地下水临界深度,是指表土含盐量在允许值以内时的地下水埋藏深度。一般作为改良盐碱土、防止土壤次生盐渍化,调控地下水位的重要指标以及排水工程设计的主要依据。以往确定地下水临界深度的经典方法是耕作层厚度加上土壤毛管水强烈上升高度。按此方法计算,灌区壤质土的地下水临界深度大于250厘米,粘质土的地下水临界深度 The critical depth of groundwater refers to the buried depth of groundwater when the amount of topsoil salinity is within the allowable value. Generally as a salinized alkaline soil to prevent secondary salinization of soil, the important indicator of regulation of groundwater level and the main basis for the design of drainage engineering. The classic method used to determine the critical depth of groundwater in the past is the tillage layer thickness plus the highly elevated height of the soil capillary water. Calculated according to this method, the critical depth of groundwater in the loamy soil in the irrigated area is more than 250 centimeters. The critical depth of groundwater in clay soil