ZHANG Zhong-xue;WEI Yong-xia;KANG Bai-ying

;College of Water and Construction, Northeast Agricultural University, Harbin Heilongjiang 150030, PRC

wet and low-lying farmland;precipitation;surface water;soil water;ground water;converting measure

Most of China's wetland areas are located in Sanjiang Plain (Three River Basin). It's area has 207 X 104 hm~2 of wet and low-lying farmland, of which 59% is cropped. During 1970s and 1980s the Chinese government organized intensive scientific researchinto potential changes to existing natural resources conditions for this farmland The aim was to make the water resources regime beneficial to crop production. Arterial drainage field drainage and appropriate sub-soil treatments were suggested. The FourWaters converting mechanism and the estimation of the Four Water converting amount in wet and low-lying farmland were discussed in the paper.