Investigating seawater intrusion due to groundwater pumping with schematic model simulations: The example of the Dar es Salaam coastal aquifer in Tanzania

Camp, Marc Van; Mtoni, Yohana Enock; Mjemah, Ibrahimu Chikira; Bakundukize, Charles; Walraevens, Kristine

doi:10.1016/j.jafrearsci.2014.02.012

Cited by 61 publications

(35 citation statements)

References 17 publications

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“…The primary effect of aquifer overexploitation, i.e., the piezometric lowering, which is mainly due to increasing water demand, droughts, and/or climate change, is amplified in coastal aquifers in terms of quality degradation due to seawater intrusion and consequent salinization, bringing together quality and quantity degradation. As a result of seawater intrusion, wells could be abandoned and/or large volumes of fresh groundwater could be salinized to the point that it becomes dangerous for a number of uses, causing reduction of both groundwater quality and availability [2]. Groundwater discharge increased over the second half of the 20th century; as a consequence, a great number of aquifers are currently overexploited.…”

Section: Introductionmentioning

confidence: 99%

Monitoring and Management of Karstic Coastal Groundwater in a Changing Environment (Southern Italy): A Review of a Regional Experience

Polemio

2016

Water

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Abstract:The population concentration in coastal areas and the increase of groundwater discharge in combination with the peculiarities of karstic coastal aquifers constitute a huge worldwide problem, which is particularly relevant for coastal aquifers of the Mediterranean basin. This paper offers a review of scientific activities realized to pursue the optimal utilization of Apulian coastal groundwater. Apulia, with a coastline extending for over 800 km, is the Italian region with the largest coastal karst aquifers. Apulian aquifers have suffered both in terms of water quality and quantity. Some regional regulations were implemented from the 1970s with the purpose of controlling the number of wells, well locations, and well discharge. The practical effects of these management criteria, the temporal and spatial trend of recharge, groundwater quality, and seawater intrusion effects are discussed based on long-term monitoring. The efficacy of existing management tools and the development of predictive scenarios to identify the best way to reconcile irrigation and demands for high-quality drinking water have been pursued in a selected area. The Salento peninsula was selected as the Apulian aquifer portion exposed to the highest risk of quality degradation due to seawater intrusion. The capability of large-scale numerical models in groundwater management was tested, particularly for achieving forecast scenarios to evaluate the impacts of climate change on groundwater resources. The results show qualitative and quantitative groundwater trends from 1930 to 2060 and emphasize the substantial decrease of the piezometric level and a serious worsening of groundwater salinization due to seawater intrusion.

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Section: Introductionmentioning

confidence: 99%

Monitoring and Management of Karstic Coastal Groundwater in a Changing Environment (Southern Italy): A Review of a Regional Experience

Polemio

2016

Water

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“…Extensive groundwater extraction in Tripoli region, mainly for agricultural development, has caused substantial seawater encroachment and upconing of the deep saline water into Tripoli shallow aquifer, with Cl − , SO 4 2− and NO 3 − as the major pollutants. In this study, this potential problem is investigated.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, the scattered sebkha deposits in the north, containing large amounts of gypsum, produce high SO 4 2− waters.…”

Section: Discussionmentioning

confidence: 99%

“…The fact that coastal zones contain some of the most densely populated areas in the world makes the need for freshwater even more acute [1]. The intensive extraction of groundwater from coastal aquifers reduces freshwater outflow to the sea and creates local water table depression, causing seawater to migrate inland and rising toward the wells [2][3][4], resulting in deterioration in groundwater quality. This phenomenon, called seawater intrusion, has become one of the major constraints imposed on groundwater utilization in coastal areas.…”

Section: Overview Saltwater Intrusion Into Coastal Aquifersmentioning

confidence: 99%

“…Figure 6c shows the spatial distribution of SO 4 2− concentration in the study area. The main source for increasing SO 4 2− is mixing with seawater, which can add significant amounts of sulfate to freshwaters.…”

