Comparison of weight assignment procedures in evaluation of environmental impacts

Environmental impact evaluation is an essential component in environmental impact assessment (EIA) study for any developmental project, wherein importance assignment to various parameters depends on human judgement/experts opinion, which involves a high order of subjectivity. In order to minimise bias and subjectivity in evaluation of impacts, and hence in decision making, three different methods, viz. Battelle environmental evaluation system (BEES), importance scale matrix (ISM), and a combination of both, are considered in the present study. A case study for a development project (setting up a new industry) in an industrial belt situated in a region, which is rich in biological resources with good agricultural productivity and having high potential for further industrial development, is presented. The results of the other two methods are compared with the widely used method of BEES. Both methods are found comparable to the BEES method. However, it is observed that the ISM approach provides a better tool for reducing bias and subjectivity occurring in human judgement.