井灌井排对农田水盐分布的影响规律

Field Distribution of Water and Salinity under Well Drainage Combined Irrigation

为控制土壤次生盐渍化对灌区农业可持续发展的影响,探讨了井灌井排的控盐与水位降落效应及其对土壤水盐时空分布的影响。为此基于试验监测,先以渠灌为对照分析井灌井排及其与渠灌结合对区域水盐时空的改变,再剖析单井影响范围内的水盐时空变化规律及其影响机制。结果发现,井灌井排与渠灌结合可使地下水埋深控制在合理范围并使土壤剖面水盐含量维持在适宜作物生长的范围,三者均分别保持在1.6~5.0 m,10%~25%和300~500μS/cm的变化范围。在单井影响范围内,地下水埋深沿径向距离的增加而逐渐变浅,径向距离每增加100 m将减少0.35 m的地下水降落;土壤剖面含盐量随径向距离的增加而增加,其累积量与地下水埋深呈弱相关关系。井灌井排可维持灌区的水盐平衡与农业可持续发展,调整井距能缓解因地下水降落不均引起的远离井位区洗盐作用减弱的问题。

To alleviate the effect of soil secondary salinization on agricultural sustainable development,this paper explores the temporal and spatial distribution of soil water and salinity and topsoil salt accumulation under well drainage combined irrigation.The basin experiment is conducted to address the temporal and spatial distribution of soil water and salinity under the well drainage combined irrigation,canal irrigation and combined groundwater and surface water irrigation.The field experiment is implemented to analyze the temporal and spatial distribution of soil water and salinity along well radial distance.The appropriate groundwater depth and soil water content and salinity are maintained by the combined groundwater and surface water irrigation,and the groundwater depth and soil water content and salinity are 1.6~5.0 m,10%~25%and 300~500μS/cm respectively.Groundwater depth decreases along the well radial distance,and groundwater drawdown decreases by 0.35 m with the radial distance increase of 100 m.Soil profile salinity increases along well radial distance,and accumulated soil salts show a weak relationship with the groundwater depth.The well drainage combined irrigation has the potential to maintain the water and salinity balance and agricultural sustainable development,and reduced well spacing can attenuate salt accumulation because of salt leaching reduced by shallow groundwater depth far away from the well.