Presentation Program Outline

Transcription

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2 Presentation Program Outline MASTERPLAN PROCESS EFFECTIVE PLANNING ELEMENTS DECISION MAKING PROCESS ANALYTICAL HIERARCHY PROCESS (AHP) HOW TO APPLY AHP SIMPLE EXAMPLE CASE STUDY APPLICATION WHDS MDP

3 Decision Making Process

4 Issues in Decision Process for Watershed and Flood Management Planning Choosing the best alternative Dilemma when multiple criteria/objectives

5 Multiple Stakeholders and Project Objectives Integrate in Process

6 Practical Master Plans Needs to Addresses Variety of Issues DRAINAGE INFRASTRUCTURE WATERSHED HYDROLOGY STORMWATER QUALITY SEDIMENT TRANS / STABILITY FLOOD HAZARDS ENVIRONMENTAL PUBLIC FUNDING RECREATION / AESTHETICS

7 Comprehensive Engineering Planning Address Multiple Objectives

8 Optimum Alternative Selection for Master Plan Involves Balance

9 Generalized Master Planning Process

10 General Background Decision Analysis Consider possible consequences of a decision, rather than just predicting the most likely consequence Define objectives and options for decision makers Assess key uncertainties Models used to forecast possible consequences Compare possible consequence to objectives

11 Engineer Decision Making Processes

12 Typical Management Decision Tools / Steps in Alternative Screening Process

13 Multiple Criterion Decision Analysis (MCDA)

14 What is MCDA? Applicable Tool for All Alternative Planning Solving decision and planning problems involving multiple criteria Structures complex problems well and leads to more informed / better decisions Choosing best alternative from set of available alternatives Ability to rank / sort / prioritize alternatives Difficulty originates from presence of more than one criterion Multiple methods of solving MCDA problem including Analytical Hierarchy Process (AHP)

15 Analytic Hierarchy Process (AHP) Analytic Hierarchy Process (AHP) is a technique for handling complex decision making exercises. Instead of prescribing a "correct" decision, the process helps the decision makers find the one that best suits their needs given their understanding of the problem.

16 Situations AHP can be Applied for Improved Decision Making Choice The selection of one alternative from a given set of alternatives, usually where there are multiple decision criteria involved. Ranking Putting a set of alternatives in order from most to least desirable Prioritization Determining the relative merit of members of a set of alternatives, as opposed to selecting a single one or merely ranking them Resource allocation Apportioning resources among a set of alternatives Benchmarking Comparing the processes in one's own organization with those of other best of breed organizations Quality management Dealing with the multidimensional aspects of quality and quality improvement Conflict resolution Settling disputes between parties with apparently incompatible goals or positions

17 Principles of Analytical Hierarchy Process (AHP) Mathematical method based on comparing pairs of alternative (1) solutions and (2) criteria Decomposes problem into hierarchy of sub problems Converts comparisons to numerical values (weights or priorities) used to calculate a score for each alternative Consistency Ratio measures how consistent the judgments have been relative to large sample of purely random judgments CR much in excess of 0.1 indicates judgments untrustworthy

18 Principles of Analytical Hierarchy Process (AHP) Mathematically based solution of an Eigen value problem Results of pair wise comparisons arranged in matrix First normalized Eigen vector of the matrix give the ratio scale (weighting) Largest Eigen value determines the consistency ratio

19 General Steps to Apply AHP 1. Determine criteria or project objectives 2. Define the set of alternatives 3. Evaluate characteristics of the different alternatives (attributes and predicted effects) 4. Define numerical scale for comparison analysis 5. Perform numerical pairwise comparison for all factors 6. Calculation of relative weights of the factor (eigenvector)

20 AHP (Saaty) Rating Scale

21 Details on How to Use AHP 1. Create a table and list the criteria in rows on the left side and in columns across the top 2. In cells where identical criteria intercept (diagonal) enter a value of 1 3. Working row by row determine whether the row is more important than the column using the rating scale

22 Details on How to Use AHP 4. Enter the number (weight) if the row is more important than the column. For example enter 3 if the row is moderately more important 5. If the column is more important than the row, use the inverse. For example, enter 1/3 if column is moderately more important 6. Continue until all cells in table filled 7. Calculate the eigenvectors to determine the relative weightings of each of the criteria

23 AHP Example: Cell Phone Selection Different Phones Selection Preferences Benefits of AHP Converts subjective assessments of relative importance into a set of overall scores or weights Offers a team activity where members must decide on the relative importance of one factor against another Easily removes emotions and helps in making better decisions

24 AHP Example: Cell Phone Selection 3 different cell phones 4 criteria: quality, battery life, design, and other features

