水分胁迫对绿洲影响的数值模拟

Numerical Simulation of Environmental Influence Under Different Irrigation Volume in Arid Regions of NW China

运用耦合了包含土壤-植被-水文参数化陆面过程的非静力平衡中尺度大气模式MM5,将水平分辨率提高到1km,通过数值模拟的方式,分别从地气间水热交换、对绿洲小气候影响、土壤湿度变化以及径流量的角度,研究了2002年7月下旬我国西北干旱区绿洲环境在不同水量滴灌条件下的变化,从理论上找到了较适宜绿洲小气候维持的滴灌水量。结果表明:1、绿洲下垫面为农田时,从土壤保湿和绿洲小气候维持角度考虑,500m3/hm2/10天的滴灌水量对7月下旬黑河流域中游绿洲是一个比较合适的灌溉量。2、500 m3/hm2/10天的灌溉水量仅为同期大水漫灌定额下限的一半,上限的1/3,间接证明了滴灌是一种高效节水的灌溉方式,可以为干旱区节约大量水资源。

The environmental variations under different volume irrigation from 20 July to 30 July, 2002, were studied in the arid region of NW China based on the non-hydrostatic atmospheric mesoscale model MM5, in which the land surface process parameterization (OSU LSM) involving soil layers, vegetable layer and hydrological process was included. The horizontal resolution was selected as 1km. The influence on energy and water exchanges between land surface and atmosphere, atmospheric temperature and humidity at 2m height, soil moisture at four layers (10cm, 30cm, 60cm, 100cm depth ) and surface/underground runoff under different volume irrigation was analyzed. The proper volume maintaining the micro-climate of oasis was found out through analyzing. The following results were obtained: l)Accounting soil moisture conservation and the micro climate maintenance over oasis, 500m3 /hm2 drop irrigation for later dekad of July, 2002, is a proper volume in the middle reaches of HEIHE river basin if the land used is agriculture land. 2)The 500m3/hm2 /10d is just half of the minimum norm and one-third of maximum norm of flood irrigation. This conclusion proved indirectly that drop irrigation is a water saving and high quality irrigation method, which could hold the limited water resources massively in arid region of North -West China.