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The purpose of this paper is to develop and validate a numerical model to study the effect of changing hydraulic parameters on saltwater intrusion in coastal aquifers.

The numerical model SEAWAT is validated and applied to a hypothetical case (Henry problem) and a real case study (Biscayne aquifer, Florida, USA) for different values of hydraulic parameters including; hydraulic conductivity, porosity, dispersion, diffusion, fluid density and solute concentration. The dimensional analysis technique is used to correlate these parameters with the intrusion length.

The results show that the hydraulic parameters have a clear effect on saltwater intrusion as they increase the intrusion in some cases and decrease it in some other cases. The results indicate that changing hydraulic parameters may be used as a control method to protect coastal aquifers from saltwater intrusion.

The results of the application of the model to the Biscayne aquifer in Florida showed that the intrusion can be reduced to 50 percent when the hydraulic conductivity is reduced to 50 percent. Decreasing hydraulic conductivity by injecting some relatively cheap materials such as bentonite can help to reduce the intrusion of saltwater. So the saltwater intrusion can be reduced with relatively low cost through changing some hydraulic parameters.

A relationship to calculate intrusion length in coastal aquifer is developed and the impact of different hydraulic parameters on saltwater intrusion is highlighted. Control of saltwater intrusion using relatively cheap method is presented.

The study investigates the extent to which defects in coastline buildings are influenced by the climatic conditions within the coastal zones.

The study conducted both desk study and field survey. The primary data for the study were collected through a cross-sectional survey of facilities and maintenance managers of randomly selected coastline buildings. Of the 120 self-administered structured questionnaires, 102 were successfully retrieved representing an 85% response rate. Data collected were analysed using charts, relative prevalence index and Spearman's rho correlation visualization technique.

Saltwater intrusion, ocean overflow, extreme rainfall, debris flow, floods and droughts are the prevalent climatic conditions along the coastline. Steel corrosion, foundation settlement, spalling of concrete and fading of finishes are prevalent defects in coastline buildings. The result shows a positive significant correlation between climatic conditions and defects in coastline buildings.

The study compliments literature on buildings resilience and maintenance management, and also provides a basis for streamlining future research on coastline buildings.

The results provide information on climatic conditions and prevalent defects that should be considered during the design and construction of coastline buildings. The information provided could assist construction stakeholders in improving the resilience of coastline buildings.

The study established that coastline buildings are vulnerable to a rapid rate of defect and deterioration which threatens the sustainability of coastline cities. It suggests measures that could improve the resilience of the elements and components of coastline buildings and consequently enhance the safety of life and property, and improve the physical and economic performance of coastline buildings.

In late 2015, the El Nĩno phenomenon induced Vietnam’s worst drought in 60 years, which lasted until mid-2016 and intensified the most expansive saline intrusion in 90 years. The combination of the two hazards resulted in a large-scale disaster, which has led 18 provinces of Vietnam, most of them from the Mekong Delta, to water shortage, insanitation, human and animal diseases, food emergency need and a considerable disruption in local communities’ livelihoods. These devastating effects raise the question of what makes local households vulnerable to drought and saline intrusion. The chapter argues that vulnerability to the natural disaster is not something resulted from external threats, but rather, is derived from the interplay between social structures residing deeply inside the socio-economic systems and agency’s conditions presenting at the household level. Social structures are rules and procedures that constrain and/or enable human actions in agricultural production, risk taking and adaptation. Agency refers to the capacities of disaster-affected households in the Vietnamese Mekong Delta who cultivated third rice crop and suffered heavily from the 2015–2016 disaster. In addition to households’ lack of planning and coping capacities, the constitution of vulnerability to drought and saline intrusion can be attributed to the interaction between farmers’ choice of extra rice crops and the state’s policies and directions in agricultural and irrigation development since 1990s to date.

Seawater intrusion represents a major problem in many coastal aquifers all over the world. It degrades the water‐quality and hence the groundwater may become unsuitable for domestic and agriculture purposes. Due to the direct hydraulic contact between the freshwater and saline water in coastal aquifers and the density difference between the two water bodies, the seawater migrates inland. The problem is exacerbated when the groundwater abstraction rates exceed the natural recharge from rainfall events. The key to controlling this problem is to maintain the proper balance between water being pumped from the aquifer and the amount of water recharging it. The purpose of this paper is to present a coupled transient finite element model for simulation of fluid flow and solute transport in soils with application to study seawater intrusion in coastal aquifers.

The model includes coupling of fluid flow and solute transport. Transient density‐dependent flow and the dependency of dispersion on velocity are considered. After validation, the model is applied to predict the seawater intrusion in the Wadi Ham aquifer, UAE in vertical sections and the results are compared with those from a commercial code (SEWAT) which was used to simulate seawater intrusion in the aquifer in a horizontal section.

A good agreement is observed between the results of the current model in the vertical cross‐section and those of SEWAT in the horizontal cross‐section for the case of Wadi Ham. The results show that the model can predict the extent of seawater intrusion (and the transition zone) and distribution of salt concentration in the aquifer with a good accuracy.

The developed model includes coupling of fluid flow and solute transport in saturated and unsaturated porous media. Transient density‐dependent flow and the dependency of dispersion on velocity are considered. The model has been applied to a real world case study. A combination of the results in vertical and horizontal sections has been used to build a 3D picture of seawater intrusion in the aquifer.

The Indus, Mekong, and Ganges River deltas, which have created one of the world’s largest delta and submarine fan system, currently contribute a major fraction of freshwater to East and South Asia. All these deltas are those regions in the world that face major challenges in their water sector due to population growth, urbanization, industrialization, sea-level rise, and salinity intrusion into inland and water bodies, all aggravated by climate change. Among them, salinity intrusion is currently one of the key issues that directly and indirectly cause water insecurity in East and South Asia, which ultimately hamper livelihood, agricultural production, and social interference. Hence, this chapter gives a comprehensive description on the nature and extent of the salinity problem, its adverse effects on livelihood and water sector, and then the focus goes to current and future sustainable water resource management within the delta to finally move on to conclusion and suggestions.

