摘要
西北地区全年水汽总输入为 1 0 61 9mm ,但只有 1 4 4%形成降水 ,85 6 %成为过境水汽直接穿过该地区上空出境 ,水汽净输入量仅为 31 1mm。西北地区降水分布很不均匀 ,内陆河地区多年平均降水量大于 30 0mm的都是高山带 ,而平原盆地的降水量多在 1 50mm以下 ,内陆河流域多年平均径流深仅有 6 8mm。西北水循环最突出的特点是径流系数小于蒸发系数 ,而干旱指数Ep/P (Ep:蒸发能力 ,P :降水 )十分大 ,介于 4～ 1 0之间。未来30年黄河及其以北地区气温平均升高 2 0℃ (HD模式 )或 2 38℃ (MPI模式 ) ,黄河以南地区气候平均升高 1 8℃ (HD模式 )或 1 5℃ (MPI模式 ) ,内陆河流域气温升高可能分别达到 3 1℃ (HD模式 )或 1 5℃ (MPI模式 )。据MPI模式结果 ,未来 30年黄河及其以北地区降水量平均增加 1 6 % ,而黄河以南地区降水量平均增加 1 1 4% ,干旱少雨的内陆河地区降水量可能减少 7%以上 ;黄河及内陆河地区的蒸发量将可能增大 1 5 %左右 ,西北区地表径流量的变化范围预计为 751～ 1 0 1 7亿m3。气候变化使得该地区天然径流减少 ,水资源供需矛盾将更加突出。
Annual water vapor import in Northwest China is about 1 061.9 mm, but only 14.4% becomes precipitation, while 85.6% flows out the region. As a result, the average runoff is only about 31.1 mm. Precipitation distribution is quite different from place to place in Northwest China. In inland river basins, annual precipitation more than 300 mm appears only in the high mountain areas. In most plain areas, however, annual precipitation is below 150 mm, and annual runoff is as low as 6.8 mm. The prominent feature of hydrological cycle in Northwest China is that most precipitation becomes vapor instead of runoff, and the drought ratio, Ep/P(Ep:evaporative power,P:precipitation), is as high as 4～10. According to GCMs outputs, to the northern part of the Yellow River, annual mean temperature will rise by 2.0℃(HD) or 2.38℃(MPI) by 2030, compared to 1.8℃(HD)or 1.5℃(MPI) to the southern part. In inland river basins, temperature will rise by 2.0℃(HD) or 2.38℃(MPI). In terms of the MPI simulations, annual mean precipitation will increase by 1.6% to the northern part of the Yellow River, 11.4% to the southern part, 7% in inland river basins. Annual mean evaporation in the Yellow River and inland river basins will increase by about 15%. Total streamflow in Northwest China will decrease by about (751～1017)×108 m3 under global warming scenarios, which indicates that water shortage would be severer in future in that region.
出处
《气候与环境研究》
CSCD
2003年第1期43-51,共9页
Climatic and Environmental Research
