基于Modflow-Hydrus耦合模型的改良盐碱土水平井排水效果分析

为了提高盐碱土改良水平,确定科学合理的灌排工程设计方案,建立饱和-非饱和土壤水分运移Modflow-Hydrus耦合模型,对试验区不同情景水平井的排水效果进行模拟分析.结果表明:当地下水位埋深较小时,季节变化对地下水综合补给强度有明显影响,当地下水位埋深大于6 m,不同时段地下水综合补给强度均趋于常数,当地下水位埋深较大时,通过厚层包气带的降水补给均匀;断续排水时单个水平井400 m控制范围内,潜水位显著下降,具有良好的疏干效果,降深与水平井的年抽水强度成正相关;天然环境条件下,区内降水入渗补给和潜水蒸发保持平衡,以试验区中心向外扩展,排水试验有效改善8倍试验区面积范围内降水入渗-潜水蒸发环境,使包气带土壤水分进入饱水带,潜水水位呈下降趋势.研究成果为盐碱土壤改良的水平井施工设计提供理论参考.

Analysis of horizontal drainage well effect of saline-alkali soil amelioration based on Modflow-Hydrus coupling model

In order to improve the amelioration level of saline-alkali soil,and determine the scientific and reasonable design scheme of irrigation and drainage engineering,the Modflow-Hydrus coupling model of saturated-unsaturated soil water transport was established,and the drainage effect of horizontal wells in different scenarios in the test area was simulated and analyzed.The results show that:when the depth of groundwater level is shallow,the seasonal variation has an obvious influence on the comprehensive recharge intensity of groundwater;when the groundwater depth is greater than 6 m,the comprehensive recharge intensity of groundwater tends to be constant in different periods;when the groundwater depth level is large,the precipitation supply through the thick vadose zone is uniform.When intermittent drainage occurs,the phreatic water level of a single horizontal well decreases significantly within the control range of 400 m,which has a good drainage effect.The drawdown is positively correlated with the annual pumping intensity of horizontal wells.Under the natural environment,the precipitation infiltration and phreatic water evaporation keep balance,and extend outward from the center of the test area.The drainage test can effectively improve the precipitation infiltration and phreatic evaporation environment within 8 times of the experimental area,so that the soil moisture in the vadose zone enters the saturated zone,and the phreatic water level shown a downward trend.The research results provide theoretical re-ference for horizontal well construction design of saline-alkali soil improvement.