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合理利用微咸水灌溉对缓解淡水紧缺有重要意义。为评价漫灌对微咸水膜下滴灌棉田地表以下0~60 cm深度积盐的淋洗效应,2013年漫灌前、后采用EM38-MK2型电磁感应仪进行大地表观电导率(ECa)调查,通过取样率定得出对应盐分解译模型。将解译获得的漫灌前、后土壤含盐率作为区域化变量,经K-S检验为正态分布,并分别服从指数和球状半方差函数模型。变程相近而基台值远大于灌前,表明灌后变异程度增强。Kriging插值结果显示,实际不合理的漫灌方式,使得灌后土壤返盐,0~60 cm深度范围积盐增量达4.1×104kg/hm2。利用HYDRUS-1D建立土壤水盐运移模型模拟优化的灌水定额为360 mm,较实际灌水定额615 mm节水255 mm,脱盐率为39.3%。持续微咸水灌溉需要完善的农田排水、排盐渠系和盐分排泄区。
Reasonable use of brackish water irrigation is very important to alleviate the shortage of fresh water. In order to evaluate the leaching effect of flood irrigation on salt accumulation in the depth of 0 ~ 60 cm below the subsurface drip irrigation with brackish water, the surface apparent conductivity (ECa) was measured by EM38-MK2 electromagnetic induction before and after flood irrigation in 2013, Through the sampling rate to determine the corresponding salt decomposition model. The soil salinity before and after flooding was interpreted as a regionalized variable by the K-S test, and was normalized by K-S test and obeyed the exponential and spherical semivariance function models respectively. Similar to the variation of the substratum and abutment value is much larger than irrigation, indicating that the degree of variation after irrigation increased. The results of Kriging interpolation show that the unreasonable flood irrigation mode makes the soil salt return after irrigation, and the increment of salt accumulation in the depth of 0 ~ 60 cm reaches 4.1 × 104 kg / hm2. Using HYDRUS-1D to establish the soil water and salt transport model, the optimized irrigation standard was 360 mm, which was 255 mm lower than the actual irrigation standard of 615 mm and the desalination rate was 39.3%. Sustained brackish water irrigation needs well-established farmland drainage, drainage canal systems and salinity drainage areas.