as the increase of potential evapotranspiration and the decrease of main water conservation vegetation area,are the important influencing factors for the decrease of water conservation and function in Zoigêwetland.