Manuel Winograd
Jeremy Eade
THE USE OF GEOGRAPHICAL INFORMATION SYSTEMS
Geographical Information Systems (GIS) are a useful, and perhaps necessary, tool for incorporating environmental indicators into the development process. The integration of economic, social and environmental indicators in a spatial framework allows for more powerful and realistic analyses than those offered by conventional non-spatial methods. In this way the cause-effects relationships alluded to in indicator models and frameworks, such as the Pressure-State-Impact-Response model, may be identified and analysed with greater accuracy and realism.
Examples of indicators in a spatial framework are shown in Figures 1 to 6. Figures 1 and 2 show the population variable at the four stages of the Pressure- State-Impact-Response model. The non-availability of spatial data for socio-economic indicators means that, for example, population growth and fertility rates (Figures 1 and 2) are mapped at the national level in some cases. However, the increasing availability of geo-referenced census data will facilitate subnational mapping of socio-economic indicators. Figures 3 and 4 present examples of different pressure, state, impact and response indicators for selected variables (economic development, food and agriculture, land use, and biodiversity). An example of the spatial analysis capability of GIS for the development of indicators is the travel time surface for access to towns with populations of over 10,000 shown in Figure 3.
The main advantage in using GIS lies in its ability to perform visual and mathematical overlay. Mathematical overlay methods were used to produce the accessibility map in figure 3. The combination of indicators in Figure 5 is a result of visual overlay. Figure 5 shows the combination of pressure (roads, deforestation), state (urban population) and response (protected areas) indicators. From this map it is evident that most deforestation occurs in proximity to roads and urban population. There is less deforestation in protected areas. This type of visual analysis could be quantified and used to examine causes, effects and interactions under different development scenarios.
Besides spatial analysis, GIS provide a means for organizing large data sets, for example, the UNEP-CIAT Indicators Project has over 200 indicators stored in its GIS database. This database will be distributed on CD-ROM with a simple graphical user interface for access and queries.