Each cell in the matrix is composed of two elements: The matrix is not exactly a model for EIA, but a way to synthesize and visualize the results of such studies, and Leopold matrix is meaningful only when accompanied by an environmental inventory and an explanation of the impacts identified, their value, mitigation measures and monitoring and control program. In short it is a matrix of cause and effect that adds to its role in identifying impacts the ability to show the estimate of its value. For such a matrix is necessary to define and characterize impacts. When we characterize an impact a number of well-defined legal criteria, and are the : Presence (Notable / Low). Generic nature (+/-). Type of action (direct / indirect). Synergy (single / cumulative / synergistic). Seasonality (short / medium / long term).
Duration (temporary / permanent). reversibility (reversible / irreversible) of the system: if the environment alone is capable of returning to the original quality of the system. Recoverability (Recoverable / Unrecoverable): return to original quality through remedial measures. Continuity (Continuous / Discrete). Periodicity (Periodic / Aperiodic).
On this characterization may be making an assessment of impacts, taking into account the legislative criteria contained in the directive and its subsequent transposition into EU member states. The assessment can be performed with the following classification: Compatible: rapid recovery without corrective measures. Moderate recovery takes some time but does not require corrective action, or just some very simple. Severe: the recovery is time consuming and complex remedial actions. Critical Beat tolerable threshold and is not recoverable regardless of the remedial action (this is the kind of impact that, in theory at least, make a project unfeasible and stop). It is difficult to determine the difference between severe and critical, especially because being recovered or not by corrective measures depends on the budget is handled. When evaluating different methodologies are used: a. Direct prosecution. b. Qualitative aspects. Simple criteria on non-quantifiable features that can be better defined using classes. c. Quantitative Systems: o Partial: application of models, types. or Global: Specific models are made for specific activities. Eg Columbus Batelle method. The severity of an impact will be determined by its magnitude characteristics (in terms of its intensity and extension). We must turn this into a value so rough. For a more concrete formulas exist simple to assign values to the descriptors or characteristics of the impacts to reach a standardized value of all impacts. (E) Extension (specific or broad, with values of 1,3,5). (D) Distribution (punctual or continuous, with values of 1 and 0.5). (O) Opportunity (timely or untimely, with values of 1 and 2). (T) Time (rare, frequent and continuous, with values of 0.5, 1 and 2). (R) reversibility (reversible and irreversible, with values of 1 and 2). (S) sign (+ or -). (M) Size (low, medium, high, with values of 1,3,5). With these values we calculate the Total Impact Index (IT), which has the following formula: IT = (M * T + O) + (E * D) * R * S is valued as follows: 30-50 Critical. Severo 15-30. Moderate 5-15. This would be the impact without corrective measures, after implementation of corrective measures (which would be subtracted,-MC). This is a quantitative analysis and then arrive at a semiquantitative value. METHOD Battelle-Columbus. It has