RESEARCH ON THE RELATIONSHIPS BETWEEN ECO-DEPTH OF THEWATER TABLE AND ECOLOGICAL WATER REQUIREMENT INIRRIGATION AREA OFNORTHWESTERN CHINA

摘要

The relationships between eco-depth of the water table and ecological water requirement in irrigation area ofrnnorthwestern China is focused on in this paper. The concepts of groundwater ecological index and ecological safety index arerndiscussed and defined at first. Based on the relationship among water table depth, soil moisture, and ecological water requirement, arnnew mathematic expression of water table depth and ecological water requirement is built, which has been verified by field testsrnmade in Changji of Xinjiang, China. The eco-depths of water table for different crops (cotton, corn, winter wheat) in different soilrntypes are within the range of 1.3-2.3m, which tallies with the conclusion that the max groundwater table depth satisfying ecologicalrnwater requirement is less than 3m. The limit depths of water table for different soil types have been computed, with the average depthrnof 4.5m, which can tallied with the experiential value of 4.0~4.5m, and then the correctness of the derived formulas is proved.