Environmental impact
The land suitability evaluation has already classified as "not suitable" any land use that continually degrades the land. An analysis of environmental impact goes further. It compares what will happen under each alternative system of management in terms of the quality of life of the whole community and takes account of effects both within and beyond (off-site effects) the planning area.
In-depth knowledge of physical, chemical and biological processes and how these interact with society is needed to foresee the likely environmental impact of a specific land-use system. Often, the impact of a particular activity may be long term or several stages removed from the primary cause of the problem. For example, in Sri Lanka coastal erosion and flooding have been caused by the exploitation of protective underwater coral barriers for lime production. In West Africa, current coastal erosion has been attributed to big dams, built on major rivers over 20 years ago, which have intercepted the supply of sediment to the coastal zone (Plate 5).
Following are examples of the environmental effects to be considered:
• Soil and water resources. Hazard of soil erosion, landslides and sedimentation; security of water supply and water quality within and beyond the planning area.
• Pasture and forest resources. Degradation of rangelands, clearance or degradation of forests.
• Quality of wildlife habitat. Structure and composition of forests, grasslands and wetlands; critical areas needed to maintain wild plant and animal communities, including germplasm conservation; side-effects of terrestrial developments on wetland ecosystems;
• Scenic and recreational value for tourism and leisure industries. Tolerance of the disturbance associated with leisure, and compatibility with other land uses.