Salty Water Intrusion Research Articles

Climate Change Vulnerability Assessment. A Framework for Urban Planning Practitioners in Ilala District, Dar es Salaam City, Tanzania.

Global climate change is a challenge undisputable in the intervening time. The Global South countries are the most vulnerable to global climate change. It is indicated by the prevalence of climate hazards including extreme temperatures leading to urban heat island effects(UHI, prolonged droughts, melting of ice caps, increased extreme weather events such as tropical cyclones, heat waves, urban flooding, sea level rise, and coastal erosion resulting in salty water intrusion into freshwater aquifers. This paper explores a framework for climate change vulnerability assessment in the urban planning process in cities of the Global South. A sample of 95 households was selected purposely for study. Data collection methods involved interviews by structured questionnaires, surveys, focused group discussions, observations, and documentary reviews. Quantitative data analysis was done using a statistical package for social sciences. Qualitative data were analysed by content analysis, narrative analysis, and interpretive phenomenological analysis. Results showed that climate change physical infrastructures, socioeconomic activities and livelihoods and ecosystems were vulnerable to climate change-induced flooding in urban areas. The study concludes that adoption of new urban planning process enhances resilience and sustainable cities and communities in cities of the Global South.

Review of the current state of technology for capacitive deionization of aqueous salt solutions

The availability of clean water at affordable prices is one of the key technological, social, and economic challenges of the 21st century. The increased extraction of groundwater worldwide is leading to the gradual intrusion of salty water into sources and water horizons. In order to use this water for industrial and agricultural purposes, or as drinking water, it needs to be purified and desalinated. Thus, methods of desalinating water of different salinity levels, ranging from brackish to seawater, are becoming more prominent. The overall goal of current research is to make water desalination technologies more energyefficient and cost-effective. One promising technology that meets these requirements is capacitive deionization (CDI) of water. This technology has been widely known for over 30 years, but significant progress in CDI research has only been achieved in recent years. In this review, we examine the currently developed architectures of CDI cells, advancements in carbon materials, and discuss the prospects and challenges of commercializing this technology.

Hydrodynamic Behaviors and Geochemical Evolution of Groundwater for Irrigation in Yaoba Oasis, China

The Yaoba Oasis is an irrigated cropland entirely dependent on groundwater; previous investigations (1980–2015) revealed an over-abstraction of groundwater and deteriorating groundwater quality. For further exploring the hydrodynamic behaviors and geochemical processes of groundwater during the irrigation season, groundwater samples were collected and analyzed using different techniques including classical statistics, correlation analysis, Piper diagrams, and Gibbs diagrams. The results indicated that Na+, K+, SO42− and Cl− were the main ions in groundwater, which were significantly correlated with TDS. The water–rock interaction is manifested by the precipitation of calcite and dolomite and the dissolution of rock salt and gypsum as an increase in TDS related to evaporation. In addition, the increasing complexity of hydrochemical type is caused by the rapid variation of hydrodynamic regime, irrigation and evaporation, which are subjected to the constraints of salty water intrusion from the desert salty lake and infiltration of irrigation return flow. Existing wells should limit overexploitation to halt the decline in groundwater levels and cut down irrigation water to reduce the risk of groundwater contamination and restore ecological balance in desert oasis.

Groundwater Vulnerability Analysis via GALDIT-GIS Method to Seawater Intrusion, South of Iraq

One of the most significant environmental problem that needed to be identified and managed is the intrusion of salty water into the aquifers. Human actions, such as excessive irrigation pumping, as well as the rising sea level, have generated a vulnerable state for seawater intrusion into aquifers. Six effective factors have been focused on evaluating seawater intrusion of groundwater Dibdibba aquifer in Basrah, south of Iraq mainly based on the GALDIT-GIS model involving the groundwater occurrence, aquifer hydraulic conductivity, groundwater levels above sea level, distance to shoreline, impact the existing status of seawater intrusion, and thickness of the aquifer. Water samples were collected for 19 wells over the area concerned. Chemical parameters including SO₄²ˉ, Clˉ, and Total Dissolved Solids were applied for modeling in addition to measuring depth to groundwater level. The results of the GALDIT model showed that the Dibdibba aquifer revealed three levels of vulnerabilities arranged according to risks: a high level which occupied Umm Qasr area and the near distance of Khor Al-Zubair to shoreline with an area of 76.87 Km² and 82.56 Km², moderate level represented the long distance of Khor Al-Zubair to shoreline and Safwan areas about 205.21Km² and 196.61 Km², and low level represented Al-Muwailihat area with 139.65Km² and 142.61 Km² for the wet and dry season, respectively.

