Coastal Aquifer

The hydrological and economic feasibility of aquifer storage and recovery (ASR) of excess desalinated water and managed aquifer recharge (MAR) using tertiary treated wastewater (TTWW) to manage stressed coastal aquifers in Oman has been studied numerically using the code, MODFLOW 2005 and the different transport packages MT3DMS, and MODPATH. The current ASR study aims to assess the feasibility of saving and recovering water for the purpose of supply to the city of MUSCAT during high demand periods by banking excess-desalted water during winter and recover it during the rest of the year. The second objective of the study is to explore the feasibility of MAR using TTWW to mitigate salinity in two costal aquifers in North of Oman exploited for different purposes: domestic water supply (Al-Khod aquifer), and for irrigation purposes (Jamma aquifer). ASR in the Al-Khod Aquifer was explored using Simulation Optimization multi-objective modeling using evolutionary algorithm NSGA-II (namely, the Non-dominated Sorting Genetic Algorithm-II), to generate the set of Pareto optimal solutions according to recharging scenarios. The results show that the potential net benefit of storage and recovery might reach as high as $17.80 million/year. The maximum profitable volume that can be recharged into the aquifer, given the limited number of wells and their locations, is estimated at 8.4 Mm3/year, which is lower than the current excess estimated of 10 Mm3/year. For MAR using TTWW, different managerial scenarios were simulated and analysis of the results reveals that the Jamma aquifer will further deteriorate in the next 20 years if it remains poorly managed. The groundwater level will decline further to exceed 3 m on average, and the iso-concentric salinity line of 1,500 mg/L will advance 2.7 km inland that will severely affect farming activities in the area. However, MAR using TTWW when integrated with the management of groundwater abstraction (e.g., smart water meter, higher irrigation efficiency to reduce the abstraction rate) becomes hydrologically feasible to augment the aquifer storage and controlling seawater intrusion, and hence sustains farming activities. The economic analyses of such situation recommend: (1) injecting TTWW in the vicinity of irrigation wells; (2) investing in smart water meters and online control of pumping from the wells to reduce the abstraction rate by 25%; and (3) a combination of both are feasible scenarios with positive net present values. Recharge in upstream areas is found not economically feasible because of high investment cost of the installation of pipes to transport the TTWW over a distance of 12.5 km. Because the financial resources for investments are limited, scenario (2) shows a Net Benefit Investment Ratio of 4.41 (i.e., investment of a $1 yields $4.41). Although option (3) shows the lowest Net Benefit Investment, it is very attractive from a social perspective because it entails an integrated demand and supply management of groundwater. Farmers are requested to reduce pumping, and the government will invest in injecting TTWW to improve groundwater quality in the vicinity of irrigation wells and to form a hydrological barrier to control seawater intrusion in the long run. The primary objective of MAR for the Al-Khod aquifer is to increase the urban water supply and to sustain the aquifer service with the lowest possible damages from seawater intrusion. A number of managerial scenarios were simulated and progressively developed to reduce seawater intrusion and outflow of the groundwater to the sea. An economic analysis was conducted to characterize the trade-off between the benefits of MAR and seawater inflow to the aquifer under increased abstraction for domestic supply. The results show that the abstracted volume for domestic supply can be doubled under MAR practices if irrigation wells are properly managed and public wells are better located. Even though injection of TTWW is more expensive (due to the injection cost), will result in higher benefits. The results indicate that managing the aquifer would produce a net benefit ranging from $8.22 million to $15.21 million compared with $1.57 million with the current practice. MAR using TTWW is feasible to develop water resources in arid regions, and the best scenario depends on the decision maker’s preference when weighing the benefits of MAR and the level of damage to the aquifer. MAR, as a smart water governance technology, mitigates stresses on aquifer systems in arid zones, maximizes the benefit of using groundwater for both agricultural and domestic purposes while minimizing the adverse socio-hydrological and agricultural consequences of mismanagement of commingled groundwater-TTWW resources at all scales (national, catchment, metropolitan area, village, farm).

