multi criteria decision making

Multi-criteria decision making (MCDM) is an effective technique in hydrology for analysing and selecting the best alternative or solution from a set of possibilities based on a variety of factors. MCDM can be used in a variety of decision-making processes in hydrology, including water resource management, flood risk assessment, and watershed management

Figure 1The general structure of analytical hierarchy process (AHP) for multi-criteria decision making

Here are some steps involved in applying MCDM in hydrology: 

1. Identify the decision problem: explain the decision problem obviously and the desired outcomes. It may be deciding on the optimal placement for a new dam or choosing the best flood prevention techniques.

 2. Define criteria: Determine and specify the criteria for evaluating the alternatives. Water availability, flood risk reduction, environmental impact, cost-effectiveness, social acceptability, and sustainability are examples of these criteria in hydrology.

 3. Weighting criteria: Give each criterion a weight depending on its value or priority. Expert judgment or procedures such as Analytic Hierarchy Process (AHP) or Analytic Network Process (ANP) can be used to accomplish this.

 4. Generate alternatives: Create a list of feasible solutions to the choice problem. For instance, various flood control measures or reservoir placements.

 5. Evaluate alternatives: Using appropriate assessment methods or models, evaluate each alternative against each criterion. This could include data analysis from hydrological models, statistical analysis, or expert comments.

 6. Aggregation of results: To establish an overall score or ranking for each alternative, add individual evaluations of each alternative across all categories. This can be accomplished through the use of approaches such as the weighted sum model (WSM), TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), ELECTRE (Elimination Et Choix Traduisant la Réality), and others.

 7. Sensitivity analysis: Perform sensitivity analysis to investigate how changes in weights or evaluation procedures affect the final rankings of alternatives

. 8. Decision-making: Make a decision or select the best alternative that matches with the set objectives and criteria based on the data and analysis.

MCDM approaches provide a systematic and clear approach to hydrological decision-making,

 allowing stakeholders to consider several considerations and trade-offs while making complex decisions. It contributes to the evaluation of both technical and non-technical aspects, resulting in more informed and rigorous hydrological management decisions. The expert usually works with the decision makers to properly frame the problem. Analytic Hierarchy Process (AHP (has the advantage of allowing for a hierarchical structure of the criteria, which allows users to focus on specific criterion and sub-criteria while distributing weights. This method is critical since a different structure may result in a different ultimate rating. Criteria having a large number of sub-criteria likely to be given more weight than those with fewer sub-criteria.

The Analytic Hierarchy Process (AHP) is a decision-making tool that helps individuals or groups prioritize and make decisions by breaking down complex problems into a hierarchical structure. It was developed by Thomas Saaty in the 1970s and has since been widely used in various fields, including business, engineering, and healthcare

The AHP consists of the following steps:

1. Define the problem

2. Create a hierarchy: Divide the decision-making issue into a hierarchical framework with three levels: the aim, the criteria, and the alternatives. The aim embodies the overarching objective, the criteria the parameters by which alternatives are assessed, and the alternatives the potential courses of action.

3. Pairwise comparison: Give each set of criteria a relative relevance or preference value by contrasting them against each other. On a scale of 1 to 9, with 1 denoting equal importance and 9 denoting extremely important, this is done.

4. Calculate priority weights: By transforming the pairwise comparison matrix to a normal form, determine the priority weights for each criterion. To do this, divide each element in a row by the sum of its corresponding column.

5. Consistency check: Utilize the consistency ratio (CR) to assess the consistency of the pairwise comparison judgments. Adjustments may be required to assure uniformity if the CR exceeds a predetermined level (often 0.1).

6. Calculate overall priorities: To determine the overall priorities for each alternative, multiply the priority weights of each criterion by the corresponding weights of its sub-criteria (if applicable).

7. Sensitivity analysis

8. Make a decision

The AHP offers a methodical method of decision-making that takes both qualitative and quantitative aspects into account. It provides a methodical assessment of alternatives and aids in decision-makers' understanding of the relative importance of various factors