Section: Major Hydrochemical Parametersmentioning

confidence: 99%

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Groundwater Overexploitation and Seawater Intrusion in Coastal Areas of Arid and Semi-Arid Regions

Alfarrah

Walraevens

2018

Water

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256

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Abstract:The exploitation of groundwater resources is of high importance and has become very crucial in the last decades, especially in coastal areas of arid and semi-arid regions. The coastal aquifers in these regions are particularly at risk due to intrusion of salty marine water. One example is the case of Tripoli city at the Mediterranean coast of Jifarah Plain, North West Libya. Libya has experienced progressive seawater intrusion in the coastal aquifers since the 1930s because of its ever increasing water demand from underground water resources. Tripoli city is a typical area where the contamination of the aquifer in the form of saltwater intrusion is very developed. Sixty-four groundwater samples were collected from the study area and analyzed for certain parameters that indicate salinization and pollution of the aquifer. The results demonstrate high values of the parameters Electrical Conductivity, Na + , K + , Mg 2+ , Cl − and SO 4 2− , which can be attributed to seawater intrusion, where Cl − is the major pollutant of the aquifer. The water types according to the Stuyfzand groundwater classification are mostly CaCl, NaCl and Ca/MgMix. These water types indicate that groundwater chemistry is changed by cation exchange reactions during the mixing process between freshwater and seawater. The intensive extraction of groundwater from the aquifer reduces freshwater outflow to the sea, creates drawdown cones and lowering of the water table to as much as 25 m below mean sea level. Irrigation with nitrogen fertilizers and domestic sewage and movement of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for the high NO 3 − concentration in the region.

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Groundwater evolution and mean water age inferred from hydrochemical and isotopic tracers in a tropical confined aquifer

Villegas

Paredes

Betancur

et al. 2018

Hydrological Processes

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The coastal confined aquifer in the Gulf of Urabá (Colombia) is an important water source for the banana agro-industry as well as for urban and rural communities. However, the main processes controlling recharge and mixing in the aquifer are still poorly understood. Hydrochemical analyses and stable isotope monitoring were conducted to (a) determine groundwater recharge origin, mean groundwater age, and the main processes governing groundwater chemistry and the potential mixing of marine water and the influence of diffusive processes from the two surrounding aquitard layers.Hydrochemical data indicate that the main processes affecting the dissolved chemical composition include cation exchange, dissolution of carbonated and CO 2 , and silicate weathering. δ 18 O and δ 2 H compositions combined with 14 C data highlight the differences in climatic conditions between the recharge zone and the confined section of the aquifer, which is close to the Atlantic Ocean. Groundwater samples with 14 C ages from recent to 28,300 years BP show a depleted isotopic trend ranging from −6.43‰ to −9.14‰ in δ 18 O and from −43.2‰ to −65.7‰ in δ 2 H. The most depleted δ 18 O and δ 2 H compositions suggest a cooler recharge climate than the current conditions (corresponding to the last glacial period of the late Pleistocene). Depleted δ 13 C values in the total dissolved inorganic carbon indicate the existence of organic material oxidation processes within the geologic formation. These results can be used or transferred to enhance groundwater modelling efforts in other confined coastal aquifers of South America where scarcity of long-term monitoring data limits water resources planification under a changing climate. KEYWORDS Colombia, confined coastal aquifer, isotope and geochemical hydrology, mean groundwater ages, recharge areas and groundwater flow

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Investigating seawater intrusion due to groundwater pumping with schematic model simulations: The example of the Dar es Salaam coastal aquifer in Tanzania

Cited by 61 publications

References 17 publications

Monitoring and Management of Karstic Coastal Groundwater in a Changing Environment (Southern Italy): A Review of a Regional Experience

Monitoring and Management of Karstic Coastal Groundwater in a Changing Environment (Southern Italy): A Review of a Regional Experience

Groundwater Overexploitation and Seawater Intrusion in Coastal Areas of Arid and Semi-Arid Regions

Groundwater evolution and mean water age inferred from hydrochemical and isotopic tracers in a tropical confined aquifer

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