Long-term changes in water mineral concentrations and their influence on sediment water content in a shallow lake

During the last four decades, substantial changes have been observed not only in tripton concentrations but also in other limnological parameters in Lake Kasumigaura, a shallow eutrophic lake. A previous study reported that tripton concentration showed a positive correlation with sediment water content (WC) and a negative one with sediment ignition loss. To explain the changes in sediment WC, we conducted an analysis of the changes in mineral concentrations and sediment WC during 1979–2016 to determine their relationship. High mineral concentrations in water throughout the lake were observed in the latter half of the 1990s and higher WC in sediments followed with a time lag of a few years, resulting in significant correlations. The relationship between them was confirmed in laboratory experiments that indicated swelling of sediments (slowdown of sediment compaction) by the addition of NaCl into the water-sediment system. In contrast, significantly lower SS concentrations in overlying waters observed in higher mineral conditions were similar to previous studies. The significantly low annual precipitation during 1994–1997 probably caused high Na+ and Cl- concentrations in the lake waters in the latter half of the 1990s. The combined influence of sea-spray aerosol and evaporation was suspected to be the cause of high salt concentrations. The intrusion of salty water through the downstream gate and/or surrounding construction structures was another possibility.

Simulation and Evaluation of a Hybrid Renewable Energy System for Supplying a Desalination Unit on the Island of Lipsi, Greece

Water scarcity is a serious problem for the Aegean Islands in Greece. Due to the fact that tourist development grows in a continuous way, the situation has deteriorated over the last years. Current water resources management practices involving the exploitation of the groundwater reservoirs have provoked the salty water intrusion into the aquifers and in many arid islands water is transported by sea, at a considerably high cost (reaches about 12 €/m³ in some cases). Desalination is foreseen as a solution to this problem and it has already been adopted in many islands, as it is a process that can provide fresh and potable water in the required quantities, at a much lower cost. The coupling of desalination with renewable energy sources (RES) constitutes an appealing and promising option. This paper presents an integrated case study regarding the design and operation of a water-energy system for meeting irrigation and potable water demand in Lipsi Island (Dodecanese complex, Greece). As the desalination unit operation depends on the wind power, a detailed description regarding the generation of synthetic time series of wind speed data is also presented. Finally, a Cost-Benefit Analysis is carried out to discuss each scenario we examine from a financial perspective.

Review on the role of geoelectrical surveys in characterizing and deriving the constraints and hydrogeological conditions in semi arid Khanasser Valley region in Syria

Abstract This paper is a general review which basically focuses on the role of geoelectrical surveys in characterizing and deriving the constraints and hydrogeological conditions in semi arid Khanasser valley region and its surroundings in Northern Syria. Schlumberger configuration has been used to carry out ninety six vertical electrical soundings VES, distributed on nine transverse and three longitudinal profiles. Their quantitative 1D interpretations with different techniques yield to develop several alternative approaches, that enable us to derive and determine the hydrological parameters of the structures controlled by the groundwater distributions. Two different northern and southern geological structures separated by Hobs-Serdah water divided line were electrically characterized. Both of them are of very conductive zones of a resistivity less than 4 Ωm, and related to the intrusion of salty water in Quaternary and Paleogene aquifers. The qualitative interpretation of the iso-apparent resistivity maps for different AB/2 spacings has allowed the delineation of those two structures. Those two identified structures have their evident influences on the distributions of thicknesses, resistivity, salinity, hydraulic conductivity, and transmissivity of both Quaternary and Paleogene aquifers. The high resistivity exceeding 300 Ωm on the measured VES is a very good signal of the presence of basalt formation of upper Miocene age in Jebel Al Hass in the west and Jebel Shbith in the east. The geometry and the electrical characteristics of Quaternary and Paleogene aquifers and the top of Maestrichtian have been well recognized. Quaternary paleosabkhas, fractured zones and tectonic features of the subsurface of Khanasser valley have been delineated through analyzing VES distributions along the executed longitudinal and transverse profiles. Different empirical relationships have been already established through coupling geoelectrical resistivity and hydrochemical data, which allows to derive and establish different salinity maps for different AB/2 spacings, and to outline the boundaries between fresh, brackish and saline waters. Two different alternative approaches have been also developed for geophysically computing and estimating the hydraulic conductivity and the transmissivity of the aquifers in the study region. The different hydrogeophysical approaches developed in this integrated geophysical research project for water resource management have been successfully applied in Khanasser valley, and can be recommended to be practiced in similar worldwide areas.

