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abstract 734

Integrated Watershed Management Using Multicriteria Decision Making Technique

Author(s): Eun-Sung Chung, Sang-Ug Kim, Kyung-Shin Park, Kil Seong Lee

Keyword(s): integrated watershed management (IWM), sustainability, DPSIR, multicriteria decision making (MCDM), alternative evaluation index (AEI)

Article:

Poster:

Session: OS1k IWRM and water allocation

AbstractMany

urbanized watersheds suffer from streamflow depletion and poor stream quality, which often negatively affects

related factors such as in-stream and near-stream ecologic integrity and water supply. But any watershed

management which does not consider all potential risks is not proper since all hydrological components are closely

related. Therefore this study has developed and applied a ten-step integrated watershed management (IWM)

procedure to sustainably rehabilitate distorted hydrologic cycles due to urbanization.

Step 1 of this procedure

is understanding the watershed component and processes. This study proposes not only water quantity/quality

monitoring but also continuous water quantity/quality simulation and estimation of annual pollutant loads from unit

loads of all landuses. Step 2 is quantifying the watershed problem as potential flood damage (PFD), potential

streamflow depletion (PSD), potential water quality deterioration (PWQD) and watershed evaluation index (WEI).

All indicators are selected from the sustainability concept, Pressure-State-Response (PSR) model. All weights are

estimated by Analytic Hierarchy Process (AHP). Four indices are calculated using various multicriteria decision

making (MCDM) techniques which include composite programming, compromise programming, regime method,

EVAMIX approach, and ELECTRE II. In Step 3 residents' preference on management objectives which consists of

flood damage mitigation, prevention of streamflow depletion, and water quality enhancement are quantified. WEI can

be recalculated using these values.

Step 4 requires one to set the specific goals and objectives based on the

results from Step 2 and 3. Objectives can include spatial flood allocation, instreamflow requirement and total

maximum daily load (TMDL). Step 5 and 6 are developing all possible alternatives and to eliminate the infeasible.

Step 7 is analyzing the effectiveness of all remaining feasible alternatives. The criteria of water quantity are presented

as changed lowflow(Q275) and drought flow(Q355) of flow duration curve and number of days to satisfy the

instreamflow requirement. Also the criteria of water quality are proposed as changed average BOD concentration

and total daily loads and number of days to satisfy the TMDL. Step 8 involves the calculation of AEI using various

MCDM techniques. The indicators of AEI are obtained by the sustainability concept, Drivers-Pressure-State-

Impact-Response (DPSIR), an improved PSR model. All previous results are used in this step.

Step 9 is

estimating the benefit and cost of alternatives. Discrete Willingness To Pay (WTP) for the specific improvement of

some current watershed conditions are estimated by the choice experiment method which is an economic valuation

with stated presence techniques. WTPs of specific alternatives are calculated by combining AEI and choice

experiment results. Therefore, the benefit of alternatives can be obtained by multiplying WTP and total household

value of the sub-watershed. Finally in Step 10 the final alternatives comparing the net benefit and BC ratio are

determined.

Final alternatives derived from the proposed IWM procedure should not be carried out

immediately but be discussed by stakeholders and decision makers. However, since plans obtained from the

elaborated analyses reflect even sustainability concept, these alternatives can be apt to be accepted comparatively.

This ten-step procedure will be helpful in making decision support system for sustainable IWM.

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Integrated Watershed Management Using Multicriteria Decision Making Technique