七十年代以来,世界上许多国家的农田排水已有由明沟向暗管过渡的趋向。目前,暗管排水占排水面积的比例是:波兰为75%,捷克为70%,东德为50%,苏联为40%。西德每年铺设暗管约为百万亩,埃及和日本也有较大面积。近年来,我国江苏、浙江、山东、广东、上海等地暗管排水发展的也很快。 Since the 1970s, the drainage of farmland in many countries in the world has tended to transition from open ditch to open culvert. At present, the proportion of underground drainage to drainage area is 75% in Poland, 70% in the Czech Republic, 50% in the East Germany and 40% in the Soviet Union. The annual tube laying in West Germany is about one million mu, while Egypt and Japan also have larger areas. In recent years, China’s Jiangsu, Zhejiang, Shandong, Guangdong, Shanghai and other places to develop drainage is also very fast.