根据80年代统计资料,全世界耕地面积为206亿亩,其中灌溉面积35.5亿亩,排水面积约24亿亩。美国排水面积最大,约9亿亩,其次为中国约3.3亿亩,苏联2.3亿亩,巴西在1亿亩左右。北美、南美和欧洲的排水面积比灌溉面积大。地处湿润区的欧洲,排水面积为灌溉面积的2.5倍,其中荷兰和芬兰,由于地理环境的特殊性,排水面积甚至超过耕地面积。 全世界大约有二分之一的土地,在不同程度上受到盐碱和渍涝的危害。一些地处干旱、半干旱地区的国家,都修建了大面积的的排水工程,如巴基斯坦和埃及,排水工程的面积分别达到耕地面积的20％和55％,并且还在进一步发展中。 20世纪以来,特别是第二次世界大战以后,农田排水得到广泛发展。近20多年来,农田排水技术也出现了下述的明显发展趋势: According to statistics from the 1980s, the world’s cultivated area is 20.6 billion mu, of which 3.55 billion mu is irrigated and the drainage area is about 2.4 billion mu. The largest drainage area in the United States is about 900 million mu, followed by China with some 330 million mu, the Soviet Union with 2.3 million mu, and Brazil with about 100 million mu. North America, South America and Europe have larger drainage areas than irrigated areas. Located in the wet zone of Europe, the drainage area of ​​2.5 times the irrigated area, of which the Netherlands and Finland, due to the special geographical environment, drainage area even beyond the arable land. About half of the world’s land is to some degree endangered by salinity and waterlogging. Some countries in the arid and semi-arid regions have constructed large-scale drainage projects such as Pakistan and Egypt, where drainage projects reach 20% and 55% of the arable land area, respectively, and are still under further development. Since the 20th century, especially after the Second World War, farmland drainage has been widely developed. The past 20 years, farmland drainage technology also appeared the following obvious trend: