西北内陆灌区土壤次生盐渍化与地下水动态调控

Secondary Salinification of Soil and Dynamic Control of Groundwater in Irrigation Area of Inland Basin, Northwestern China

土壤次生盐渍化其成因与地下水水位抬升存在密切关系。土壤次生盐渍化防治的根本措施是调控地下水位。本文在分析灌区土壤次生盐渍化发育特点的基础上,指出地下水临界深度不应是一成不变的,应该采用地下水动态临界深度。文中以天山北麓平原灌区为例,根据多年来土壤改良试验成果,确定灌区地下水临界深度为:解冻始2.0—2.5m,春灌始2.5—3.0m,春灌头水末1.2—1.5m,夏灌末2.0—2.5m,冬灌始2.5—3.0m,冬灌末1.3—1.5m。

Secondary salinification is one of the major eco-environmental problems in northwestern China, as its origin is in connection with groundwater level closely. The basic measure for prevention of the secondary salinification is to control the groundwater level. On the basis of analyzing the developing characteristics of the secondary salinification of soil in irrigation area, the present paper reviews that the critical depth of groundwater should be fixed value with neither spatial nor temporal change. In stead, it should adopt the dynamic critical depth of groundwater. The critical depth of groundwater has its own attributions of both space and period. According to the experimental achievements for soil restoration in the last years, this paper puts forward the different values of the dynamic critical depths of groundwater in the irrigation region located in the Northern Plain of Tian Mountain, namely the beginning of thawing, 2.0—2.5 m, the beginning of spring irrigation, 2.5—3.0 m, at the end of the first spring irrigation, 1.2—1.5 m, at the end of summer irrigation, 2.0—2.5m, at the beginning of winter irrigation, 2.5—3.0 m, and at the end of winter irrigation, 1.3—1.5 m, respectively.