2.1 Seawater Intrusion
Seawater intrusion can be defined as, the landward migration of seawater into freshwater coastal aquifers and subsurface movement of seawater into coastal fresh water bodies (Ivkovic et al. 2012). It is a global issue, exacerbated by escalating demands for freshwater in coastal zones and predisposed to the influences of rising sea levels and changing climates in the world (Werner et al. 2013). Most of the coastal freshwater aquifers are particularly susceptible for depletion due to its proximity to seawater (Custodio and Bruggeman 1987).
Seawater intrusion is caused through, prolonged changes in groundwater levels of coastal area due to pumping, changes in land use patterns, climate variations or sea level fluctuations (Barlow and Reichard 2010). The primary detrimental consequences of seawater intrusion are
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These influences comprise both natural disparities and anthropogenic activities (Barlow 2003). The principal driver for movement of the transition zone is the change in the hydraulic head difference between fresh water and sea water of coastal areas (Custodio and Bruggeman 1987). The hydrodynamics associated with seawater intrusion can be discussed with following influencing factors.
2.2.1 Groundwater extraction in coastal shoreline
Groundwater extraction reduces coastal freshwater discharge. Therefore alters the position of the freshwater and seawater interface. The reduction in groundwater head due to the extraction can produce an equivalent localized rising (up-coning) of the underlying saltwater wedge as well as a more regional shift in the position of the saltwater wedge landward(Custodio and Bruggeman 1987). Influence of groundwater extraction for seawater intrusion can be described briefly according to Figure 2.1 and Figure
Investigating the Geographical Processes that are Affecting the Physical and Built Coastal Environment There are three geographical processes that are affecting the physical and built coastal environment, they are; erosion, deposition, and transportation. Erosion is the group of natural processes, including weathering, dissolution, abrasion, corrosion, and transportation, by which material is worn away from the earth’s surface, this is mainly caused by wind, running water, and waves breaking on the coast. Deposition is the depositing something or the laying down of matter by a natural process. Transportation is when sand is moved along the coast by long shore drift. At North Cronulla beach erosion is evident.
a) physical and chemical changes related to tides, waves, currents, sea level and ice cap variations, upwelling, and salinity variations;
Garrison, Tom. "Chapter 12: Coasts." Oceanography: An Invitation to Marine Science. 7th ed. Cengage Learning, 2010. 319+. Print.
There are destructive forces at work against the salt marsh. While a slowly rising sea level has had some effect, the greatest destruction of salt marshes that has taken place is urban and suburban development.
Water is the dominating force of life; it has etched, carved and determined the fate of humanity itself since the beginning of time. All living organisms are reliant on water; forced to migrate or adapt at a turn of events as simple as a drought. Despite pipes, wells and most other man made engineering, even humans still spend their days chasing clouds. So for once on this planet there are no arguments, no debates, as to the fact that we need water to survive. We even depend on the undrinkable oceans coating the earth; that act as a shelter for tens of thousands of ecosystems, food chains, and organisms. Some of which have achieved such a precarious balance, that the loss of any creature in a food web may lead to the downfall of the planet itself. “We are already well into a new geological era… where human interference is the dominant factor in nearly every planetary ecosystem, to the detriment of perhaps all of them” (Lynas, 49). So why exactly are humans shifting such an important balance for the sake of excess? We’re tipping the scale; and might not be able to tell when the water starts to burn. Ocean acidification is a process that disrupts some of the most important biological functions and processes that all living organisms are dependent on.
This fact may be relevant for the future due to the variable sea temperatures predicted for the future, and when passing between tropical and temperate region boundaries. There are further issues linked with elevated boat transport, in particular marine infrastructures, such as sea walls and jetties, built to facilitate the sea trade and tourism industry, have been found to be highly susceptible to invasive species establishment (Bulleri and Airoldi 2005; Glasby et al.,
Human activity is one of the leading causes of the disappearance of coastal wetlands. As the human population increases in coastal cities so does the demand for more land. Urbanization is causing enormous amounts of devastation to the existing wetlands. Unrestricted development is causing the erosion of soil, which is dumping foreign sediments into the wetlands polluting the water and disturbing the ecosystem. According to Lee et al. (2006) “Urbanization is a major cause of loss of coastal wetlands. Urbanization also exerts significant influences on the structure and function of coastal wetlands, mainly through modifying the hydrological and sedimentation regimes, and the dynamics of nutrients and chemical pollutants”. Restrictions on the development...
The picture above shows areas which are red in the UK and northern Europe which would be completely underwater if sea levels were to rise by five meters. It is clearly seen in the picture that a lot of coastal areas would be significantly affected. If coastal areas were to be affected, millions of people would have to be re-located causing many social and economical problems. At the rate in which global sea levels are rising 30mm/year and is set to increase and rise more, these areas highlighted in red would be underwater in approximately 160 years time due to human activity with increasing levels of CO2 in the atmosphere.
Observational records indicate that sea level has already risen between 10 and 25 cm globally over the past 100 years. In addition, the Intergovernmental Panel on Climate Change (IPCC) has projected a sea-level rise of 15-95 cm as a consequence of global warming. Sea-level rise will also increase the depth of coastal waters and increase inland and upstream salinity intrusion, both of which affect fresh and brackish water wetlands. Sea-level rise has the potential for increasing the severity of storm surges, particularly in areas where coastal habitats and barrier shorelines are rapidly deteriorating. These direct consequences of global- and regional-scale changes will increase the vulnerability of coastal wetlands which are already heavily impacted by human activities.
"Ocean Events." GRACE â Uncovering the 2010-11 Decline in Global Mean Sea Level and Its Relation to ENSO (October, 2012). N.p., 8 Oct. 2012. Web. 2 Mar. 2014.
RISING SEA LEVEL AND ITS MAJOR CONTRIBUTORS/COASTAL WETLANDS BEING MOST VULNERABLE AND THE POTENTIAL CONSEQUENCES AND IMPACTS (2 PAGES)
The Aral Sea Disaster Abstract The Aral Sea and the entire Aral Sea basin area have achieved worldwide notoriety due to the environmental disaster. The example of the Aral Sea disaster has sent a signal to the entire international community demonstrating how fast and irrevocable the environmental system can be ruined if there is no long-term thinking and planning in place. This paper gives a broad overview of the policies that have resulted in dying of the forth-largest inland body of water. It concentrates on the policies and approaches of the international organizations towards the problem, describes examples of the projects and presents a conclusion on effectiveness of such policies. Introduction The Aral sea used to be the forth largest inland body of water.
Smith, Zachary A., and Grenetta Thomassey. Freshwater Issues: A Reference Handbook. Santa Barbara, CA: ABC-CLIO, 2002. Print
Rogers, Peter. 2008. "Facing the Freshwater CRISIS. (Cover story)." Scientific American 299, no. 2: 46-53. Academic Search Premier, EBSCOhost (accessed November 4, 2010).