Water resources detection at Santiago Island, Cape Verde using electromagnetic methods

Abstract Freshwater availability is a growing problem all over the world. This is especially true in drier regions with marked population growth. That is the case at the Cape Verde archipelago off the coast of West Africa. The problem of water availability has been part of the archipelago’s history since the 15th century, when these uninhabited islands were discovered by Portuguese navigators. The inconstancy and shortage of drinking water has always been related to low rainfall and prolonged drought. Most of the islands do not have high elevations, which does not favour orographic precipitation. Population and agricultural activity have always been limited by the use of existing water; either stored from the rainy season or from wells excavated in the valley’s riverbanks. To overcame this condition many boreholes have been drilled since the 1950s and 1960s at the known aquifiers. This was done under the scope of geologic and hydrogeological data and methods. The present study is an electromagnetic geophysical survey at Santiago Island, the biggest and most populated of the archipelago. Beginning in 2005, there was at least one campaign a year until 2009. The surveyed regions are the most important valleys and agricultural areas, where the water needs are bigger. The problem of groundwater is not just its amount and availability but also its quality. The problem of sea or salty water intrusion into the near sea groundwater aquifers was detected at many boreholes and by the wells’ hydrochemistry data. The aim of this EM survey was to image the groundwater condition; location and quality throughout the studied areas. To fulfill this, transient electroMagnetic (TEM) soundings have been done. In addition some very low frequency (VLF) profiles and magnetoteluric (MT) soundings have been carried on to confirm and cross-check TEM data.

Validating SMAP SSS with in situ measurements

Sea surface salinity (SSS) retrieved from SMAP radiometer measurements is validated with in situ salinity measurements collected from Argo floats, tropical moored buoys and ship-based thermosalinograph (TSG) data. SMAP SSS achieved accuracy of 0.2 PSU on a monthly basis in comparison with Argo gridded data in the tropics and mid-latitudes. In tropical oceans, time series comparison of salinity measured at 1 m by moored buoys indicates that SMAP can track large salinity changes occurred within a month. Synergetic analysis of SMAP, SMOS and Argo data allows us to identify and exclude erroneous jumps or drift in some real-time buoy data from assessment of satellite retrieval. The resulting SMAP-buoy matchup analysis leads to an average standard deviation of 0.22 PSU and correlation coefficient of 0.73 on weekly scale; the average standard deviation reduced to 0.17 PSU and the correlation improved to 0.8 on monthly scale. SMAP L3 daily maps reveals salty water intrusion from the Arabian Sea into the Bay of Bengal during the Indian summer monsoon, consistent with the daily measurements collected from floats deployed during the Bay of Bengal Boundary Layer Experiment (BoBBLE) project field campaign. In the Mediterranean Sea, the spatial pattern of SSS from SMAP is confirmed by the ship-based TSG data.

Numerical Simulation of the Salty Water Intrusion after the Construction of Houshan Reservoir, China

The seawater intrusion of the Gou River, China and the impact of Houshan Reservoir are studied using numerical simulations. The results show that the natural seawater intrusion length is 1.66km for Gou River estuary, and once the Houshan reservoir is constructed the intrusion length increases to 1.98km, which is 0.32km longer than the natural condition. At present, the highest salinity at the estuary is around 18‰, and recovers to fresh water environment in 3.0km. After the construction of the reservoir, the salinity value increase to 20‰ at the estuary. To around 2.0km from the estuary, the salinity recovers to the natural condition.

