灌溉在现代绿洲维持与发展中的重要作用

灌溉是荒漠绿洲农业发展的根本,没有灌溉就没有干旱区农业。本文运用美国NCAR的非静力平衡中尺度模式MM5V3,模拟了1991年8月1日到11日张掖绿洲地表感热、潜热通量和波文比,模拟结果表明此模式可以较好地反映张掖绿洲地表能量及水汽交换状况。同时模拟了当水源被截断后,地表感热、潜热通量及波文比随时间的变化:潜热迅速下降,感热迅速上升,波文比绝对值也迅速增大。如不及时补充水,绿洲将最终退化为沙漠。模拟结果证明了:①在我国西北干旱区有水才有绿洲,无水便成沙漠,水是绿洲的生命线,灌溉是现代绿洲维持与发展的基础;②绿洲一旦因缺水而退化为沙漠,就很难恢复。

Role of Irrigation in Maintenance and Development of Modern Oasis

Irrigation is the base of oasis agriculture. No irrigation no agriculture in desert. The sensible heat flux, latent heat flux and Bowen ratio of Zhangye oasis were simulated at 1~11 Aug 1991 using the non-hydrostatic mesoscale model MM5V3 of NCAR. The simulated results showed that this model could simulate the surface energy and water exchange of Zhangye oasis better. The sensible heat flux, latent heat flux and Bowen ratio of Zhangye oasis change with time were also simulated at 1~11 Aug 1991 without water providing. Results showed that the sensible heat flux higher, the latent heat flux lower; the absence of the Bowen larger, the time longer. Oasis will degenerate into desert at last if no irrigation in time. We can conclude that: (1) Oasis exists with water and desert without water. Water resource is the lifeline of oasis and irrigation is the base of its maintenance and development. (2) It is hard to reverse if oases turn to desert because of water lack.