Concepts and Models of Environmental Hazards - Assignment Example

Introduction Geographic Information System (GIS) is essentially a geospatial technology that refers to a set of tools for gathering, storing, retrieving at will, converting and presenting spatial data from a real world for a specific set of uses. GIS can therefore be looked on as a powerful tool that has found application in mitigating the post-effect of environmental hazards while providing potential risk analysis for societies (Lan, et al, 2004). It is a well-known fact that certain areas are more prone to certain natural hazards than others, a fact that has been acknowledged by the application of GIS more than any other tool. GIS permit the combination of various types of spatial data, with non-spatial data, attribute them and use them as useful information in the various phases of disaster management (Goodchild, et al, 1996). GIS has played a fundamental role in the study of majority of the 20th and 21st century environmental concerns and especially global warming. From the quantification of glacier retreat all the way to the measurement of carbon environmental appropriation, GIS has played a major role in the collection of data, analysis of the same, modeling and also reporting or dissemination of knowledge (Goodchild, et al, 1996). Hazard A hazard is generally any source of potential harm, damage, or health effect on something or someone under particular condition. Hazards can range from biological agents like bacteria to safety hazards like slipping and machine malfunctioning (Toyos, et al, 2007). However, the common way of classifying hazards is by category where you get categories like environmental hazards, biological hazards, and physical hazards among others. Environmental hazards range in nature from geophysical hazards such as flooding, tsunami, volcanic eruption, and earthquakes to biophysical hazards like droughts and diseases. There are also technological hazards like chemical incidents various types of pollutions, and nuclear incidents, all of which threatens the long-term sustainability of the environment. Natural events such as hurricanes and earthquakes are obviously hazardous to man, which is the same case with environmental events like volcanic eruptions and tsunamis (Carrara, & Guzzetti, 1999). The disasters that can be caused by natural hazards are mainly resulting from man’s omission or commission. In this regard, I am referring to man’s actions that either increase susceptibility, or lack of appropriate actions to not only anticipate but also mitigate the possible damage of these events. A common denominator with all hazards is the risk. For an event to be categorized as a hazard it must have certain degree of risk. In fact, the best way to look at a risk is the chance or probability of harming a person if such a person is exposed to a certain event (hazard) that predisposes him/her to such a probability (Carrara, & Guzzetti, 1999). This therefore means that for an event to be classified as a hazard it much be exposing a person to risk of whatever nature. Advantages of GIS In a landslide study, data on hydrology, slope steepness, rock composition, and other factors can be combined with data on previous landslide to determine the conditions under which landslide are likely to occur (Saha, et al, 2005). To analyze all possible factors with manual techniques is almost next to impossible, therefore, only two factors can be analyzed in normal circumstance, after which the composite map are combined with the landslide inventory map. However with GIS, it is possible to analyze various factors that are associated with present conditions and historical events, including presence of infrastructure, present land use, among others (Tassetti, et al, 2008). A good example of the application of this technique can be found in OAS/DRDE, which has been using this technique to overlay maps of slope steepness, geology, slope orientation, vegetation, and hydrology, after which it overlays the results with a landslide inventory map in order to identify factors that are linked to both past and present landslides (Zezere, 2002). The ensuing zonation map offers planners a designation of the level of landslide susceptibility for any given geographical area. Using remotely-sensed data, GIS can be used to; delineate past flood, identify flood-prone areas, and forecast future ones (Tassetti, et al, 2008). In fact, by combining information on; slopes, river carrying capacity, and precipitation regimes, GIS can model flood levels, with the resultant information helping planners and decision makers in determining where to construct reservoir and dams for controlling flooding. GIS can also be used to identify hazard-free zones (areas outside certain impact location of an active volcano in this case) and generate reports on the same through combining; a map showing volcano areas; volcano indexes like past effect, explosivity indexes, periodicity, and similar attributes on one side, with information on human settlements, slope, land use, population density, natural barriers and any other socio-economic and natural resource data of that area (Saito, et al, H, 2001; Alberico, 2002). Lastly, data on any other hazards can be combined to develop new sub-set of data, with each complying with diverse pre-established minimum standards for development. Different Uses of GIS GIS enhances the process of evaluating the environmental effect of change (man-made or natural) on an area’s resources. GIS enables a person to measure areas, calculate degrees, visualize changes over time, report and also share findings. Post-events analysis is equally important, but perhaps most important to communities in modeling potential impacts on all planned and unplanned events and activities that an area will have (Magill, Blong, 2005). This therefore shows the importance of GIS in planning and development process and especially in impact assessment which is an important part of the planning and development process when considering any man-made project or development. Remote Sensing With Use of GIS for Hazards GIS and remote sensing can be used to complement conventional methods that are used in Disaster Management and Mitigation. However, they can only be successful if there is adequate and detailed information about their character, expected frequency and magnitude of the hazard event in an area. With the increased frequency and magnitude of these hazards coupled with the enhanced technical capabilities to mitigate them, getting detailed and adequate information about their character, expected frequency and magnitude has not been a tall order (Magill, Blong, 2005). This is what has made it possible to use remote sensing data like aerial photo and satellite imageries in mapping variabilities of terrain property like water, geology, and vegetation, both in space and in time. Satellite Images particularly, gives a synoptic overview while providing very helpful environmental information, which might range from a whole continent to few meters. One thing that cut across almost all natural hazards is that they must have a certain precursors that can be detected by satellite (Magill, Blong, 2005). This therefore allows remote sensing to monitor these events as they occur. In fact from the vantage point of satellite it is possible to plan for and even operationally monitors these natural hazards. Indeed, a full plan for disaster management is needed to effectively minimize the impact of natural hazards, which goes by the name disaster management