Assessment of the effect of a planned marina on groundwater quality in Enfida plain (Tunisia)

The Enfida aquifer system is of importance to the economic activity of the eastern center of Tunisia. The planning of a marina is likely to present a significant risk on groundwater. Classical physically based modeling is used to better understand salty water intrusion in the aquifers. The transport model (MT3DMS) is coupled with the groundwater model (Modflow). Model calibration was carried out over the period 1972–2005. Four scenarios were then simulated for a 50-year period, to assess the effects of both planned marina and future abstraction regime. We predict a rise in the groundwater salinity generated by the planned pumping infrastructure. The impact of the planned project will be observed only near the marina. However, limited measurements of transmissivity may affect the model’s results. Thus, the second part of the paper is aimed to assess the models output error due to the uncertainty in transmissivity, using a stochastic approach. Hundred realizations of a log-normal random transmissivity field had been performed. According to the most pessimistic realizations, the uncertainty may reach 49 % in the sector of an important pumping field. Accordingly, the calculated concentration may reach 6.5 g/l in 2055 instead of 3.2 g/l.

Analysing the extent (size and shape) of Lake Basaka expansion (Main Ethiopian Rift Valley) using remote sensing and GIS

AbstractThis study attempted to estimate the extent of the expansion of the area of Lake Basaka over the past 50 years (1960 to 2010), using LANDSAT images, field observations, local information and topographic maps. The analysis revealed that the lake has exhibited a dramatic expansion over the past five decades. An increase in the lake water level by 7.6 m over this period resulted in flooding about 45.8 km2 of surrounding areas and an incremental lake volume of about 280 Mm3. About 70% of the lake expansion was observed in the period between the 1970s and 1990s. This phenomenon coincides with the periods of remarkable land use/cover changes in the region. Furthermore, the beginning of the lake expansion coincided with the introduction of irrigated agriculture in the region, and construction of Koka Dam in the mid‐1960s in the upper Awash River Basin. This study suggests that the observed expansion trend, if it continues unabated, could result in certain socio‐economic and environmental consequences in the region in particular, and to Ethiopia in general. Groundwater inundation or salty water intrusion, for example, might occur in the area in the near future, thereby affecting the sustainability of regional irrigated agriculture. The lake has the potential to inundate the surrounding region (Matahara Sugar Estate; towns of Fantalle and Matahara) and might connect with the Awash River during the next 10–15 years. This would affect downstream irrigation developments in the Awash Basin and the livelihoods of people that depend on the basin’s water resources. The overall findings of this study emphasize the need to adopt mitigation measures before the lake expansion results in irreversible damage to the region or the basin.

A study on salt wedge and River Plume in the Seom-Jin River and estuary

A bay in the republic of Korea has experienced significant reclamation and dredging works. Along with such artificial geomorphologic changes, a dam was built in the upstream river, which reduced the discharge of freshwater into the bay. Human induced changes in the coastal shape and freshwater supply have caused significant changes in the river environments, such as strong stratification, bottom salty water intrusion and oceanization downstream, etc. The present work investigated how such geomorphologic and hydrologic changes control the mixing and circulation in the bay and river using numerical modeling. The theoretical length of salt wedge has a relationship with the location, with 16 psu salinity observed as being ecologically important in that area. Coastline change can modified the estuarine circulation within bay but did not stronger effect on the salt wedge than other factors. The change of the interfacial shear can strengthen/weaken the salt wedge due to the discharge variation. Deepening the river channel can strengthen the stratification at the river mouth and elongates the salt wedge to river upstream. A rise in the sea level also enhances stratification and salt wedge.

