Impact of rainfall structure and climate change on soil and groundwater salinization

Abstract

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.

Modelling the Impact on Root Water Uptake and Solute Return Flow of Different Drip Irrigation Regimes with Brackish Water

“…Note that leaching processes were most active within important events of rainfall that took place in September (from 25 to 30th cumulative rainfall = 63 mm) and December 2016 (from 7 to 9th cumulative rainfall = 226 mm with 153 mm recorded on the 8th). Slama et al [53] found that rainfall structure had a noticeable impact on the solute leaching processes. Also, in arid and semi-arid Tunisia, the impact of rainfall on soil desalinization was more important for coarse than fine soil texture irrigated with brackish water [54].…”

Convergency and Stability Responses of Bacterial Communities to Salinization in Arid and Semiarid Areas: Implications for Global Climate Change in Lake Ecosystems

“…As global climate change has intensified over the past several decades, arid and semiarid areas have been characterized by a negative moisture balance with evaporation exceeding precipitation ( Sered et al, 2011 ). Consequently, the decline in water volume has caused salinization to be the most concerning effect on lake ecosystems ( Slama et al, 2020 ; Ondrasek and Rengel, 2021 ). Concurrently, nutrient enrichment is also regarded as another most urgent environmental problem in arid and semiarid areas.…”

The Issue of Groundwater Salinization in Coastal Areas of the Mediterranean Region: A Review

“…In addition, in low lying areas, other parameters such as the subsidence rate have also been employed [235]. A similar approach was used by Benini et al [236] in which climatic balances using predicted climate scenarios were established to derive a vulnerability index to salinization, or by Slama et al [237], who analyzed the pattern of precipitations and evapotranspiration via an unsaturated model to predict soil and groundwater salinization patterns. While Sušnik et al [238] used an interdisciplinary approach to assess sea-level rise and CC impacts on the lower Nile delta, Egypt, where CC effects should be studied in light of all the previously available data, as suggested by Mabrouk et al [226].…”