黄河中上游地区的水汽再循环特征

Precipitation Recycling Characteristics of the Upper and Middle Yellow River Basin

为了深化对黄河流域水循环、水资源特性的认识并为黄河流域水资源保护和配置提供科学依据,采用WAM-2Layer水汽通量统计模型,基于1980—2018年ERA-5再分析数据集,对黄河中上游地区降水水汽来源和蒸散发水汽去向进行了分析,结果表明:黄河中上游地区降水内循环率和蒸散发内循环率的多年均值分别为10.3%和11.8%,水汽再循环对维持流域水资源安全、生态安全具有重要作用;黄河源区水汽内循环率远高于流域内其他地区,证实了黄河源区的双重"水塔"效应,即黄河源区既是稳定产流区也是流域降水的重要水汽来源区;黄河流域灌区用水量大,灌区蒸散发水汽再降水对流域水循环过程与空间格局有一定影响,河套灌区和青铜峡灌区蒸散发水汽在黄河中上游地区形成的再降水量占其蒸散发量的比例分别为3.0%和8.7%,落在我国陆地的比例分别为28.1%和34.7%,两灌区蒸散发水汽去向、内循环率因地形和气候因素的不同而具有明显差异,因此未来开展南水北调新增水资源优化配置、新扩建灌区等工作时应考虑新增蒸散发水汽的再降水因素。

Precipitation recycling,or water vapor recycling,is an important form of the renewal of water resources. In order to better understand the hydrological and water resources characteristics of the Yellow River Basin,as well as to provide scientific support to water resources protection and management decisions,this paper utilized the two-layer water accounting model(WAM-2 Layer)with the ERA-5 reanalysis data from year 1980 to 2018 to analyze the water vapor sources of precipitation and the re-precipitation of evapotranspiration in the upper and middle Yellow River Basin. Some conclusions have been obtained as follows. First,the water vapor recycling ratio within the basin is 10.3%for inner source of precipitation and 11.8% for re-precipitation of evapotranspiration,which reveals the importance of water vapor recycling in maintaining water resources and ecological safety. Second,the recycling ratio in the headwaters is much higher than that in any other regions within the basin,which proves the existence of the“water tower”effect,for both surface water resources and precipitation sources. Third,by comparing the re-precipitation of evapotranspiration from irrigation areas in the Yellow River Basin,i.e.,Hetao irrigation area and Qingtongxia irrigation area,it has been found that the re-precipitation of the two areas is 3.0% and 8.7% in the studied basin,and 28.1% and 34.7%in China's Mainland,respectively,mainly caused by their difference in geographical and climatological conditions. The results suggest that water vapor recycling should be considered in decision-making when water resources allocation and new irrigation areas are being planned.