Investigation of heavy metals in crystalline aquifer groundwater from different valleys of Bangalore, Karnataka

Fifty-one groundwater samples were collected during South-west monsoon 2009 from Challaghatta, Vrishabhavathi, Kormangala and Hebbal valleys, Bangalore, which is an unconfined/crystalline aquifer to investigate Fe, Mn, Cu, Zn, Pb, Cd, Cr, Ni concentrations and other parameters like temperature, pH, electric conductivity (EC) and total dissolved solid (TDS). The TDS and EC variation confirmed light-salty nature of groundwater found to be contaminated by Salty water intrusion, which is attributed to over-extraction. Comparison between presence, abundance and frequencies of trace elements in groundwater samples is in the order of Fe (84) > Zn (72) > Mn (68) >Pb (45) >Cu (41) >Cr (35) >Ni (33) >Cd (21), indicating that Fe in groundwater is in origin. The TDS, Pb, Fe, Mn and Cd concentrations in groundwater samples are beyond the permissible limit prescribed by World Health Organization (WHO). Key words: Groundwater, heavy metals, lithologic physico-chemicals, sewage.

Climate change and its impacts on the coastal zone of the Nile Delta, Egypt

The main objectives of the current work are (1) to determine historic pattern of shoreline changes (erosion and accretion) along the north coast of the Nile Delta, (2) to present a future view on what to be expected regarding climate change impacts, sea-level rise (SLR) scenarios, expected land losses and alteration of some soil characteristics (3) to recognize negative impacts of SLR on the Nile Delta coast and (4) to assess and suggest protection measures. The current investigation was conducted using the advanced techniques of remote sensing and geographic information system. The investigated area with 394 measured locations is located along the northern coast of the Nile Delta between Alexandria and ElTina plain in Sinai peninsula exactly between 29°20′ and 32°40′ E and 29°54′ and 31°35′ N with the minimum erosion values of 1.11 m2, maximum of 6,044,951.64 m2 and total of 16.02 km2. On the other hand, 177 sites showed minimum accretion values of 0.05 m2, maximum of 2,876,855.86 m2 and total of 13.19 km2. SLR was determined by applying the quadrant equation for 10-year intervals using 1990 as the base year. Mediterranean SLR along the Nile Delta coast could be estimated considering three different scenarios (low 0.20 m, medium 0.50 m, and high 0.90 m). Impacts of SLR are divided into (1) primary and (2) secondary impacts. Over the coming decades, the Nile Delta will face greater threat due to SLR and land subsidence as well. Regarding climate change and its impacts on soil characteristics, rapid increase in salinity values during the former three decades were found. This increase may be due to the intrusion of salty water of the Mediterranean. On the other hand, organic matter content decreased due to higher temperature, especially during the summer season. Some protection measures were assessed and suggested to combat or tackle SLR.

The impact of sea erosion on coastal Pinus pinea stands: A diachronic analysis combining tree-rings and ecological markers

Coastal erosion is a widespread phenomenon on sandy coasts throughout the Mediterranean region; along the Thyrrenian coast of Tuscany (Italy), stone pine ( Pinus pinea L.) stands originally planted for the protection of agricultural crops further inland are often damaged. In the present study, a pairwise comparison of stands at different distance from the sea at eroded and control sites highlighted the effects of coastal erosion alone on pine growth and function. Dendroecological analyses made it possible to determine the temporal dynamics of the phenomenon since 1930 and the interactions with climate, whilst additional structural (LAI, sapwood area) and functional (carbon isotope discrimination) measurements were used to discriminate between stress mechanisms. Salty winds, exacerbated by the removal of dunal vegetation, were found to be the most likely cause of the observed growth decline. The presence and, in more recent times, the reduction of surfactants in sea water played an important synergistic effect. The intrusion of salty water in the water table, on the contrary, played a marginal role at the site. Finally, stressed trees were more sensitive to the inter-annual variability in precipitation; at all sites, growth was stimulated by June, November and December precipitation in the current and two preceding years.

