据联合国粮农组织1971年的报告:未衬砌灌溉渠道的渗漏损失很大,印度为18%～50%;在美国为33%～60%;在墨西哥为25%～60%,在孟加拉为50%.减少渠道渗漏损失的最有效的办法就是衬砌.衬砌的材料,有钢筋混凝土、素混凝土、水泥砂浆预制块、石料、砖以及沥青混凝土.它们虽然能满足防渗要求,但价格昂贵.有些国家使用廉价的材料 According to the 1971 report of the UN Food and Agriculture Organization (FAO), leakage from unlined irrigation channels is very high, with 18% to 50% in India, 33% to 60% in the United States, 25% to 60% in Mexico and 50% in Bangladesh %. The most effective way to reduce the loss of canal leakage is to lining the lining materials, reinforced concrete, plain concrete, cement mortar blocks, stone, brick and asphalt concrete. Some countries use cheap materials