Posted at 10.04.2018
The shoreline is the region where sea and terrestrial procedures meet and interact. Restrictions of their respected actions are not well known, as processes which can be characteristic of each of these conditions are interrelated. This particular characteristic makes the coastal area highly complex and susceptible to human activities, which oftentimes, cause permanent harm to the natural environment.
Coastal Erosion has turned out to be one of the very most important socio-economic and environmental problems facing government bodies in charge of coastal risk management. Regardless of the major causes of this hazard, which could be human or anthropogenic, it includes caused economic deficits, public problems and ecological destruction. The issue of coastal erosion can increase hundreds of kilometres across the shore collection or it could be localized to small areas impacting surrounding neighborhoods or the tourism industry.
Coastal Erosion has been thought as an all natural process by which coastlines adapt to different sea levels, energy levels, sediment source and existing topography. It poses a challenge when it threatens to demolish real human life and property.
In identifying the issues of erosion, real human value judgements come in as erosion has many societal and natural benefits. Coastal Erosion is usually judged as difficult wherever the pace of erosion, considered in conjunction with monetary, recreational, agricultural, demographic, ecological and other relevant factors, implies that action to solution erosion hazard may be justified and required.
The coast can be used for a number of purposes and predicated on this fact, it's important to devise ways of attaining compatibility among these various uses while at exactly the same time attempting to maintain the natural environment. Confronted with the risk of local climate change and possible sea level increases, it is necessary to put in place elaborate coastal management cases that will consider all elements for planning and sustainable development.
Many recent studies done on Coastal Erosion have contacted the problem in a integrated construction. This integrated procedure takes under consideration the need for deep understanding of the physical environment and the relationships between operations of engaged elements and suitable coastal management ideas. These physical factors are also conditioned by legal, environmental and public factors (Barragan, 2003).
The occurrence of incident of coastal erosion is likely to rise and is becoming an issue of great concern to researchers and authorities in control. Broad level modelling of coastal morphology is a major task for experts and authorities likewise. Several studies have been completed in order to handle this issue and its own determinants (Townsend and Burgess, 2004; Burgess et all, 2002). More descriptive analyses of dangers and replies in coastal hazard management are afflicted by little knowledge of the magnitude and location of erosion threat areas for different shoreline changes and management situations.
The coast is unique because of several marine and terrestrial techniques that happen there. As result of this, there exists need for integration of data relating to different facets and factors of the coastal environment in coverage development and planning.
GIS supplies the right system for data collection, analyses, and storage space and information dissemination. It has the capacity to screen spatial and temporal advancement of functions and factors that control them in order to analyse them better and assess their effect on the coastal environment (Hamada, 2004). In addition, it in a position to identify spatial links between different data tiers leading to the introduction of models for geomorphologic advancement and coastal change prediction.
Several studies using GIS applications and methodologies in coastal risk management have been carried out in several elements of the planet. These studies have lead to the introduction of GIS applications or models and some of the include:
BALTICSEAWEB (Latinen and Neuvonen, 2001)
Oceanic Bigeographic Information Systems (OBIS) (Zhang and Grassel, 2002).
Coastal Erosion and Shoreline Development Legislation (Miller et all, 2003).
SCAPEGIS (Walkden and Hall, 2005).
Dune Hazard Assessment Tool (NOAA Coastal Services Centre, 2003)
These applications have been developed for specific coastal areas as each area requires its own peculiar management strategies and therefore its own GIS request for planning and insurance plan development.
Recent studies in this field have advocated an integrated way (ICZM) which encourages ecological development of coastal areas by mixing the utilization of natural resources in ways that limit damage to the surroundings. In using this process GIS is useful as it supports data integration, storage area, analyses and visualisation.
For the application of GIS to coastal threat management to be carried out, there is dependence on data necessary for the different job to be available and accessible. The data requirements for this include slope, lithology, vegetation, drainage, structural conditions, coastal erosion and real human action etc.
In the coastal environment GIS is being ever more used as a tool for collection, integration of required information and storage space in a data source with a view to being able to access data, producing thematic maps and accomplishing spatial and geo statistical analyses (Latinen and Neuvonen, 2001). Through the process, relevant information is sourced and collected, put together into a geo database, converted into relevant systems and introduced in to the GIS platform. This is useful in the integration and examination of parameters used in coastal vulnerability assessments resulting in coastal risk maps (Doukakis, 2005).
This is beneficial because it provides a versatile system. Data can be accessed and used through the database model system. It also allows data automation, visualisation, editing, mapping, spatial analyses, geo statistical analyses etc.
The flexibility and versatility allows GIS to be utilized in many planning jobs in different situations for example in the region of maps, aerial images, statistics, dining tables and graphs that provide details of the environmental conditions and their spatial distributions can be displayed.
Fig 1. A good example of a cartographic information prepared using GIS for coastal Management. Maps, aerial images, dining tables and graphs that show spatial circulation of environmental conditions are displayed for visualisation. (Rodriguez et all, 2009)
GIS has been useful in studies of prediction and estimation of coastal erosion. The datasets required for this include topographic data, bathymetric data, recession rate data, historical maps and time series data as they express the vulnerable express of the coastal environment and coastal erosion. A number of the applications of GIS include:
GIS allows comparability between cartographic or map information that is geo-referenced which is vital for coastal change analyses.
