Using the Analytic Hierarchy Process to identify parameter weights for developing a water quality index

- AHP was used to identify parameter weights in the West Java Water Quality Index.
- Two AHPs were employed using 13 parameters from within 7 water quality groupings.
- A pool of respondents were independently surveyed to obtain their judgement.
- Results of both AHPs estimated relatively high weights for COD, DO and FC.
- Results will be used for parameter aggregation in development of West Java WQI.

One of the most common approaches used to evaluate the state of water quality in a water body is through the use of water quality indices (WQIs). This paper presents one of the most important steps in the development of a WQI, which is that of establishing the weights of the water quality parameters. The Analytic Hierarchy Process (AHP) was employed to calculate weights based on 13 selected parameters from within 7 water quality groupings for rivers in West Java, Indonesia. Thus, two AHP models were employed in this study, the first had 13 pairwise questionnaires to be compared (individual form) and the second model had 7 comparisons (group form). A pool of respondents from related stakeholders with different backgrounds in West Java was surveyed to obtain their judgement independently. In the first AHP model, both chemical oxygen demand (weights in the range 0.102-0.185) and dissolved oxygen (weights in the range 0.103-0.164) consistently received relatively high weights, compared to other water quality parameters. Meanwhile, in the second model, oxygen depletion (weights in the range 0.160-0.233) and microbiology (weights in the range 0.098-0.249) had high weights. Thus, both models estimated relatively high weights for COD, DO and FC. However, considering that the second AHP model can provide individual weights as well as weights of parameter groupings, this model was preferred in this study. Therefore the results of the second AHP model will be used for the remaining steps in the development of the West Java WQI in the future.