美国德克萨斯州高地平原区地下水灌溉管理方法研究

德克萨斯州高地平原区是美国灌溉和旱地作物的生产基地,其灌溉水源主要来源于奥加拉拉(Ogallala)地下水含水层。然而,自从1950年灌溉农业发展以来,由于对奥加拉拉含水层地下水的过度开采,使得区域地下水位严重下降,有些地区地下水位下降超过50 m。为了保护地下水资源和实现地下水可持续利用,2000年以来美国德克萨斯州高平原地区在节水压采方面开展了一系列工作,取得了较好的成效。采取的主要措施包括:用德克萨斯州高地平原蒸腾蒸发网络(The Texas High Plains Evapotranspiration Network, TXHPET)进行灌溉及地下水管理,改变作物品种,改进灌溉技术,改变种植结构,保护性耕作方法,加强降雨管理,将小部分灌溉农田转为旱作农田等。该区域1958年的灌溉面积为183万hm~2,1974年灌溉面积达到峰值,为242万hm~2;1989年灌溉面积降为159万hm~2,由于喷灌技术的推广应用,2000年灌溉面积恢复到187万hm~2。1958年大多数灌区为地面灌溉,仅有11%的灌溉面积为喷灌。1974年之后,灌溉总面积在减少,主要灌溉方式转为喷灌,中心支轴式喷灌面积稳步增长。自1989年之后,喷灌在该区域快速发展,2000年喷灌面积已占该区域灌溉面积的72%。早期的喷灌系统在较高压力下运行,自20世纪80年代,低压喷灌系统已全面使用。我国华北地区长期超量开采地下水与美国德克萨斯州高原区地下水超采情况及问题相似。兹系统介绍了美国德克萨斯州高地平原区在地下水超采情况下采取的综合措施拟为我国地下水超采地区的地下水管理工作提供技术与经验参考。

Groundwater Management in Texas High Plain

Texas High Plain is a major base for irrigated and dryland crops in USA. The main water source in the area is from the Ogallala Aquifer. However, since the development of irrigated agriculture in 1950, groundwater in the Ogallala Aquifer has been overused with groundwater tables dropped to 50 meters below the ground surface in some regions. To protect groundwater resources and achieve sustainable groundwater application, comprehensive technical and management measures have been taken over the past 15 years to alleviate detrimental impacts caused by groundwater overuse. The main measures taken included introduction of the Texas High Plains Evapotranspiration Network(TXHPET)for irrigation and groundwater management, increasing crop varieties and crop pattern, improving irrigation technologies, protection cultivation and rainfall management, and transforming some irrigated agriculture into rainfed agriculture. In 1958, the total irrigated area was 1 830 000 hm~2, and peaked at 2 420 000 hm~2 in 1974, followed by a reduction to 1 590 000 hm~2 in 1989 prior to recovering to 1 870 000 hm~2 in 2000 due to large-scale application of sprinkler irrigation. The main irrigation method in 1958 was surface irrigation, with only 11% of sprinkler irrigation area. Since 1974, the irrigated area has been reduced and the central pivot irrigation has been developed quickly. In 2000, about 72% of irrigated area was sprinkler-irrigated. The early sprinkler application was under high pressure, and low pressure sprinkler ushered in after 1980. As the north China plain is similar to the Texas High Plain, the experiences of Texas High Plain area could provide valuable help for groundwater management in north China.