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根据多年生产实践与科学实践资料,按照农业发展对灌溉排水的不同要求,我们的地域可划分为常年灌溉带、不稳定灌溉带和补充灌溉带 1、常年灌溉带 年降水量小于400mm的地带,主要包括西北内陆和黄河中游部分地区。在这一地带,由于年降水总量和各季节的降水分配,都难以满足农作物正常生育的需要,灌溉需要指数(即灌溉水量占农作物总需水量的比值)一般均大于50～60％。常年灌溉是农业发展的必要条件。排水则是由于灌溉引起的要求,包括降低灌区地下水
According to years of production practice and scientific practice, according to the different requirements of irrigation and drainage for agricultural development, our region can be divided into perennial irrigated zone, unstable irrigated zone and supplementary irrigated zone. 1, Annual irrigated zone with annual precipitation less than 400 mm, Mainly include the inland northwest and parts of the middle reaches of the Yellow River. In this area, the annual total precipitation and the seasonal distribution of precipitation are difficult to meet the needs of normal crop growth. The index of irrigation needs (ie, the ratio of irrigation water to the total crop water demand) is generally more than 50-60%. Perennial irrigation is a necessary condition for agricultural development. Drainage is due to irrigation requirements, including reducing irrigation groundwater