雅鲁藏布江流域地-气系统的水平衡

Water Balance in Land-Atmospheric System over the Yalu Tsangpo River Basin

利用NCEP/NCAR 1 980 -1 989年 1 0年逐日 0 0UTC、 1 2UTC再分析资料及青藏高原降水、径流资料 ,研究了青藏高原雅鲁藏布江流域的水平衡特征 ,估算了雅鲁藏布江流域的蒸发、土壤和地下水含量。结果表明 :雅鲁藏布江流域夏季是水汽辐合区 ,降水大于蒸发 ;秋末到次年春季是水汽通量辐散区 ,蒸发大于降水。降水主要集中在 6～ 9月。径流的年际变化趋势同降水相近 ,径流主要是由降水补给的 ,径流峰值滞后降水峰值一个月。雅鲁藏布江流域土壤及地下含水量从 1～ 6月逐渐减少 ,7月以后开始增加 ,1 0月是土壤及地下水最丰富的时段。 2 0世纪 80年代中期和后期降水、蒸发、径流等呈增长趋势 ,这同ENSO事件有关。

The characteristics of water balance over Yalu Tsangpo River basin in Tibet are researched by using NCEP/NCAR twice daily (0000 and 1200UTC) reanalysis data, monthly runoff and precipitation for the period of 1980 - 1989, and the evaporation, soil and surface water storage are also estimated. The main results are as follows: (1) the Yalu Tsangpo River basin acts as a moisture sink from May through October, where precipitation exceeds evaporation, and as a moisture source during November-April, where evaporation exceeds precipitation; (2) in Yalu Tsangpo River basin, precipitation mainly occurs during summer, and runoff, whose peak value lags that of precipitation one month, cheifly supplied by precipitation; (3) the soil and subsurface water storage decreases from January to June, but increases after July and reaches its maximum in October; and (4) over Yalu Tsangpo River basin there are raising trends in precipitation, evaporation, and runoff in late 1980s, which are related to ENSO events.