Matrices methods

Impact identification Methods

1. Matrices method Z ibiso Mukwae Mutilifa Latungala Kavela Veronica Nampala James Kanyiki Vilho

2. Matrices methods A matrix is a grid-like table that is used to identify the interaction between project activities, which are displayed along one axis, and environmental characteristics, which are displayed along the other axis 1

3. How it works Using the table, environment-activity interactions can be noted in the appropriate cells or intersecting points in the grid. ‘ Entries’ are made in the cells to highlight impact severity related to the nature of the impact, for instance: T icks or symbols can identify impact type (such as direct, indirect, cumulative) pictorially; N umbers or a range of dot sizes can indicate scale; or D escriptive comments can be made. 2

4. Leopold interaction matrix (1971) The Leopold matrix is the best known matrix methodology available for predicting the impact of a project on the environment. It is a comprehensive matrix, which has 88 environmental characteristics along the top axis and 100 project actions in the left hand column. Potential impacts are marked with a diagonal line in the appropriate cell and a numerical value can be assigned to indicate their magnitude and importance 3

5. It is a two dimensional matrix cross-referencing T he activities linked to the project that are supposed to have an impact on men and the environment. T he existing environmental and social conditions that could possibly be affected by the project. 4

6. Three major groups of matrices The environmental and social conditions are divided in three major groups P hysical conditions : soil, water, air B iological conditions : fauna, flora, ecosystems S ocial and cultural conditions : land use, historical and cultural issues, populations, economy 5

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8. Link action to impact Good method for displaying EIA results ADVANTAGES 7

9. DISADVANTAGES Difficult to distinguish direct and indirect impacts Significant potential for double-counting of impacts Qualitative 8