美国加州中央河谷的南支圣荷坚河谷地区自70年代加州政府投资修建的北水南调工程使用以来,使这一地区的农业生产迅速发展,原来的戈壁沙漠地带,变成了大片良田和繁茂的果园。由于需由加州北水南调工程输送大量淡水淋洗改良盐碱地,同时需向外排出淋洗后的含盐水,使水资源不能得到有效充分的利用。近20年来当地农场主也日益感到究竟应该怎样处理大量的有盐的农田排水是极为困难的问题。根据论证分析,就地处理农田排水,使其符合灌溉水质标准,是当地合理利用水资源的有效途径。据估计到2000年每年将有近367000英亩一英尺(相当于4.53×10~8立米)的农田排水需加以处理。 Since the use of the North-South Water Transfer project, which was invested by the California government in the 1970s, the South Steward’s River Valley in the Central Valley of California has led to the rapid development of agricultural production in the region. The original Gobi Desert has become a large farmland and Lush orchard. Due to the need to deliver a large amount of freshwater leach to improve the saline-alkali land by the North South Water Transfer Project of California, at the same time, the leached saline water needs to be discharged to the outside so that the water resources can not be effectively and fully utilized. In the past 20 years, local farmers have also increasingly felt that it is extremely difficult to deal with the large amount of salty farmland drainage. According to the demonstration analysis, the on-site treatment of farmland drainage to make it comply with the irrigation water quality standards is an effective way for local rational utilization of water resources. It is estimated that by the year 2000 nearly 367,000 acres per foot (equivalent to 4.53 x 10-8 meters) of farmland drainage water will have to be treated.