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1、圣瓦肯河谷(San Joaquin Valley)西部灌区 位于加州南部圣瓦肯河和科思河流域的平原区,经过100多年的开发,已成为加州的主要农业区,在美国占有重要位置。这里降水少,蒸发大以及土壤和地下水中含盐,河谷东侧为山脉阻隔,自流水系自南向北汇流于旧金山入海,由于旧金山是美国大城市之一,受政治原因和环境保护制约,农田排除咸水的出路很难解决。灌溉水虽然含盐量小于350ppm,但大量灌溉水输入的盐量每年却超过160万t,在灌溉渗漏引起地下水位升高情况下,土壤盐碱化及生态环境的
1, San Joaquin Valley Western Irrigation District is located in the plains of the San Walcon River and Coos River Basin in southern California. After more than 100 years of development, it has become a major agricultural area in California and occupies an important position in the United States. Here less precipitation, evaporation and salt in the soil and groundwater, blocking the mountains to the east of the valley, the confluence of water flowing from south to north in San Francisco into the sea, because San Francisco is one of the major cities in the United States, subject to political reasons and environmental protection constraints, Farmland to exclude salt water outlet is difficult to solve. Irrigation water Although the salt content is less than 350ppm, the amount of salt input from a large amount of irrigation water exceeds 1.6 million tons per year. Under conditions of increased groundwater level caused by irrigation leakage, soil salinization and ecological environment