25 AHP Example: Cell Phone Selection Evaluate which criteria is most important in pairwise comparison

26 Example: Construct Pairwise Criteria Comparison Matrix Quality (Q) Battery Life (BL) Design (D) Other Features (OF) Quality (Q) 1 Battery Life (BL) 1 Design (D) 1 Other Features (OF) 1

27 Initial Pairwise Criteria Comparison Matrix Principal diagonal contains values of 1 since each factor is as important as itself Apply the scale to determine the pairwise rating Comparison example rating Battery Life vs. Quality where battery life is rated slightly more important or a value of 3 in cell BL,Q and then 1/3 in cell Q,BL Comparison Design vs. Quality where Design is rated much more important than quality (rating = 5) Q,D and the inverse 1/5 for D,Q

28 Example: Overall Criteria Matrix Quality (Q) Battery Life (BL) Design (D) Other Features (OF) Quality (Q) 1 1/3 5 1 Battery Life (BL) Design (D) 1/5 1/5 1 1/5 Other Features (OF)

29 Matrix Solution of Eigenvector Relative Value Vector for Criteria Weighting Approximation for Solving Eigenvectors 1.Multiple entries in each of the matrix 2.Take the n th root of that product Gives very good approximation to the correct answer 3.N th root are summed 4.Sum is used to normalize eigenvector elements to add up to 1.00.

30 Matrix Solution of Eigenvector Cell Phone Example Criteria Weighting Relative Value Vector (RVV) Quality (Q) Battery Life (BL) Design (D) Other Features (OF) TOTALS Quality (Q) Battery Life (BL) Design (D) Other Features (OF) N th Root of Product Value Eigen Vector 1 1/ /5 1/5 1 1/

31 Next Step Pairwise Comparison of Alternative Cell Phones Quality X Y Z Eigen Vector X Y 1/ Z 1/9 1/ Require 4 pairwise comparison in terms of X,Y,Z phones performance for each of the four criteria Battery Life Design Other Features Eigen Vector X Y Z Eigen Vector X Y Z Eigen Vector X Y Z 0.319

32 Final Stage Matrix of Eigenvectors Cell Phone Example (OPM) Multiply Relative Value Vector by Option Performance Matrix to get the optimum alternative ranking Q (W=0.232) BL (W=0.402) D (W=0.061) OF (W=0.305) Eigen Vector X Y Z

33 Cell Phone Example Summary of AHP Results

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35 Understanding of Existing Watershed Constraints

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37 Regional Flood Hazards

38 Summary of Project Phases West Desert Hot Springs MDP - Work Program Phase Description 1 Baseline Data Inventory / Stakeholder Steering Committee 2 Drainage Deficiency and Constraints Identification 3 Planning Level Alternative Drainage System Evaluation 4 Recommended Plan Engineering Analysis 5 Project Reports and Exhibits 6 Environmental Services and EIR

39 WDHS MDP Plan Objectives Steering Committee input to define objectives: 1. Flood protection 2. Water Quality 3. Water Conservation 4. Sediment transport 5. Environmental 6. Costs 7. Recreation 8. Economic Benefits

40 Alternative Formulation / Initial Feasibility Screening Screened Alternatives from 30 to 5 Alternatives: 1.Floodplain Management 2.Combined Flood Control Channels 3.Separate Flood Control Channel 4.Environmental Setback Levee 5.Water Quality / Water Conservation

41 Application of AHP for Alternative Decision Tool Target Objective Comparison Objectives Simplified Normalized Flood Protection Water Quality Water Conservation Sediment Transport Enviornmental Costs Recreation Economic Benefits Eigen Vector Weighting Flood Protection % Water Quality % Water Conservation % Sediment Transport % Enviornmental % Costs % Recreation % Economic Benefits % Normalized Weighting 13.5% Flood Protection 13.5% Water Quality 14.7% Water Conservation 14.1% Sediment Transport 11.4% Enviornmental 14.4% Costs 6.9% Recreation 11.5% Economic Benefits

42 Results of Alternative Selection Process REGIONAL ALTERNATIVE Flood Protection Water Quality EVALUATION CRIETERIA PROJECT OBJECTIVES Water Conservation Sediment Transport Environmen tal Costs Recreation Economic Benefits TOTAL SCORE Weighting Factor Floodplain Management Water Quality /Water Conservation Environmental Setback Flood Control Separate Flood Control Combined Hybrid 0

43 Strength/Weakness AHP for Flood/Watershed Planning 1. The analytic hierarchy process (AHP) is a method that breaks down decision making into series of pair wise comparisons. 2. Main advantage ability to rank choices in order of their effectives in meeting conflicting objectives. 3. Calculations are not complex 4. Other strength is ability to detect inconsistent judgments 5. Limitation is it only works because matrices are all in the same mathematical (positive reciprocal matrix) 6. Changing the scale can modify results (i.e. from 1 to 9 using 1 to 29)

44 Or Resort to the Standard Process

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