cycle. Disaster management cycle normally consists of four phases namely; disaster prevention phase, disaster preparedness phase, disaster relief phase, and disaster rehabilitation phase (Gomez-Fernandez, 2000). In three of four phases, GIS is highly needed. In this regard, I am referring to disaster prevention phase where, GIS is needed to help in managing the large amount of data required for hazard and risk assessment; the disaster relief phase, where GIS is needed in combining with Global Positioning System in search and rescue operation in locations that have been destroyed and where it is hard to find bearing; and also in disaster rehabilitation phase, where GIS is useful in organizing the damage data and the post-disaster survey information, and also in the assessment of locations for reconstruction (Gomez-Fernandez, 2000). Remote sensing with use of GIS has particularly been used in managing and mitigating disasters in several areas scattered across the world. For instance, a GIS incorporating remote sensing has been set up in Algeria which has been effective in the prevention and management of a number of natural hazards, which have been ravaging that country over the years. Among these natural hazards that have received the attention of remote sensing and GIS technologies in Algeria is the forest fires that destroy thousands of hectares every years and earthquakes that are a common risk every year, and other less frequent but still devastating hazards just as the frequent ones. Disadvantages of using GIS Modeling of Particular Hazards With GIS each and every hazard calls for a unique method and approach of analysis. In fact, there are hazards that can even be analyzed using more than one modeling technique. However, using these various approaches has its disadvantages especially bearing in mind the fact that each of these approaches has its unique faults that cannot be reconciled with another (Suzen, & Doyuran, 2004). In fact, most of this GIS approaches have assumptions that might not apply to another approaches thereby exposing GIS in general to criticism. For instance, the GIS multivariate statistics is normally used for large geographical areas, however applying it in a small-scale setting exposes it to variation to any other GIS modeling approach, which is serious stain to its accuracy (Suzen, & Doyuran, 2004). Getting Hold of Data for Modeling in GIS In almost all the cases where GIS is called upon, getting the large amount of data that is normally needed in such cases requires a lot of work. For instance, in landslide hazard analysis, a landslide inventory covering approximately 60% of the area of study is needed. Time information for an extended period of previous such occurrences (landslides) has to be availed, not to mention information on other instability factors (land use, geology, and precipitation) that ought to be considered in a landslide analysis study. Another set of information that also ought to be availed include an areas geotechnical characteristics and geomorphology such as slope and aspect, all of which in majority of the cases are never readily available. Land map use, precipitation maps, land susceptibility are other important information that have to be availed if the analysis is to be comprehensive and accurate. Getting hold of all this combination of information is not always easy if previous experiences are anything to go by. In fact, there will always be a set of information that one might be forced to forego either because searching for it is not cost-effective or is not impossible to gain. For instance, in spite the occurrence of the forest fires in Mongolia, and especially in Batsumber, no sufficient, detailed, dependable and up-to-date information on the accurate spatial distribution and extent of forest fires in this region (Hussin, et al, 2008). The detection of fire in this time and age has been found to be heavily relied on traditional methods like ground survey and the like, a method (ground survey) that cannot offer reliable information on the spots of fire scars, intensity and size (Hussin, et al, 2008). This therefore occasions lots and lots of underestimation of the extent of the fire resulting from lack of monitoring and recording of fire incidents in inaccessible areas and the high costs that are likely to be occasioned by ground survey of such areas. Even the cartographic representation of those areas that were burnt was found not to be available. It is important to note that this problem of lack of vital information to be used GIS is not only confined in the Mongolia case, especially bearing in mind that areas that are seemingly developed and have faced environmental hazards severally in the past have been found not have these vital information, without which no comprehensive GIS and therefore sound hazard management can undertaken (Hussin, et al, 2008). This is a classic example of how getting all the required information to be used in GIS can be tasking if not impossible, information that is a must-have, lack of which compromises significantly the accuracy of the GIS. Accuracy of Modeling Hazards Majority of the computerized GIS are beyond the reach of majority of people. The PC-based GIS which is considered affordable and generally easy to operate cannot produce maps that have adequate details for engineering design let alone of Cartographic quality. This is a serious blot on its ability to provide accurate prediction of hazards. Just as I have noted in this paper, getting hold of the large amount of information that is normally required in an analysis of this kind is usually very involving and at time impossible. The lack of such vital information due to whatever reason usually affects immensely the accuracy of the results that might be gotten from the analysis. Requires a Lot of Data There are many types of GIS all of which have demonstrated to be very important tools in hazard management. However, one thing that cut across all this types of GIS is that they all require large amount of data that at time might as well be overwhelming (Renschler, 2005). Looking at the concept of GIS as essentially a large panel comprising of several opened boxes each of which represent a specifies area in the surface of the earth with large amount of data touching on several attributes of that particular areas (rainfall, soil, population), then it is no doubt that GIS requires a lot of data that at time might be so overwhelming for nobody to mobilize (Renschler, 2005). Time Consumption By using very sophisticated computerized systems that have the ability to analyze baseline scientific data like satellite imagery, GIS has the ability to produce (using plotters) large scale maps of exceptional cartographic quality (Felpeto, et al, 2007). However, the production of the same in this system has been found to be very expensive, time consuming, difficult to operate and even at time exceeding the needs of majority of small planning offices (Felpeto, et al, 2007). The analysis of large amount of data that forms the core of GIS has particularly been found to be extremely time consuming, not to mention the fact that plotters and large digitizers that are able to producing maps of cartographic quality are costly and even difficult to maintain (Lan, et al, 2004). References Alberico, I, Lirer, L, Petrosino, P, Scandone, R, 2002, A Methodology For The Evaluation Of Long-Term Volcanic Risk From Pyroclastic Flows In Campi Flegrei, Journal of Volcanology and Geothermal Research, 116, 63–78. 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