Coastal Areas are the 2% land area from the total earth surface that is vulnerable to climate change. Numan and Beatley has mentioned that the 10 % population of the world that mostly live in the largest cities such as Jakarta, Bangkok, London, Mumbai Shanghai, and New York are positioned at the coastline may suffer climate change due to the high risk of Sea level rise that affects increasingly on economic, security and safety of the civilians. The impacts of climate change, including more extreme heat, longer drought cycles, heavier precipitation events, and increased nuisance flooding, are already being witnessed by communities worldwide.
Climate change is known as geographical problems that need to be identified and undergo decision making by geographic apparatus and procedures. Hence, the Geographic Information System (GIS) has provided a solution and contributed highly to experts and scientists to counter the problems by acquiring and accessing this information that is related to factors that cause and solutions for coastal vulnerability to climate change by observing spatial properties of the earth in various locations. As the technology of the world evolves greatly over the 100 years this current and future timeline of technology has provided us an easy way to conduct a survey of the earth’s spatial data by using its computer-based system and remote sensing in order to acquire and produce integrated information for Coastal climate change vulnerability assessment.
GIS is considered to be an excellent tool to examine the vulnerability of climate change in the coastal region as it interacts and observes dimensions of spatial components that interact with one another. This method of acquiring data can provide us with assistance to detect areas that are sensitive due to climate change with data layering, integrating, referencing, and map visualization for further analysis and solution making. This information can be used to help to reduce the impact of climate change on coastal areas where it can be used to acknowledge the problems and spread awareness in order to educate the public and provide decision making.
The vulnerability can be simply known as an event that highly may cause a loss of something important. The International Panel on Climate Change mentioned that vulnerability can be defined as a tendency of sensitive areas and may occur to damage due to established social resources properties and the capacity of time of those resources to accommodate and heal from occurrences. Vulnerability is generally accepted as a feature of exposure, sensitivity, and capacity for adaptation. Exposure is the similarity to a danger of a property or region; exposure measures the degree of effects a disaster can have on the property, and the opportunity to modify and deal with the threat consequence is resilient capability. Exposure, sensitivity, and potential for adaptation are all geographically different. conceptualizations and procedures for vulnerability assessment broad framework have been established. After all, the use of GIS for global climate risk assessments continues to be a challenge, along with the reliability of data and data errors, the communication of ambiguity, and the processing of information in an easily comprehensible way so that it can support the judgment process.
The most alarming disaster due to climate change at the coastline is the Sea Level Rise (SLR). Neutman et al predicted that about ⅓ of the population of citizen that occupied in the coastline will be affected by the threat of rising seawater level for the next 100 years due to flood that may seem normal annually but gradual increases from time to time and may sink the continent. Furthermore, this phenomenon can cause saltwater intrusion that may be affected by our freshwater supply as it degrades the salinity of the groundwater and rivers due to the overflow of flooding from annual rising sea levels. It also can lead to erosion of land and exaggerate the impact of the coastal storms. In places with significant groundwater extraction, saltwater intrusion is driven by sea-level rise, causing saltwater intrusion into coastal aquifers. Deterioration or depletion of drinkable water may be the biggest challenge to their sustainability for remote island communities that depend on coastal aquifers as a water supply. For example, island nations such as Tuvalu and the Marshall Islands are already facing saltwater intrusion. The factors that lead to sea rise level are caused by the melting of ice in the arctic sea and poles by Global warming. FitzGerald has written that the rate of sea-level rise has been a serious issue where the global sea level increase 3.1 mm over the last century after been tested by the tight gauge, and it’s expected to increase rapidly to 0.28 mm This implies that we can see roughly, at a minimum, 1 m of SLR at the end of this century.
After the existence of satellite data acquired due to advanced technology the hurricane activity data can be obtained and evaluated over the period and can be concluded that it has been gradually increasing at the Atlantic Basin. This location has a high sea surface temperature due to the recent increase in hurricane activity in the Atlantic Basin. This is because Hurricane is impacted by the rising of sea temperature where warm surface water making the hurricane to become more intense and produce the strongest hurricanes. Moreover, the increasing sea level of water can worsen the aftermath of hurricanes as it can elevate the water producing high waves that can overtop the sea walls and barriers more frequently. The intense storm that conjunction with sea-level rise can devastate the shoreline of the coast due to erosion and produce flooding broadly.
The vulnerability assessments are established in order to identify a coastal area that has a high-risk impact due to climate change such as strong hurricanes and rising seawater levels and many more. This assessment has strong spatial elements that use GIS for understanding and provide evidence regarding the area affected by climate change. The utility of using GIS in this assessment is to map exposure, physical, and social vulnerability and overlay these elements of vulnerability to detect the most vulnerable spot in the coast area. GIS is a versatile tool for integrating multiple data forms and resources, such as biophysical and socioeconomic vulnerability measures. There is a risk-free social vulnerability, but the effects of that vulnerability can only be evident when prone to climate hazards. Mapping vulnerability by overlaying spatial data and socioeconomic data layers contributes to detecting a location that is vulnerable in order to understand and communicate with other experts for decision making.
The GIS application that used is Bathtub models are an easy method for an area that is exposed to flooding due to the rising of the seawater level and strong hurricanes. These models are used base on the elevation of the grid cells of the projected area where it considered as flooded when the elevation is lesser than the projected sea level. This method of acquiring data conjugates with Digital Elevation Models ( DEM) that is commonly used to process continuous representation of the Earth surface elevation in order to identify Sea level rise or strong storms. Similar to bathtub models, DEM require a distinct x and y coordinats arranged in grid or matrix and elevation value which is the most prior component to access the possible effects by sea level rising.
It is important to precisely map the area that is potential for flooding. Although the simple bathtub model can provide information into coastal areas' vulnerability, however hydrological connectivity or geophysical obstacles are not taken into account. There may be a possibility where the location that have less elevation of projected sea level rising may not considered as flooding due to similar reading with due to construction that esist btween the ocean and projected site is use as protective barriers for example levees, and geophysical barriers, such as dunes . The two connectivity is implemented that known as four sided and eight sided rule rule that explain the possibility of the grid cell is connected to cardinal and diagonal regions that correlate to inundated cell. This method help to decrease the place where it in inuntaded by the landscape features of the protective barrier.
Hydrodynamic models implement the law of physics to explain the water flow for more accurate estimates of exposure. This model list factors that affected floodwater flow such as friction, wind, tides, and barriers, as well as temporal effects. The hydrodynamic model enhanced flood detection dramatically. The selection between static and hydrodynamic models relies primarily on the project's objective.Such strategies can also undermine flood-risk management and optimum distribution of resources. However, input parameters such as friction, wind, and barriers must be carefully described when hydrodynamic models are used . These variables will have a significant influence on the outcome of the model. For example, it was observed that results differ substantially regardless on whether local drainage was accounted for by the hydrodynamic model or not.
In conclusion it is aware that It is important to highlight the growing body of literature as a final part of this review, showing that when spatial analysis systems and visualisation tools are incorporated with the decision-making process, they should be an important help in adapting to climate change. it is beneficial to assess vulnerability to coastal climate threats, including flooding and Sea level rise flooding, with the use of GIS. There are still many relevant research avenues, as well as a number referring to the use of GIS in risk assessments to improve policies and to help societies adjust to different expectations. With multiple political, social, environmental, and economic dimensions, adaptation remains a complex topic. Without the application of GIS it is impossible to identify the changes of climate change in broad and systematic way.