GIS allows collection of data showing temporal developments of shoreline positions for different times. Such data can be produced from sources like satellite imageries, aerial photographs and cartography digitization. GIS allows integration of data from each one of these sources.
GIS allows shoreline positions related to different yr to be overlaid with a view to aiding the identification of areas that have experienced motions or changes.
GIS helps the computation of erosion and accretion rates. It can this by calculating line lengths and perimeter of polygons.
GIS allows detailed analyses of evolutionary fads. It aids this is of the system and prediction of likely occurrence allowing change expectation and hazard preparedness.
GIS is helpful because new data can be integrated and frequent and dynamic follow-up of coastal techniques can be executed. This allows continued development of models that can be useful in learning other aspects of the coastal environment (Sanchez et all, 2005).
GIS has also been found in dune progression studies and it has been highly useful in the area the data requirements are breeze travel data, swell, sediments, breeze speed, topography, garden soil humidity, bathymetry etc are required. These datasets are needed for the conviction of dune field progression and aeolian travel rates. This in turn enables the characterisation of the sedimentology, geomorphology and meteorology of coastal zones.
Some other studies have made use of GIS as an instrument for analyses and interpretation of coastal erosion model outputs. Utilizing GIS to visualise predictions of coastal erosion provides a vital means of understanding coastal changes and their impacts locally and regionally (Brown et all, 2004). The planned target audience here are policymakers and planners considering visualising erosion predictions and carry out analyses with their implications so that proper mitigation steps can be setup by integrating other data models for impact estimation and decision support.
This basically requires the utilization models developed specifically for coastal erosion and one of such has been (SCAPEGIS) which is a process structured model that establishes the reshaping and retreat of shoreline profiles along the coastline (Walkden and Hall, 2005; Dickson et all, 2005). It was developed from smooth cliff and program erosion model. These models supply the source for SCAPEGIS. It has been used in included assessments of coastal erosion and overflow risk for tactical planning of responses to flood and erosion hazards.
The SCAPE model was run for different climatic and management cases and the results were built-into SCAPEGIS with other auxiliary data for specific visualisation and impact analyses. The good thing about this GIS program is that it allows importation of other erosion models developed with similar data output format.
Fig. 2. The Influences Estimation dialog of SCAPEGIS. Source: (Koukalas et all, 2005)
Fig 3. An example of an Erosion Risk Map displaying recession lines under certain climatic scenarios and management. The land following the yellow range towards the sea is assumed lost as the land between the yellow and blue lines is at risk. (Koukalas et al, 2005)
The constant rise in the degradation of coastal environments has led to the necessity to develop techniques of balancing the protection of folks and the current economic climate against the price of coastal hazards. As a result of this, a multidisciplinary method of coastal management has been suggested (Nicholls et all, 2007).
Coastal environments have grown to be more susceptible to the effects of climate change and rising sea levels. There is also high social, economic and biological value. In order put all of this factors under consideration, the Integrated Coastal Zone Management Platform was suggested with a view to integrating all this factors while at exactly the same time preserving the environment. Methodologies for the application of GIS in this platform have been developed by several establishments like UNESCO, EU and several working organizations (Olsen et all, 2003; IPCC, 2007) to say a few.
Within this construction, GIS is useful due to its ability to get, combine and analyse the several data requirements within an integrated framework. It has been used for coastal dune system studies and shoreline advancement studies (Hernandez et all 2007; Ojeda et all, 2005). GIS aids the integration of required data like dune perimeter, shoreline lines position so that spatial analyses of these data layers can be carried out and some of its software in this regard include:
GIS assists integration, company and structuring of required data units.
GIS assists the development f Digital Elevation Models needed for the estimation of dune size, volumetric advancement and dune migration.
GIS allows for determination of dune morphology, dune slope and orientation.
GIS allows for creation of possible dune predictions depending on sea level rise and waves. 3D GIS has proved to be very useful for this task (Sanchez et all, 2005)
The advantage proposed by SCAPEGIS tools is manufactured obvious in the analyses of coastal erosion model results. It's been proposed that these models be linked with other types of environmental studies like land use models for better gratitude of coastal risk management (Hall et all, 2005).
In coastal erosion and threat management, modelling spatial and temporal measurements of dynamics of the coastal environment are actually some of the most challenging tasks in sea and costal GIS. The switch from the regular series and polygon data structure to digital shoreline is consequently of the need to develop technology for shoreline change recognition and spatial modelling.
GIS has been increasingly used in the development of insurance policy and planning in coastal erosion and hazard management. That is due to the fact that in general management policy implementation there is certainly need for a tool able to store, analyse and screen spatial and temporal data. GIS provides an appropriate platform because of this. It provides a suitable instrument for integration of territorial data, makes adjustable analyses easier, allows for future picture simulations and allows probably dangerous area to be determined.
GIS is also use for evolutionary development analyses and system characterisation which are important in the management of the coastal environment.
However, models used are not always accurate as there are problems and uncertainties and therefore these uncertainties should be systematically investigated when the email address details are being analysed for planning and policy development.
There is also the problem data supply and availability. Data required may well not continually be available or accessible. Within the developed world, usage of such data is more reliable and available. In other areas of the world, required data can be unavailable and where they are really, may be inaccurate.