1 GIS is becoming an increasingly useful tool in carrying out wetland management. Wetlands are facing problems due to major proportion of the population in the catchment area, urbanization and industrialization; and various human activities, which has accounted for the over exploitation and leads to degradation and depletion of wetlands.
So in order to manage wetland, GIS specialist collect geographical locations of the wetland using GPS and also coordinates of surrounding features such data can include hydrology, vegetation, soil type and species type thus store the collected data in the database within Arch GIS, that can be used to draw maps that show vulnerable wetlands sites. The analyses of such feature can be used to make important management decisions regarding wetland health and conservation, and also in communicating the value of these systems to the publicities to track changes in a wetland over time.
The application of GIS in wetland management is risk analysis and restoration site identification. By tracking changes in wetland vegetation, hydrology and development over time in GIS, managers and scientists can determine whether or not a wetland is at risk for damage, whether by invasive species, retreat, or erosion. Modelling of future damage to a system. Often when determining whether or not a particular site is appropriate for restoration, analysis in GIS can help identify whether or not the restoration will be successful.
GIS can be used to combine numerous features about a wetland from field and remote data to prioritize wetland restoration site candidates focusing on the characteristics of sites by land cover, disturbance regime, wetness, or another feature of interest. The combination of numerous layers of data in GIS to identify regions of interest and restoration candidates is one of the strongest applications of GIS. Without GIS, it would be impossible or highly challenging to view all of these layers of variables simultaneously and make an informed decision about the management of wetland.
GIS can also be used in the mapping of different features within a wetland over different time scales. Mapping can be done time to assess differences with conservation efforts, management strategies, or before and after a restoration. Since the vegetation and hydrology of a wetland are the major physical components that a restoration often seeks to re-establish, GIS is a perfect method because it allows a researcher to address both simultaneously. By comparing the system before and after the restoration effort, the outcome of the effort can be properly evaluated and its methods improved for future restorations.
2 GIS is a powerful tool and has great promise for use in environmental problem solving. GIS has been found to be very effective to assess the groundwater quality. GIS are designed to manage, analyze and display all types of spatial data. It provides a visualization platform in which layered, spatially distributed databases can be manipulated with ease. This capability makes GIS a powerful tool in conducting groundwater modeling. The application of traditional data processing methods for groundwater modeling is very difficult and time consuming, because the data is massive and usually needs to be integrated. GIS is capable of developing information in different thematic layers and integrating them with sufficient accuracy and within a short period of time.
GIS is used in groundwater modelling for either development of models within GIS, and pre or post processing of model data in GIS. For example topography and land use data may be developed in a GIS, then exported out into a groundwater model, such as MODFLOW. The creation of GIS databases containing land use data, soils information, and other geologic data are essential to groundwater modelling. After the model has been run, the results can be exported into GIS for post processing. Post processing allows for data layers to be developed and displayed in map form. This allows model results to be examined easily, in their spatial context. In some cases, modelling may be done directly in a GIS program, by using overplayed data layers to determine relevant groundwater properties, such as recharge rates and contaminant plume migration.
Increasing pressure on water resources worldwide has resulted in groundwater contamination, and thus the deterioration of the groundwater resources and a threat to the public health. Risk mapping of groundwater contamination is an important tool for groundwater protection, land use management, and public health. The most common application of GIS found during the literature review is creating groundwater contamination vulnerability maps. The map can reveal the areas of extreme and high groundwater vulnerability. Modeling groundwater contamination vulnerability can be divided into a handful of steps. The first step is to construct a spatial database of the area of interest containing information that will affect the vulnerability to groundwater contamination. Information layers such as land use, soil characteristic, bedrock geology, topography, recharge, hydraulic conductivity, groundwater levels, well locations and climate were common data layers have been used. The combination of these layers enables the vulnerability of an area to be assessed for specific pollutants. Once the groundwater contamination vulnerability map is created a classification of the model into vulnerability classes can be created. This is done by ranking the input layers according to their impact on groundwater vulnerability. Some cases using low numbers represent high vulnerability and high numbers represent low vulnerability. Finally, the vulnerability score of each of the layers are combined to create a vulnerability index. Vulnerability index can be represented in either a numerical value or a comparison value such as very high, high, low, etc. Another useful technique is to create a number of models of an area. In each of the models one of the variables is weighted more than the other depending on the degree of impact on the system. The different models are then compared to find common trends and patterns. A graphical representation of vulnerable aquifers, combined with graphical representations of potential sources of contamination and public water supplies would allow decision makers to evaluate current land use practices and make recommendations for changes in land use regulations which would better prevent the groundwater from contamination. For example, it may not be considered responsible to build a new chemical plant in the contributing area of a particularly vulnerable aquifer or area of an aquifer. Additionally, such a representation would provide a quick tool for determining possible responsible parties if contamination is found, thereby expediting the remediation process.
4 At Eskom, we apply GIS in almost all major infrastructures in the network. Before a power station is constructed, to study the site and make sure whether it would have underground water or whether there are certain types of rocks, what are the types of soil layers in the area etc. is all analysed using GIS.