Abstract | Full Paper | PDF | Printer Friendly Format

Page 2 of 8
| Previous | Next |

Methodology
Five thematic layers were selected for determination of groundwater potential zones for the City. They are: Geology, Geomorphology, Soil Thickness, Slope and Landuse. Different classes were identified for each criterion and these were arranged in decreasing order of weight. Using Analytical Hierarchy Principle (Saaty, 1980), a paired comparison matrix was prepared for the five criteria (geomorphology, slope, soil, geology and landuse) for Guwahati city and individual class weights and map scores were worked out. The paired comparison matrix was prepared for each criterion using Saaty’s nine point scale. The rating used for paired comparison is as follows:

Table 1: Rating scale used in saaty’s AHP model

Weight	Definition
1	Equally likely occurrence
3	Moderately likely occurrence
5	Strongly likely occurrence
7	Very strongly likely occurrence
9	Extremely strongly likely occurrence
The values 2,4,6 and 8 can be used to denote intermediary values

We thus get a matrix A of order n, where n is the number of classes in the criterion. The matrix A is reciprocal and should be consistent. For each element aij of the matrix, the following condition is satisfied:

(1)

By solving the matrix, we can find the weight of each class. In order to solve for weights, the following equation was used:

(2)

where I is an identity matrix of order n and X is the n×1 weight matrix and is the eigenvalue. For a matrix of order n, we get n number of eigenvalues. To calculate the weights, we select the largest value of .

Page 2 of 8
| Previous | Next |