Salinization Of Groundwater Resources Research Articles

Using TODIM decision method to control saltwater intrusion by numerical simulation approach (study area: Nowshahr-Nur aquifer)

Over-pumping of aquifers and lack of planning for the water resources, and allocation system in coastal aquifers, in addition to minor problems, disturb the ecological balance. This type of exploitation reduces the groundwater level and the hydraulic gradient in the coastal strip and, due to the higher density of saline water, includes the invasion of saline water and salinization of groundwater resources. Due to population growth, migration, drought, and over-pumping in the southern part of the Caspian Sea, this issue has disturbed the balance of groundwater resources, and most of the coastline has been associated with increasing solute concentrations. Accordingly, in this study, using the SEAWAT code, the intrusion of saltwater in the Nowshahr-Nur aquifer has been simulated, and the results analyzed, which showed that in the current situation, saline water intrusion spreads a wide width of 862 m from the aquifer. To control the current situation of saline water invasion in the coastal strip, seven treatment strategies were simulated and the TODIM decision-making method was used to prioritize. For this purpose, four criteria of economic, social, environmental, and groundwater level improvement were selected for decision-making and weighed by hierarchical analysis. The weighting results showed that the criterion for improving the groundwater level with a weight of 0.311 is the most important. Based on the weighting of the criteria, the strategies were prioritized and the results showed that a 20% reduction in aquifer abstraction by combining the construction of an underground barrier was selected as a solution to control the invasion of short water. The results of this solution showed that 317 m of saline water backflow will arise in the Nowshahr-Nur aquifer.

Characterization of groundwater in the arid Zenaga plain: Hydrochemical and environmental isotopes approaches

The Zenaga inlier, located in an arid area in southeastern Morocco, is mostly characterized by igneous and metamorphic fractured rocks. The surface water is quasi-absent and local populations (95% rural) are entirely dependent on groundwater resources for drinking and irrigation purposes. To evaluate the main factors controlling the origin and salinization of groundwater resources, we have investigated the chemical and stable isotope compositions of 23 groundwater samples. In addition, water quality assessment parameters including sodium absorption ratio (SAR) and water quality index (WQI) were also calculated. The results show that the majority of wells and boreholes are characterized calcium bicarbonate water type (78% of samples), with the following ionic sequence Ca2+>Na+ >Mg2+ >K+, and HCO3−> Cl−>SO42−>NO3− for cations and anions, respectively. A significant enrichment on major ions is steadily rising with depth as the water type changes toward calcium chloride. The interpretation of hydrochemical data suggests that the silicate weathering, cation exchange and evaporites dissolution are responsible for the groundwater chemistry. The majority of water samples are good to permissible for irrigation and poor to good for drinking purposes. The mineral salts found at greater depths degrade groundwater quality. In some areas, nitrate contents imply anthropogenic contamination derived especially from traditional septic tanks. Stable isotopes δ18O and δ2H reveal a distinction between the shallow aquifer and deep circulations. The uncommon depleted isotope signature found in deep circulations was associated with cold altitudes recharge, whereas the heaviest groundwater observed in shallow aquifer was interpreted as the contribution of surface water from Taghdout Dam. The Anti-Atlas Mountains and Siroua Massif's high altitude served as a source of recharge. The mixing at considerable depths and along the groundwater path appears to decrease the isotopic variability in the shallow and deep groundwater.

An investigation of the source of salinity in groundwater using stable isotope tracers and GIS: A case study of the Urmia Lake basin, Iran

Salinization of groundwater resources, especially in arid areas, limits their use. This problem can be aggravated by low annual precipitation, greater evaporation, and an excessive water discharge. The various sources of salinization, particularly in the unconfined aquifers, make it difficult to manage these resources. The sources of salinity can be detected through detailed sets of tracer data and a spatial analysis of their variation over the aquifer. Regarding the intense computational effort needed for this purpose, the geographic information system (GIS) can be used as a powerful tool for spatial analysis. This study aims to reveal the sources of salinity in the Azarshahr and Shabestar-Sufyan aquifers located in the Urmia basin, northwest Iran. The study is based on a comprehensive geochemical and stable water isotope (δ18O, δ2H) investigation of groundwater. We conclude the effectiveness of using isotope tracers to observe the effect of basin geology on water salinity. Evaporation and the dissolution of evaporative rocks in these regions is greatly effective in the isotopic concentrations. As is evident from a Piper diagram, in some parts of the study area, the main groundwater source is precipitation and there is no significant relationship between precipitation and the Urmia Lake.

