Implementation of the Water Resources Classification
System and Determination of the Resource Quality
Objectives for Significant Water Resources in the Letaba
Catchment
7: Overview of the Multi-Criteria Decision Support
System to evaluate scenarios and identify draft
Management Classes
3 April 2014
Presented by:
Pieter van Rooyen
Letaba NWRCS steps
1: Delineate units of analysis and describe the status quo
2: Initiation of stakeholder process and catchment visioning
3: Quantify EWRs and changes in Ecosystem Services
4: Identification and evaluation of scenarios within IWRM
5: Draft Management Classes
6: Resource Quality Objectives (EcoSpecs & water quality (user))
7: Gazette class configuration
Scenario Analysis: Where does it fit in?
22
What needs to be evaluated?
• Degree of the ecological health
defined by Ecological Categories
of biophysical nodes (nonemonetary)
• Ecosystem Services (nonemonetary)
• Socio-Economic implications
(quantitative: monetary and nonmonetary (job count))
How is it rated?
• Ecological consequences are rated according
to the degree that the Recommended
Ecological Category is met. (REC is the top of
the scale.)
• Ecosystem Services, present state is “1.0” with
relative rating for scenarios.
• Economic Indicator, in general GDP or other
relevant comparative monitory indicator.
• Employment, number of jobs as affected by
scenario.
• Integrated rank, weighted scores of above 4
variables – two methods of ranking.
Why Multi-Criteria Analysis?
• Method to compare alternatives where the
outcomes (consequences) are not all
quantifiable.
• Ecological consequences is a relative rating
while economy is in monetary terms and
employment in numbers.
• Multi-Criteria Analysis is appropriate in
these circumstances.
Integrated Assessment of Scenarios
Elements
Variables
Water
Resource
System
Integrated
Units of
Analysis
River
Reaches
(Resource Unit)
Ecological
health
Ecosystem
Services
SocioEconomic
Implications
Biophysical
Nodes
Scenario Assessment
For each reach / node
For IUA / system
For all
scenarios
Relative importance
Ecology
Fish
Food, fuel
Invertebrates
Weighting
process
Riparian
vegetation
Prevailing situation
Services
Weighting
process
Cultural
Jobs
Score
Relative to present
provisions
Makeup of economy
Economy
GDP
Degree of
meeting REC
Ecosystem
Regulating
Score
Household
Income
Weighting
process
Relative to base
condition
Score
Integrated Comparison (all three variables)
Multi-criteria assessment method
Deriving the Management Class
River Reach
B81A-00242
B81A-00256
B81A-00263
B81A-00270
B81B-00233
B81B-00234
B81B-00246
B81B-00251
B81B-00269
B81B-00227
B81B-00240
B81B-00247
EWR1
Total length
Ecological Categories
for a Selected
Scenario
(IUA 1)
EC
C
D
D
C
C
C
C
D
B
D
C
C/D
C
Length (km)
21.9
5.3
5.1
20.2
3.2
7.1
14.7
3.7
6.5
11.0
10.2
12.5
25.7
147.1
Pd =
𝐷𝑙
Total length
Pc =
𝐶𝑙
Total length
Pb =
𝐵𝑙
Total length
Pa/b =
𝐴/𝐵𝑙
Total length
Management Class Criteria
% EC representation at units represented by
biophysical nodes in an IUA
≥ A/B
0
Class I
Class II
Class III
Either
Or
Dominated
by?
≥B
60
≥C
80
≥D
95
<D
5
A & B EC
0
70
90
10
C EC
0
80
20
D EC
100
Management Class: I, II or III
Questions for clarification