Current status of water desalination in the Aegean Islands

Aegean Islands in Greece, mainly the Dodecanese and Cyclades, face a serious problem of water scarcity. The situation has deteriorated over the last years due to the continuous and fast growing tourist development. Moreover, salty water intrusion into the aquifers is seriously threatening the quality of the existing water reserves. In many arid islands water is transported by sea, at a considerably high cost (reaches about 5–8 €/m 3 in some cases) with a tendency to further increase due to rises in the cost of fuels, inflation, etc. Desalination is foreseen as a solution to this problem as it is a process which can provide fresh and potable water in the required quantities, at a much lower cost. This paper presents the current status in Cyclades and Dodecanese, existing water demand and transported quantities of water, and the desalination units that exist in the Aegean Islands. Furthermore, we estimate costs and the associated efforts that are required for the installation of small desalination plants producing useful amounts of fresh water for local needs.

Hydrochemical and isotopic characterisation of the Bathonian and Bajocian coastal aquifer of the Caen area (northern France)

This paper describes the geochemical evolution of groundwater in the Bathonian and Bajocian aquifer along its flowpath. Since this aquifer represents one of the main sources of fresh water supply in the Caen area and has been subjected to a Holocene marine intrusion, its management requires a sound knowledge of (1) the primary conditions and (2) the potential influence of either natural or anthropogenic pressures. Groundwater vertical sampling validity is discussed with the contribution of high resolution temperature logging. The main processes of geochemical evolution along a groundwater flow line and the sea-water intrusion characteristics are discussed using ionic concentrations (Br −, F − and major elements) and isotopes (water δ 2H and δ 18O, TDIC δ 13C and A 14C, sulphate δ 18O and δ 34S). As the 13C content of TDIC is used as a tracer of water-rock interaction, it shows evidence of specific chemical and isotopic evolutions of groundwater within the aquifer, both related to water-rock interaction and mineral equilibria in groundwater. All the above-mentioned tracers evolve downflow: cation concentrations are modified by exchange with clay minerals allowing a high F − concentration in groundwater, whereas Br − and SO 2− 4 concentrations appear to be redox condition dependant. Superimposed on these geochemical patterns, δ 18O and δ 2H compositions indicate that aquifer recharge has varied significantly through time. The chemical evolution of groundwater is locally affected by a salty water intrusion that is characterised by mixing between Flandrian fresh water and sea-water which has interacted with peat as evidenced by a high Br −/Cl − ratio and SO 2− 4 reduction.

Groundwater resources and quality variations caused by gravel mining in coastal streams

We study the effects of gravel mining on the aquifer–river system in the Baix Fluvià area (NE Spain). Field data show that instream mining has caused a decline of the water-table head of the unconfined aquifer along the Fluvià river. Further, dredging in its lowermost reaches reduces its stage and decreases its slope to zero, which facilitates mixing with sea-water, and thus salty-water intrusion from the river into the aquifer. A dimensionless solution of the Boussinesq’s equation is derived to estimate the water-table shape and the amount of groundwater lost as runoff for any given decline of the river stage. A flow and solute transport finite-element model is also used to calculate groundwater loses for the Fluvià case. We find that results of the general analytical solution are consistent with those of the numerical model, which reproduces the actual layered aquifer and a more appropriate domain geometry. Finally, the observed chloride distribution and time evolution are broadly reproduced using the numerical model. It shows that significant chloride plumes develop after the cone of depression of the nearby wells reaches the river. However, a natural clean-up takes place in the absence of pumping when the natural water gradient turns completely towards the river.

Lognormal kriging for the assessment of reliability in groundwater quality control observation networks

Groundwater quality observation networks are examples of discontinuous sampling on variables presenting spatial continuity and highly skewed frequency distributions. Anywhere in the aquifer, lognormal kriging provides estimates of the variable being sampled and a standard error of the estimate. The average and the maximum standard error within the network can be used to dynamically improve the network sampling efficiency or find a design able to assure a given reliability level. The approach does not require the formulation of any physical model for the aquifer or any actual sampling of hypothetical configurations. A case study is presented using the network monitoring salty water intrusion into the Llobregat delta confined aquifer, Barcelona, Spain. The variable chloride concentration used to trace the intrusion exhibits sudden changes within short distances which make the standard error fairly invariable to changes in sampling pattern and to substantial fluctuations in the number of wells.