Groundwater is one of the Earth's most precious resource. Especially coastal aquifers, are fragile and studied for developing solutions on problems pertaining to evaluation of water quality and management. Recent trends on groundwater studies have succeeded in adopting various advanced techniques to manage the resource. As such, the interest on the recent techniques are increasing to understand several groundwater contamination applications in coastal aquifers. This interdisciplinary book attempts to cover the important techniques and management of groundwater contamination from the disciplines of geology, physics, chemistry, mathematics, statistics, biology, and environmental science. Moreover, the economic feasibility of groundwater science and its applications is increasing among the academics, researchers, students, industrialists, and economists. Hence, recent trends and techniques on groundwater contamination is also made available in form of books, articles and magazines. However, advanced techniques especially based on coastal groundwater quality and quantity application are limited and a book integrating all aspects of this techniques in a single platform is not yet available. This book is divided into five different components. The first will describe the introduction to groundwater contamination in coastal aquifers. The second component of the book will deal with various hydrogeochemical processes. The third part of the book covers case studies of groundwater quality assessment using recent techniques. The fourth component of the book will explain about the various pollutants and contaminants in coastal aquifers. The final Fifth component will discuss the management and remediation methods to control the contamination in coastal aquifers. This book will serve as a key reference in the area of groundwater science. The book will encompass various topics in broader perspectives on groundwater contamination in coastal aquifers with a great potential to provide a significant contribution in the field of hydrogeology. Since, it includes an up-to-date comprehensive holistic information related to groundwater of coastal aquifer. Topics of Interest  Threats of coastal aquifers  Development and management techniques  Issues of coastal groundwater contamination  Water-Rock interaction  Isotopic signatures  Major and trace elemental hydrochemistry  Interaction between groundwater and surface water  Submarine groundwater discharge  Hydrogeochemical reaction between seawater and coastal aquifers  Seawater intrusion  Microplastics contamination  Heavy metal and organic pollutants  Remote Sensing and GIS application  Geostatistical techniques  Geophysical techniques  Artificial intelligence methods  Numerical modelling  Coastal aquifers decontamination and management  Artificial recharge techniques  Assumptions, remediation and quality controls Important Dates Title and one-page Abstract Submission

This essay examines the factors that determine water availability for Loreto, including climate, hydrology, potable water supply, and water demand and use. The study also explores options for increasing the water supply needs in the face of expanding population and development and the challenges of climate change. Specifically, the chapter examines the impact of drought and assess the vulnerability of aquifers owing to climate change. Finally, we discuss the potential impacts of integrally planned tourist developments similar those in Los Cabos, given the precarious nature of Loreto’s water supply, and the need for strategies to prevent, mitigate or compensate this impacts.

ISBN: 978-1-938537-17-2

The effects of uncertainty associated with input parameters and conceptual groundwater flow and transport models are studied and evaluated for radionuclide transport modeling at the Milrow underground nuclear test site on Amchitka Island, Alaska. Two-dimensional numerical ...

Shoreline retreat along extended semi-arid areas of North African coasts are indicative of the imbalance of coastal sedimentary processes due to modern abrupt changes in precipitation patterns and urban growth. Monitoring of the diachronic shoreline position and land-use from 1952 to 2018 in the coast of the Hammamet Bay in central-east Tunisia, using both aerial and orbital photogrammetric scenes and the Digital Shoreline Analysis System from 1887 to 2018, suggests shoreline retreat rates ranging from −1.3 to −5.6 m/yr. Such rates are abnormal when compared to the average of −0.07 m/yr suggested by global-scale assessment modeling for sandy beach evolution. These abnormal erosions extend over 65 km of sandy beaches, resulting from a severe deficit of sediment transport caused primarily by rapid coastal urban growth that obstructs sediment flow to the shoreline. We suggest that the high retreat rates observed in the low-population period of 1884-1931 originated mainly from storm surges and tsunamis, or potentially subsidence in the coastal substratum. Moreover, our analysis of the salinity of shallow coastal aquifers and land coverage suggests that shoreline retreat coupled with rapid urban growth accelerated seawater intrusion ~5 km inland, causing soil desiccation, the development of salt lakes, and reduction of vegetation coverage by ~18%. These abrupt environmental changes have a severe, adverse impact on crop production and food security in these densely populated and economically important areas across significant parts of the North African coasts, sharing similar key environmental parameters with our study site. We conclude that anthropogenic drivers are the major source of shoreline retreat rather than natural ones.

The location of the sharp interface between saltwater and freshwater in a coastal aquifer is determined using optimization techniques. The algorithm is based on the combination of a nonlinear programming and an h-adaptive boundary element method. The objective is to create an automated solution procedure. The effectiveness of the model is demonstrated using several examples in confined and unconfined aquifers.

