inventory of impact to identify the potential cumulative effects of a group or series of activity in an area. Any single activity might not be likely to caused serious changes in the environmental but when its effects are added to those of other projects, the impacts of the environment might be severe. The potential for cumulative impacts must be identified and in some cases, this may be possible only at the intra agency level. Thus to account for cumulative impacts at a programme which covers many projects or activities.

A preliminary assessment will indicate the possible impact areas on which detailed data has to be collected for presenting the results of the preliminary assessment will attempt to answer the impacts on physical or health Hazard, economic interest of the existing communities, impact on infrastructure, and future growth pattern in the region for next 20years.

5.1       MATRIX METHOD

The major use of matrices is to indicate cause and effect by listing activities along horizontal axis and environmental parameters along the vertical axis. In this way the impacts of both individual components of projects as well as major alternatives can be compared. The simplest matrices use a single mark to show whether an impact is predicted or not. However it is easy to increase the information level by changing the size of the mark to indicate scale. The greatest drawback of matrices are that they can only effectively illustrate primary impact.

A matrix having rows as environmental attributes or impact areas and columns, having proposed project activities is constructed. Each action having an impact on environmental attributes is given a weight or Parameter Importance Unit (PIU) viewed by experts. Weights given are on following conception.

Weight 1 is given for insignificant low impact, which is not injurious to environment in case of its adverse nature.

Weight 3 is given in case of measurable impact, which is not injurious to environment with proper planning and building in case of its adverse nature.

Weight 7 is given in case of high impact on environment, which can be curbed by taking precautionary measures in case pf its adverse nature.

Weight 10 is given in case of very high impact on environment.                                       .

The predicted environmental impact rated on a scale of environmental scores multiplied by the corresponding weight then gives the weighted impact. All weighted impacts added together give the overall weighted impact of proposed