The purpose of this paper is to evaluate the water quality of the wetland that received treated municipal wastewater for 40 years and its application for nutrients removal and wetland restoration.

To assess the water quality impact of the study, wetland sampling sites were selected to represent the receiving wetland, wetland background, effluent discharge point, and the adjacent canals. Water samples were taken in different seasons of the year and analyzed for water quality parameters including pH, temperature, dissolved oxygen, salinity, chloride, total organic carbon, ammonia, nitrite, nitrate, TKN and phosphorus. USEPA‐approved standard methods were followed and Quality Assurance/Quality Control procedures were compiled. Analysis of variance and Student Newman‐Keuls Post‐Hoc analysis were performed on the sampling results to evaluate the water quality differences among the sampling sites.

No water quality degradation was detected in the wetland study after receiving treated municipal wastewater for 40 years. Dissolved oxygen, pH and temperature were not different from the background level. Total organic carbon and nutrients levels reduced significantly in the receiving wetland, indicating effective waste assimilation. Salinity in the immediate receiving area was reduced substantially, which offers potential application to buffer saltwater intrusion and wetland restoration.

The practice in this study offers potential implications in wastewater nutrients removal, wetland restoration, minimizing saltwater intrusion in coastal wetland.

This study investigated the water quality impact in wetland after receiving municipal effluent for 40 years. Results provide evidence of effective assimilation in wetlands and offer potential applications in coastal wetland restoration.

This study aims to develop a cause-effect relationship between criteria that contribute to water security using the Intuitionistic Fuzzy-Decision-Making Trial and Evaluation Laboratory (IF-DEMATEL) method. Differently from the typical DEMATEL which utilizes crisp numbers, this modification introduces intuitionistic fuzzy numbers (IFNs) to enhance judgments in a group decision-making environment. In particular, the linguistic variables used in IF-DEMATEL are defined using the concept of three-tuple of IFNs.

Data with the linguistic variable “influence” were collected from a group of experts in water security via personal unstructured interviews. Seven water security criteria are considered in this study. Computational software was employed to execute the computational procedures of the IF-DEMATEL method. It is anticipated that by taking into account the hesitation degree of IFNs will reflect the scenario in real life, which could lead to precise decision-making.

The results show that “Over-Abstraction”, “Saltwater Intrusion” and “Limited Infrastructures” are the cause criteria that contribute to water security. In addition, the relationship map of influence shows that “Water Pollution” and “Rapid Urbanization” are the most vulnerable criteria as these two criteria are most easily affected by other criteria in a unidirectional relation.

It is anticipated that these findings will serve as useful references for water security management and policymakers.

The present study makes a noteworthy contribution to the modification of DEMATEL where three-tuple of intuitionistic fuzzy numbers are considered in the computations. The present study also provides additional evidence with respect to factors that contribute to water security.

A computer model based on the fractional step method is presented for modelling density coupled mass transport in groundwater. Although several models utilising the fractional step method had been developed previously, all were based on the Eulerian solution approach. The model developed by the authors uses the Langrangian approach which has some inherent advantages and disadvantages. The problems associated with the implementation of the fractional step method and techniques by which they were overcome are discussed. The performance of the model is examined and results obtained for standard problems are compared with those from other computer packages.

Drought and salinity intrusion aggravated by climate change threaten agricultural livelihoods in Viet Nan's Mekong Delta. In response, authorities have built water management infrastructure for irrigation and salinity protection. This study assessed the impact of one such project, the Ba Lai dam in Ben Tre province, on the livelihoods of aquaculture farmers.

This study uses the Sustainable Livelihoods Framework to assess the impact of the Ba Lai dam on the livelihood capitals of 18 farming households in four communes, located both upstream and downstream of the dam.

The authors find that, apart from some positive effects, the dam has also brought negative environmental consequences, such as increased water pollution. The authors also find that farmers have responded to the changes by adapting their livelihood practices.

The samples were relatively small, encompassing four communes in Ben Tre province. On the other hand, this case study is instructive to the many ongoing infrastructure projects in the Vietnamese Mekong Delta.

The project have caused an increase in water-related social conflict.

The case of the Ba Lai dam provides a cautionary example for infrastructure-based water management plans, both in Viet Nam and more broadly. The study suggests the need to strengthen community participation and prioritize impacts of farmers' capital assets when constructing water management infrastructure for climate change adaptation.

The proportion of long-distance migrant birds at the border of Germany, Austria, and Switzerland decreased between 1980 and 1992 because winter temperature increased. Deterioration in the Amazon, observed in the Xingu National Park, has become more serious during the past few years. The melting of Glazier in many places, especially in the European Alps and in the United States, is another classic example of changing ecosystem caused by the climate change. One prediction indicates that the glaciers in Mount Kilimanjaro will be gone by 2020. Natural disasters, also associated with climate change, are predicted to increase not only in terms of the frequency but also in the size of damages they can cause. From Bangladesh to Vietnam, from Pacific Islands to Latin America, scientists predict that hectares and hectares of mangroves will be flooded due to the rise of the sea level. People in some countries suffered from undrinkable water because of the saltwater intrusion caused by climate change–related hurricanes. In the other extreme, some places experienced drought that caused serious water shortages and loss of biodiversity and agricultural products (e.g., Australia, in 2002, and India, in 2003). Disappearance of habitats and ecosystems caused by climate change are serious, but a short-term challenge in terms of declining productivity in many farm areas are equally serious, if not more so.