Elucidating the sources and mechanisms of groundwater salinization in the Ziz Basin of southeastern Morocco

In the Ziz Basin, located in arid area in southeastern Morocco, surface waters are scarce and local populations are entirely dependent on groundwater resources for drinking and irrigation. In order to evaluate the main factors controlling the origin and salinization of groundwater resources, we have investigated the chemical and stable isotope compositions of groundwater and surface water in different areas in the Ziz basin, upstream and downstream from the Hassan Addakhil dam, which is the major man-made reservoir in the basin. A large variation in water quality was observed, specifically an increase in salinity from north (upstream to the reservoir with TDS ~ 460 mg/L) to south (downstream; TDS ~ 16,000 mg/L). In the northern portion of the basin, the low saline groundwater is composed primarily of Ca2+ and Mg2+ due to dissolution of carbonate formations in the High Atlas Mountains. In contrast, the major dissolved consequents of saline waters are Cl−, SO4 2− and Na+, apparently due to dissolution of evaporite minerals (gypsum and halite). In some areas elevated nitrate contents imply anthropogenic contamination derived from local agriculture. The stable isotopes data (δ18O = −8.6 to −8.3 ‰ and δ2H = −55.7 to −53.8 ‰) indicate that the High Atlas Mountains, upstream of the reservoir constitute the major source of water to the Ziz Basin. Given that this arid basin is entirely dependent on groundwater resources, long-term salinization of groundwater in the Ziz Basin could lead to negative effects and reduction of the local agricultural productivity in addition to the degradation of drinking water quality in this region.

Seawater intrusion and coastal groundwater resources management. Examples from two Mediterranean regions: Catalonia and Sardinia

Seawater intrusion is a natural phenomenon that allows the encroachment of saline water into aquifers. Nevertheless, many human actions along the coastline, in particular groundwater withdrawal, enhance this process and finally cause the salinization of groundwater resources. Here we review the hydrogeological basis of seawater intrusion and describe specific cases in Catalonia and Sardinia, as examples of environmental problems and water management actions. We emphasize the origin of salinization and the hydrogeological details of each case, as well as the solutions that have been implemented to prevent groundwater salinization. [Contrib Sci 10:171-184 (2014)]

Water and salt balance at irrigation scheme scale: A comprehensive approach for salinity assessment in a Saharan oasis

Salt balance methods are generally applied in the root-zone and at local scales but do not provide relevant information for salinity management at irrigation scheme scales, where there are methodological impediments. A simple salt balance model was developed at irrigation scheme and yearly time scales and applied in Fatnassa oasis (Nefzaoua, Tunisia). It accounts for input by irrigation, export by drainage and groundwater flow, and provides novel computation of the influence of biogeochemical processes and variations in the resident amount of salt for each chemical component in the soil and shallow groundwater. Impediments were overcome by limiting the depth of the system so that the resident amount of salt that remained was of the same order of magnitude as salt inputs and allowed indirect and reliable estimation of groundwater flow. Sensitivity analyses as partial derivatives of groundwater salinity were carried out according to non-reactive salt balance under steady-state assumption. These analyses enabled the magnitude of the salinization process to be foreseen as a function of hydrological changes linked to irrigation, drainage, groundwater flow and extension of the irrigated area. From a salt input of 39 Mg ha −1 year −1 by irrigation, 21 Mg ha −1 year −1 (54%) and 10 Mg ha −1 year −1 (26%) were exported by groundwater flow and drainage, respectively. 7 Mg ha −1 year −1 (18%) were removed from groundwater by geochemical processes, while a non-significant 2 Mg ha −1 year −1 were estimated to have been stored in the soil and shallow groundwater where the residence time was only 2.7 years. The leaching efficiency of drainage was estimated at 0.77. With a water supply of 1360 mm by irrigation and 90 mm by rainfall, drainage, groundwater flow and actual evapotranspiration were 130, 230, and 1090 mm, respectively. The current extension of date palm plantations and salinization of groundwater resources are expected to significantly increase the salinity hazard while the degradation of the drainage system is expected to be of lesser impact. The approach was successfully implemented in Fatnassa oasis and proved to be particularly relevant in small or medium irrigation schemes where groundwater fluxes are significant.

Sea-level trends and physical consequences: applications to the U.S. shore

As our knowledge of the potential for future global warming increases, our understanding of the imminent dangers associated with continued, possibly accelerated, sea-level rise increases. Several independent research groups have predicted future sea-level rise on the order of 15 to 50 cm by the middle of next century, and between 30 and 110 cm by 2100. Considering the concentration of coastal populations, and dollar value of industries and developments, these increases in mean sea level pose significant hazards. A linkage exists between sea-level history and climate history, but research has demonstrated that sea level is controlled by a complex interaction of geologic, hydrologic and climatologic factors. Because of insufficient data describing global-scale hydrological phenomena, we lack understanding of the components of sea-level change. Present estimates of the various contributions to trends in sea level do not agree with physical measurements of sea-level history. This hampers our ability to make accurate predictions of sea-level behavior. Sea-level rise implies the future threat of accelerated coastal erosion, increased frequency and severity of structural damage resulting from storms which make landfall, salinization of groundwater resources and estuarine and other aquatic ecosystems, destruction of coastal wetlands leading to severe impacts on coastal marine biologic communities, and significant damage to the infrastructure of coastal cities and other population centers. Federally sponsored study groups have completed a series of specific recommendations dealing with the threat of sea-level rise and appropriate responses by parties concerned with the coastal zone. These describe a policy of planned retreat from the coast on a schedule dictated by natural events and processes. The Federal Emergency Management Agency would delineate coastal hazard zones and provide appropriate planning policies governing future development. Compliance with hazard zone standards would determine landowner participation in the National Flood Insurance Program. Federal, state, local and private interests in coastal lands should respond to the threat of sea-level rise and coastal erosion with innovative land management policies and practices that encourage the establishment of coastal high-risk zones and conversion of these lands to low-risk usage.