Management of Seawater Intrusion in Coastal Aquifers: A Review

This is the final version. Available on open access from MDPI via the DOI in this recordSeawater intrusion (SWI) is one of the most challenging and widespread environmental problems that threaten the quality and sustainability of fresh groundwater resources in coastal aquifers. The excessive pumping of groundwater, associated with the lack of natural recharge, has exacerbated the SWI problem in arid and semi-arid regions. Therefore, appropriate management strategies should be implemented in coastal aquifers to control the impacts of SWI problems, considering acceptable limits of economic and environmental costs. The management of coastal aquifers involves the identification of an acceptable ultimate landward extent of the saline water body and the calculation of the amount of seaward discharge of freshwater that is necessary to keep the saline–freshwater interface in a seacoast position. This paper presents a comprehensive review of available hydraulic and physical management strategies that can be used to reduce and control SWI in coastal aquifers. Advantages and disadvantages of the different approaches are presented and discussed.British Counci

Mitigating seawater intrusion in coastal aquifers: Novel approach with treated wastewater injection and groundwater circulation

This is the final version. Available from Elsevier via the DOI in this record. Data availability: Data will be made available on request.Seawater intrusion (SWI) is a natural phenomenon that negatively impacts the potability of groundwater and is expected to worsen with rising sea levels due to climate change. Artificial recharge of freshwater is a commonly-used remediation method to mitigate SWI and improve freshwater supply security in affected coastal aquifers. However, limited freshwater availability can limit the effectiveness of this approach. This study proposes a novel mitigation measure, called Inj-GCW, which combines the injection of reclaimed water with the use of groundwater circulation wells (GCW) to enhance the effectiveness of artificial recharge in controlling SWI. GCW is a dual-screened well with isolated screens that extract and inject groundwater into the aquifer. The performance of the proposed measure was quantitatively evaluated using an illustrative simplified unconfined coastal aquifer. Based on the findings, the design parameters were estimated for a field-scale case study of the Nile Delta aquifer (NDA), a large Mediterranean coastal aquifer in Egypt. The study adopts a future scenario that considers Sea-level rise due to climate change and projected population growth by 2100. Results demonstrate that introducing of GCWs into the saltwater wedge, along with injection, effectively retreated the saltwater wedge, due to enhanced velocity, seaward fluxes, and dilution of contamination. Inj-GCW measure led to an 8.9% reduction in SWI and a 5.2% decrease in aquifer salinity compared to the expected intrusion in 2100. Furthermore, the Inj-GCW measure resulted in a 2.2% higher repulsion rate and 0.3% reduction in total salt mass compared to injection alone. The Inj-GCW measure presents a promising solution to SWI challenges in the NDA and other coastal aquifers facing similar issues. The formation of a brackish water bubble at the injection well screen of the GCW and the generated vertical groundwater circulation cells acted as a hydraulic barrier and contributed to the proposed method effectiveness.Ministry of Higher Education of the Arab Republic of Egyp

Prevalence of non-communicable diseases in Brazilian children: follow-up at school age of two Brazilian birth cohorts of the 1990's

<p>Abstract</p> <p>Background</p> <p>Few cohort studies have been conducted in low and middle-income countries to investigate non-communicable diseases among school-aged children. This article aims to describe the methodology of two birth cohorts, started in 1994 in Ribeirão Preto (RP), a more developed city, and in 1997/98 in São Luís (SL), a less developed town.</p> <p>Methods</p> <p>Prevalences of some non-communicable diseases during the first follow-up of these cohorts were estimated and compared. Data on singleton live births were obtained at birth (2858 in RP and 2443 in SL). The follow-up at school age was conducted in RP in 2004/05, when the children were 9-11 years old and in SL in 2005/06, when the children were 7-9 years old. Follow-up rates were 68.7% in RP (790 included) and 72.7% in SL (673 participants). The groups of low (<2500 g) and high (≥ 4250 g) birthweight were oversampled and estimates were corrected by weighting.</p> <p>Results</p> <p>In the more developed city there was a higher percentage of non-nutritive sucking habits (69.1% vs 47.9%), lifetime bottle use (89.6% vs 68.3%), higher prevalence of primary headache in the last 15 days (27.9% vs 13.0%), higher positive skin tests for allergens (44.3% vs 25.3%) and higher prevalence of overweight (18.2% vs 3.6%), obesity (9.5% vs 1.8%) and hypertension (10.9% vs 4.6%). In the less developed city there was a larger percentage of children with below average cognitive function (28.9% vs 12.2%), mental health problems (47.4% vs 38.4%), depression (21.6% vs 6.0%) and underweight (5.8% vs 3.6%). There was no difference in the prevalence of bruxism, recurrent abdominal pain, asthma and bronchial hyperresponsiveness between cities.</p> <p>Conclusions</p> <p>Some non-communicable diseases were highly prevalent, especially in the more developed city. Some high rates suggest that the burden of non-communicable diseases will be high in the future, especially mental health problems.</p

Management of saltwater intrusion in coastal aquifers using different wells systems: a case study of the Nile Delta aquifer in Egypt

This is the author accepted manuscript. The final version is available from Springer via the DOI in this recordSaltwater intrusion (SWI) is a type of pollution that adversely affects the quality of groundwater in coastal aquifers. The Nile Delta aquifer (NDA) in Egypt contains a large amount of freshwater. Increasing abstraction from the aquifer and sea level rise have led to an increase in SWI, which has reached up to 100 km inland. Therefore, practical measures are required to prevent further SWI. This study aims to identify an optimal well system to manage the intrusion of saline water in NDA using a number of management systems, including pumping of brackish water, aquifer recharge, and abstraction of the freshwater. SEAWAT code is used to simulate SWI in the aquifer considering different scenarios of pumping and sea level rise. Four scenarios are used to control SWI, including: decreasing pumping from the aquifer, increasing recharge using treated waste water, increasing abstraction of brackish water for desalination, and a combination of these systems. The results showed that increasing recharge could lead to greater retardation of SWI (19.5%) than decreasing pumping (6.2%) and abstraction of brackish water (5.9%). However, a combined well system of pumping, recharge and abstraction is shown to be a more effective tool to control SWI in coastal aquifers, with retardation percentage of 21.3%.Water and Water Structures Engineering, Faculty of Engineering, Zagazig Universit