Abstract:

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 atmos-pheric 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: 1)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.

Key words: arid region, land surface process, MM5, numerical simulation, oasis