Generating alternative alignments in terrain suitability studies for environmental impact assessments of linear developments

Abstract

The construction of linear developments, such as roads, railways, pipelines and power lines, in South Africa requires a number of alternatives to be considered prior to the submission of a proposed development for an Environmental Impact Assessment (EIA). Though legislation requires a screening or scoping of alternative options prior to the EIA, the use of Geographical Information Systems (GIS) is seldom used in generating alternatives through a Terrain Suitability Study (TSS). The inclusion of a wide variety of specialist in a TSS could ensure a well informed choice of alternatives for the EIA and a choice of optimum corridors, could result in cost savings. This may in turn avoid delays during the EIA process if routes were rejected completely by the public and have to be rerouted and new specialist studies done. This study investigates the benefits of generating alternative corridors in a TSS as part of the preplanning phase of an EIA. The inclusion of a number of specialists and environmental aspects are discussed to ensure a democratic and participative process. Methods for generating alternatives using GIS, are also described. The results are shown to demonstrate how the alternatives were voted for by the specialists and recommendations made on improvement and proceeding into the EIA.