Generally speaking, there are two approaches for modeling saltwater intrusion—the miscible approach and the sharp interface approach. In the miscible approach, saltwater intrusion is a three-dimensional (3D) density-dependent solute-transport problem. This approach, ...

ABSTRACT An important aquifer in the Brazilian northeastern coast with a long strait strip shape was modeled using the Analytic Element Method (AEM). For the recharge effect, a solution of the one-dimensional flow with accretion was applied. Boundary conditions at the coast and inland were specified by means of image method, with special care to linedoublets and head-given elements. The model was constructed with GNU TimSL code and compared with finite element results showing good agreement.

Des études hydrogéologiques et isotopiques, en utilisant plusieurs éléments chimiques et des traceurs isotopique, c'est-à-dire les ions majeurs, mineurs et traces, δ18O et δ2H ont été menée afin de déterminer les sources de réalimentation en eau de l’aquifère de Chott Meriem et l’origine de la salinité. Les résultats des études géochimiques et isotopiques montrent que les eaux souterraines dans la zone d'étude sont le résultat du développement de l'irrigation qui induit le lessivage des sols qui a été identifié comme la principale source de la minéralisation. Cependant, la salinité de l'eau souterraine, influencée par la dissolution des minéraux évaporitiques (gypse et halite), n'est pas la seule cause de sa dégradation. Il n'y a aucune indication de la présence de l'eau enrichie en 18O et 2H et ne montrent pas de mélange avec l'eau de mer.

Groundwater though immensely important and valuable resource for humankind, it is heavily vulnerable in many parts of the world. This present work reviews on the groundwater vulnerability in the north-western coastal aquifers of Sri Lanka, where water supply is based mainly on groundwater. Excessive exploitation of groundwater from coastal aquifers leads to the sea water intrusion that could affect the use of water for agricultural and domestic activities. Construction of vulnerability maps of groundwater contamination are increasingly becoming popular due to increasing industrial, agricultural, urban and domestic activities that pose threats of groundwater contamination in the north-western coastal area. The aim of the present study was to gather, synthesize, and analyze data from available sources to provide a spatial analysis of parameters and conditions under which groundwater might be contaminated, and also to find out the groundwater vulnerable zones in the shallow and deep aquifers of the areas by applying GIS based DRASTIC model.
The study covered Kalpitiya and Puttalama regions in the north-western coastal belts of Sri Lanka. The overlap techniques were used to provide and produce the vulnerability maps for these areas considering weight coefficients of each layer. This was followed by combining the vulnerability and land-use maps to produces the final risk map of the study. The Kalpitiya unconfined aquifers were very shallow (extends 1-3m below ground level) and shallow (up to 20m below ground level), consisting mainly unconsolidated sand while in Puttalama limestone aquifers were shallow (<20 m) and deep (20-160m). The noteworthy feature in Puttalama is that the deep limestone aquifers often show confined conditions. The results of the vulnerability assessment indicated that in Kalpitiya area, the intrinsic vulnerability to contamination ranged from high and very high due to a) shallow groundwater table and, b) permeable sandy soils of the unconfined aquifer. Specific vulnerability due to nitrate was indicated as high to very high due to high nitrate content that has a clear relationship with land use pattern. Vulnerability due to phosphate was also high where phosphate content up to 10.4mg L-1 was recorded. Additionally, seawater intrusion has caused high chloride content in groundwater (up to 471mg L-1). In the Puttalama area, vulnerability to the contamination was moderate to high mainly due to comparatively deep groundwater tables and less permeable soils. The nitrate-N content exceeds the permissible levels (10mg L-1) that was found more towards the Kalpitiya Peninsula. The phosphate contamination of groundwater in deeper aquifers was also identified in the Vanathavillu area (e.g.: Eluwankulama, Rahalmadu, Serakkuliya) exceeding the permissible level (2mg L-1). The main sources of nitrogen loadings in the study areas appeared to be the excessive fertilizer application and contamination due to human waste. It was also found that the quality of groundwater in Puttalama is adversely affected due to high seawater intrusion whereas in Kalpitiya area it was mainly due to improper agricultural practices. It is proposed that` the present model can be used as an effective tool for decision-makers in managing coastal groundwater resources and land-use planning in the areas.