西北干旱区滴灌数值模拟

土壤湿度的保持对作物生长非常重要。本文运用非静力平衡中尺度大气模式MM5,通过数值模拟的方式,分别从地气间水热交换和土壤湿度变化的角度,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: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·hm-2·(10d)-1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,水量过大不但造成水资源的浪费,而且对作物生长不利。500m3·hm-2·(10d)-1的灌溉水量仅为同期大水漫灌定额下限的一半和上限的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。

Numerical Simulation of Different Drip Irrigation Schemes for Oases of Arid Region in Northwest China

Soil moisture maintenance is very important for the plant growth in arid regions. For the hottest 10 days (July 21~31,2002), soil volumetric water content, sensitive and latent heat flux over oasis situated in the middle reaches of the Heihe River basin, were simulated for a range of drip irrigation schemes using the non-hydrostatic mesoscale atmospheric model MM5 with 1 km horizontal resolution. From the 10-day simulation, the following results were obtained that 500 m~(3)5hm~(-2) would be appropriate to maintain stable and sufficient soil moisture for oasis. A greater volume of irrigation water would not only waste water resources but also increase soil moisture to saturation levels, lower soil oxygenation and harm crops. While with lesser volume, evapotranspiration would exceed the water input, leading to drought conditions. Additionally, the 500 m~(3)5hm~(-2) water for July 21~31 is only half of the minimal quota and one-third of maximal quota for traditional irrigation over the same period. So drip irrigation is clearly a water-saving irrigation method, which could allow significant savings of the limited water resources in the arid region of Northwest China.