Irrigated areas, mainly in arid regions, are threatened by salinization processes. Climate change inducing temperature rise and rainfall depletion are expected to enhance these processes. Numerical models are often used to predict salinization in the root zone as well as water and solute fluxes reaching groundwater. Climatic data, mainly rainfall, have an important influence on the estimation of those fluxes. The present paper studies the impact of rainfall structure and climate change on soil and groundwater salinization. Soil samples were collected in three drip-irrigated plots in Korba semi-arid coastal plain in Tunisia during dry and wet seasons. Collected field data (water contents and soil salinities) are used to define the initial solute and flow conditions and to estimate the soil hydraulic parameters for numerical modeling. Daily rainfall structure and annual rainfall transition under both Markov Chain and climate change (RCP4.5 and RCP8.5) are assessed. Different climatic scenarios are then introduced as boundary conditions in HYDRUS-1D, to test the influence of rainfall on the salinity evolution in the soil profile and groundwater. Results show that both annual rainfall amounts and daily structure have an impact on soil concentrations and solute fluxes quantities reaching groundwater. The influence of rainfall paths is more important for larger unsaturated zone thickness when considering the dry and median rainfall conditions. Climate change scenarios show significant accumulation of salts in the root zone implying the imperative use of adequate irrigation practices.

中文翻译：

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降雨结构和气候变化对土壤和地下水盐渍化的影响

灌溉地区，主要是干旱地区，受到盐渍化过程的威胁。气候变化引起的温度升高和降雨枯竭预计会加强这些过程。数值模型通常用于预测根区的盐渍化以及到达地下水的水和溶质通量。气候数据，主要是降雨量，对这些通量的估计有重要影响。本文研究了降雨结构和气候变化对土壤和地下水盐渍化的影响。在旱季和雨季期间，在突尼斯科尔巴半干旱沿海平原的三个滴灌区收集土壤样品。收集的现场数据（水含量和土壤盐度）用于定义初始溶质和流动条件，并估计数值建模的土壤水力参数。评估了马尔可夫链和气候变化（RCP4.5和RCP8.5）下的日降雨结构和年降雨转变。然后在 HYDRUS-1D 中引入不同的气候情景作为边界条件，以测试降雨对土壤剖面和地下水中盐度演变的影响。结果表明，年降雨量和日结构都对土壤浓度和到达地下水的溶质通量数量产生影响。在考虑干旱和中值降雨条件时，降雨路径的影响对于较大的非饱和带厚度更为重要。气候变化情景显示根区盐分大量积累，这意味着必须使用适当的灌溉方法。5 和 RCP8.5) 进行评估。然后在 HYDRUS-1D 中引入不同的气候情景作为边界条件，以测试降雨对土壤剖面和地下水中盐度演变的影响。结果表明，年降雨量和日结构都对土壤浓度和到达地下水的溶质通量数量产生影响。在考虑干旱和中值降雨条件时，降雨路径的影响对于较大的非饱和带厚度更为重要。气候变化情景显示根区盐分大量积累，这意味着必须使用适当的灌溉方法。5 和 RCP8.5) 进行评估。然后在 HYDRUS-1D 中引入不同的气候情景作为边界条件，以测试降雨对土壤剖面和地下水中盐度演变的影响。结果表明，年降雨量和日结构都对土壤浓度和到达地下水的溶质通量数量产生影响。在考虑干旱和中值降雨条件时，降雨路径的影响对于较大的非饱和带厚度更为重要。气候变化情景显示根区盐分大量积累，这意味着必须使用适当的灌溉方法。结果表明，年降雨量和日结构都对土壤浓度和到达地下水的溶质通量数量产生影响。在考虑干旱和中值降雨条件时，降雨路径的影响对于较大的非饱和带厚度更为重要。气候变化情景显示根区盐分大量积累，这意味着必须使用适当的灌溉方法。结果表明，年降雨量和日结构都对土壤浓度和到达地下水的溶质通量数量产生影响。在考虑干旱和中值降雨条件时，降雨路径的影响对于较大的非饱和带厚度更为重要。气候变化情景显示根区盐分大量积累，这意味着必须使用适当的灌溉方法。