基于MIKESHE的流域表层土壤含水量时空变化特征分析

Spatial and Temporal Variation of Surface Soil Moisture Content Based on MIKESHE

基于气象站点实测资料、MODIS植被产品数据集LAI(leaf area index)及世界土壤数据库(HWSD)土壤数据,结合气象插值软件ANUSPLIN、土壤水分特征曲线拟合软件RETC、空间信息处理软件ArcGIS分别对气象、土壤、植被数据进行计算;使用MIKESHE分布式水文模型对拉萨河流域内2008-2017年3、7月及典型年(丰水年、中水年、枯水年)生长季(3-10月)内的表层1 m土壤含水量进行模拟。结果表明,在空间分布上,拉萨河流域表层土壤含水量自西南向东北呈递减趋势,流域中部拉萨河中上游的高山地区土壤含水量相对较低;相较于中下游河谷及西部盆地地区,中部高山地区土壤水分变化更为剧烈。在时间分布上,典型年生长季内不同月份土壤含水量变化量在33%~37%;总体而言,土壤含水量年内变化大于年际变化。拉萨河谷平原、澎波盆地、流域西部念青唐古拉山脉以东的洪积宽谷、羊八井盆地及流域东北部麦地卡湿地植被覆盖度和土壤水分含量较高、变化幅度小,农业适宜性较强。

Based on meteorological site data,MODIS vegetation product dataset LAI(leaf area index)and soil data of the world soil database(HWSD),soil moisture content in the March and July during 2008-1017 in Lhasa River Basin was simulated and analyzed by the MIKESHE model,a distributed hydrology model.The results showed that in the spatial distribution,the surface soil water content across the Lhasa River Basin gradually decreased from the southwest to northeast,and the water content in the alpine region on the east and west sides of the middle stream was lower.Compared with the valley locate in the middle-lower stream,the change of soil moisture in the central alpine area was more obvious.In terms of time distribution,the soil water content of the typical annual growth season changes in different months,varied between 33%and 37%;comparatively,the actual changes in soil moisture content were more obvious during the year.The basins and valley areas in the study area had higher vegetation coverage and higher soil moisture content,i.g.the Libo Basin and the Lhasa Valley Plain locate at middle-lower stream of Lhasa River,Hongji Kuangu and Yangbajing Basins in the east of the Nyainqentanglha Mountains in the western part of the basin,and the Medica wetland in the northeastern part of the basin.The resulting agricultural suitability is stronger in these areas.