The studied region is located in the southwestern Iran and on the border of Iran and Iraq. In the past, this region had dense palm groves and abundant plants. However, due to the decrease in upstream discharge, in recent years, saline and sodium seawater has intrusion in the river and affected the agricultural lands along its sides. This event has caused irreparable and serious damage to the agricultural industry in the region, turning this area into a graveyard of date palm trees. Understanding the characteristics of agricultural soils for their improvement and/or planting appropriate plants is one of the goals of sustainable agriculture. Considering the damage of the studied area from the intrusion of salt water in the Arvand River, this study investigated important characteristics of soil salinity including EC, pH, C.E.C, SAR and ESP. In this research, sampling of agricultural soils along the riverside was carried out in three different horizons and two line parallel to the river and at two different distances. Statistical methods of correlation coefficient, hierarchical analysis and factor analysis were used to identify the factors affecting soil quality and the relationships between parameters. The results showed that due to the intrusion of sodium seawater, the soils of the studied area have become saline-sodium, and the salinity level in the soils near the river mouth is higher than that in the soils on the upstream side of the river. In terms of fertility, the cation exchange capacity is in the medium range, and the clay texture and abundant organic matter of the soil as a result of the remaining plant and tree residues have an important effect on this parameter.

Coastal agriculture faces escalating threats from seawater intrusion (SWI), jeopardizing global food security through freshwater scarcity, soil salinization and crop damage. However, research on SWI often fails to consider its impact on coastal agriculture. Linking georeferenced SWI data with cropland presence, this review examines SWI's global distribution and primary drivers. Major attested hotspots include the Mediterranean, South and South-East Asia, and the Bohai Sea region in China. Approximately 87 Mha of cropland globally are vulnerable due to low elevation and coastal proximity, including regions where little to no literature has documented SWI. Main drivers include sea-level rise (SLR), drought, groundwater depletion, river modifications, tidal flooding and subsidence. Projections of SLR indicate cropland of North America, the Indian Subcontinent, and South-East Asia as high-risk for SWI. Additionally, regions like South-East Asia and the Indian Subcontinent are expected to experience significant demographic growth in coastal areas. Understanding present and future SWI dynamics is crucial for designing effective mitigation and adaptation strategies in coastal agriculture to support food supply.

A series of hydrogeologic framework model (HFM)-based steady- and transient-state numerical simulations is performed first using a coupled subsurface flow-transport numerical model to analyze groundwater flow and salt transport in an actual three-dimensional complex coastal aquifer system before and during groundwater pumping. A series of analytic hierarchy process (AHP)-based multi-criteria evaluations is then performed applying a multi-criteria decision-making approach to determine optimal pumping location and rate for a new pumping well in the complex coastal aquifer system during groundwater pumping. The complex coastal aquifer system is composed of six anisotropic fractured porous geologic media (five rock formations and one fault) and three isotropic porous geologic media (three soil formations) and shows high geometric irregularity and significant heterogeneity and anisotropy of the nine geologic media. Results of the steady-state numerical simulations show successful model calibration with 26 measured groundwater levels and two observed seawater intrusion front lines. The latter two are determined by spatial interpolation and extrapolation of electrical conductivity logging data and electrical resistivity survey data, respectively. Based on the status and prospect of necessary water uses and available groundwater resources, the field observations of groundwater and seawater intrusion, and the analyses of the steady-state numerical simulation after the model calibration, six candidate pumping locations are selected for the new pumping well. In addition, from six preliminary individual transient-state numerical simulations, maximum pumping rates at the six candidate pumping locations are calculated first, and a set of six incremental candidate pumping rates is then assigned at each of the six candidate pumping locations. Results of the transients-state numerical simulations show that groundwater flow and salt transport are spatially and temporally changed, and seawater intrusion is further intensified by groundwater pumping. In addition, the magnitudes of such spatial and temporal changes and intensification are significantly different depending on the candidate pumping locations and rates. Results of the steady- and transient-state numerical simulations also show that both complexity (geometric irregularity, heterogeneity, and anisotropy including the fault) and topography have significant effects on the spatial distributions and temporal changes of groundwater flow and salt transport in the coastal aquifer system before and during groundwater pumping. In addition, results of statistical estimations of the mesh Peclet and Courant numbers confirm acceptabilities of minimizing numerical dispersion in the steady- and transient-state numerical simulations. Based on the analyses of the transient-state numerical simulations, eight multiple criteria are chosen to judge, prioritize, and rank the six candidate pumping locations and six candidate pumping rates for optimal pumping. Results of the multi-criteria evaluations determine the optimal pumping location and rate for the new pumping well among the six candidate pumping locations and six candidate pumping rates. In addition, results of consistency checks confirm consistencies of judgments in the multi-criteria evaluations. Numerical simulations with successful model calibration show that spatial and temporal changes in groundwater flow and salt transport significantly depend on candidate pumping locations and rates Statistical estimations of the mesh Peclet and Courant numbers confirm acceptabilities of minimizing numerical dispersion in the numerical simulations Multi-criteria evaluations determine optimal pumping location and rate, and consistency checks confirm consistencies of judgments in the multi-criteria evaluations