Methodology 2

Criteria Weighting:

As there were a large number of factors present in locating both stations, all with varying levels of importance, it was necessary to use specific procedures to determine relative importance of criteria. Using simple pairwise comparison of factors in the context of a sound decision making process, we are able to determine relative weights of factors, summing to one. Pairwise comparison was completed using the 9 point continuous scale of IDRISI's WEIGHT module. Upon initiation, the module derives factor weights by calculating the principal eigenvector of the input pariwise comparison matrix (pictured below).

STREAM STATION WEIGHTING

The eigenvector of weights is :

aspect : 0.1799
slopes : 0.1683
ripariandist : 0.5093
roadsdist : 0.0388
vegassign : 0.1037

Consistency ratio = 0.07
Consistency is acceptable.

LAKE STATION WEIGHTING

The eigenvector of weights is :

littoraldist : 0.4149
docksdist : 0.1580
slopes : 0.2451
censusassign : 0.0743
builtupdist : 0.0743
soil reclas : 0.0333

Consistency ratio = 0.04
Consistency is acceptable.

Weighted Linear Combination Multi-Criteria Evaluation:

The weighted linear combination multi-criteria evaluation multiplies each standardized factor image by its factor weight and sums these for results. As each set of factor weights must sum to one, the resulting final suitability map will have the same range as that which was used previously for standardization of factors (ie. 0-255 in this case). Multiplication of this result by constraint images results in non-inclusion of constraint areas in final suitability analysis. Once the final suitability map had been generated using MCE for both stations, sites of suitability > 225 were determined and grouped into spatially contiguous areas. The sites with largest contiguous area and suitability > 225 were selected as the final site locations for both stations. The cartographic model below shows how this was carried out for both stations.

DETERMINING AREAS

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