IEA Training Manual - Module 4

5.2 Spatial analysis

Using Geographic Information Systems (GIS) for IEA

Spatial analysis is the process of modelling, examining and interpreting spatial data and any associated databases. Spatial analysis is a powerful and useful tool for interpreting and understanding geographic areas, evaluating suitability and capability of natural areas, or for estimating and predicting impacts of human development. An example of a spatial analysis you might perform is to overlay several layers of data to show the proximity of different features, such as human encroachment into natural wetland or forest areas, and to identify changes in the boundaries of natural areas over time. Spatial analysis is typically done using various types of computer software, one of which is a GIS.

Mastering the use of spatial analysis tools and methods typically involves years of study and practice, and often is a career choice. It is assumed that participants in this training program are more high level users of the results of spatial information who have or have access to staff with specialist knowledge. However, it is also assumed that reviewing some typical uses of spatial information in IEA would be of benefit. This is neither comprehensive nor in-depth, but provides a starting point for more detailed exploration of the required methods and capacities.

Figure 20: GIS Spatial Analysis (National Geographic Society, 2006)

Geographic Information Systems

Geographic Information Systems are database management systems for handling geographic data. Each geographic feature in a GIS has a location on the earth, and a known relation to everything else around it. These GIS systems can manage data on everything from roads, buildings and utilities, to land use, habitat, and natural areas. Data associated with every feature include its geographic position and related properties. For example, information about a river or waterway may include its water storage capacity, flow rate, nutrient status and depth.

Applications of GIS in IEA
  • View and analyze data from global perspective.
  • Overlay data layers for analysis and mapping.
  • Provide framework for studying complex systems.
  • Powerful tool for analysing changes in landscapes and human impacts.
  • Create simulations and models to predict possible future conditions and effects.
  • Have a a powerful visual and universal language

Not only can you use a GIS to store data, but it is also a useful tool for manipulating and analysing data, particularly to examine spatial relationships among landscape features, and in monitoring long-term changes. For example, using GIS you can easily calculate the area of forested lands within 100 m of a particular road, and identify with point locations where critical or protected areas may be. You could also utilize maps for change detection analysis (determining loss of natural habitats from one time period to the next) that can be used to influence government policies and programmes (Boxes 7 to 10).

GIS is not only a storage and analysis tool, but it is a very powerful visual and universal language. GIS systems are clearly of great value to environmental managers. They exist as standalone data management systems, and can perform analysis of complex data. Simulations and models can be presented in a GIS to help predict potential impacts and future changes under current management programmes or environmental conditions.

Box 6: Vegetation degradation in the Mau Forest on the Mau Escarpment, Kenya

Conservation of forest vegetation on the mountains of Kenya is critical to the water supply and daily life of many people in the Kenya highlands. However, without data, it was difficult to prove that this was an important issue in the state of the environment of the country; a strong illustration of its importance was essential.

In February 2001, the Kenyan government announced its intention to accept requests for licenses for logging over a 353.01 km2 area in the Eastern Mau Forest 85 on the Mau Escarpment. The images in this box show forest degradation in the Mau Forest between 1986 and 2000. Conservationists used data acquired from remotely sensed images to argue the case against the Government’s intention, pointing out that half the dense forest in Lake Nakuru’s catchment area had disappeared between 1973 and 2001. Research has indicated that further destruction of the forest in the upper reaches of the basin could mean that the main rivers that feed Lake Nakuru would disappear. Both UNEP and the Regional Center for Mapping of Resources for Development (RCMRD) in Nairobi buttressed this argument with analysis of the importance, recent human activities in and the potential fate of mountain forests in Kenya, using remote sensing. Not many African societies can claim to be as concerned about natural resources as Kenya now is about its mountain forest resources.

Source: RCMRD from UNEP 2006

Box 7: Analysing long-term changes in the plant communities of Netley-Libau Marsh, Manitoba, Canada.

Netley-Libau Marsh is a large freshwater coastal wetland at the southern end of Lake Winnipeg in Manitoba, Canada. Covering an area of 25 000 ha, it is considered one of the largest freshwater wetlands in the world. It is a complex of shallow lakes and channels through which the Red River flows on its way to the lake. Over the last few decades, there has been a gradual loss of aquatic vegetation and amalgamation of water bodies, with a resulting decline in waterbird populations.

Using spatial data sources (primarily aerial photography, road networks and historic habitat maps) researchers were able to document this loss in marsh habitat. Based on this analysis, they indicate several factors may be contributing, and argue that as a result of these significant changes, the marsh is likely no longer functioning as a healthy coastal wetland. The marsh historically provided benefits to Lake Winnipeg in the form of wildlife and fisheries habitat, and by removing and storing nutrients that would otherwise enrich the lake. These benefits have probably been degraded or lost.

As a direct result of this study, there is renewed interest in the marsh ecosystem and its connection to the lake, which has led to a current research programme that is helping to understand the marsh’s potential for improving the quality of water flowing from the river into the lake.

Source: Grosshans 2004

Box 8: Remotely sensed data to analyse Midrand’s state of environment

Midrand is strategically located halfway between the major urban centres of Johannesburg and Pretoria in South Africa. It has an area of 240 km2 and had a population of 240 000 in 2001. The satellite images in this box show the area in 1985 and 2001. Within this period, data acquired using remotely sensed images showed that 65 per cent of Midrand was transformed for human settlement, crops and industry. In 2001, there were 232 hectares of wetlands and river areas. The dominant ecosystem is a transition of grasslands that contains species that exist in both grasslands and bushveld ecosystems.

These remotely-sensed data for Midrand suggest that effective environmental management strategies are required now to avoid deterioration in environmental quality. The rapid growth of Midrand’s economy is expected to continue, with associated impacts on the environment. Current development trends indicate that if effective environment strategies are not adopted soon, people should expect significant deterioration of the environment.

Source: USGS 2003 from UNEP 2006

Box 9: Acquiring data for the protection of important tourism sites, Lake Nakuru, Kenya

Without time series data, a very slow deterioration of the environment is sometimes difficult to detect. This is particularly the case with protected areas where the pressures on the land may overcome the protection. The satellite images in this box show the deteriorating state of the environment for the “protected” area around Lake Nakuru between 1973 and 2001. Lake Nakuru, located southwest of the city of Nakuru in the Rift Valley, Kenya, is one of the most beautiful tourist destinations in Africa. It hosts the world’s greatest concentration of flamingos, and has many of the animals that have made Kenya an important tourist destination.

In spite of its protected status, the Lake Nakuru area has a high degree of vegetation deterioration. The satellite images show the state of the vegetation in 1973 (above) and 2001 (below). The deterioration is having major impacts on the fluctuations of water flow and on water quality. The satellite images provide data to assess the changing state of the environment of the Lake Nakuru region.

Source: USGS 2003


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