Challenges in Managing and Developing the Region's Water Resources

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Challenges in Managing and Developing the Region's Water Resources Powered By Docstoc
					The Berg River Project - RDM
          Process

                          By
                      Cate Brown
  Southern Waters Ecological Research and Consulting cc




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    Western Cape System Analysis
   1989-1995
   Reconnaissance level study of future needs and
    available water sources
   Prioritisation of schemes for further investigation
   More than 24 schemes evaluated
    – Yield
    – Costs
    – Relevant Environmental Impact Prognoses (REIPS) conducted by
      DWAF
    – Included water demand management

                                                                     3
Western Cape System Analysis Evaluation of Options




                                                 4
             Berg Water Project
       Selection of Skuifraam Dam &
           Supplement Schemes
   Skuifraam Dam
    – Least expensive option with significant storage
    – Acceptable environmental impact with mitigation
    – Close to existing infrastructure (Riviersonderend-Berg
      River tunnel system)
    – Replaces Assegaaibos Dam (originally planned to
      divert Berg River into the Riviersonderend- Berg River
      system)
    – augmented with Supplement Scheme
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    BERG RIVER PROJECT PRINCIPAL
             FEATURES
Berg River Dam               Supplement Scheme

•   Yield                    • Yield
         56 million m3/a       ~ 25 million m3/a
•   Gross storage capacity   • River diversion
         127 million m3
                             • Pump station & 9km
•   Maximum wall height
                60 m           pipeline
•   Length of dam wall       Berg River Project
               990 m
                             • Total yield
•   Gross catchment area
        77 km2                 ~ 81 million m3 /a


Estimated cost of BWP is approx R1.4 billion
                                                    6
 Skuifraam
supplement
 Skuifraam

             7
         RDM-related activities
1991 Initial IFR determination for the Berg River
1993/4 Preliminary determination of flows for the estuary
1995 IFR Refined
1997 Reserve-related assessments for the Skuifraam
  Supplement Scheme (based on 1995 IFR work)
1998 NEW WATER ACT
1999 Reserve-related assessments for other schemes
2000 Skuifraam Outlet Works – discussions
2000 Independent Review of the Flood Releases
2002 IRD for the lower Berg River
2003 DWAF Approval of the upper Berg River Reserve
2003/present Berg River Monitoring Programme
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    Reserve determination process
   Used the Building Block Methodology
     - Motivates for the inclusion of specific parts of the flow regime (water
       quantity)
     - Provides a single IFR to maintain a river condition
   Water quality reserve
   Public participation process
     -   Damage Control IFR
     -   Good agreement between IFRs along the length of the river
     -   Scope for further development
     -   Less water available in summer than in winter
   31% MAR (44 MCM out of 141 MCM per annum)
     - Caps summer releases
     - Requires winter flood releases: 65 m³/s and 160 m³/s


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            Reserve process – cont.
   Design costs of outlet to release floods
     - Independent review
     - Multi-disciplinary workshop
     - Decision
   Restrictions as a result of capping flows
     - Skuifraam Supplement to protect upper section of river
   Operating rules
     - Ecologists and engineers
     - Reduced duration of floods based on flood hydrograph analysis
     - Recomputed floods and flow requirements in line with agreed volumes
   Berg River Monitoring Programme
     - Key questions
         - flood releases
         - estuarine and floodplain requirements
         - groundwater interactions
     - Condition baseline
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               03 October 2003

DWAF Director General approves Berg River Reserve




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      Implementation challenges

   Future Irrigation Releases into Berg River.
   Environmental releases
     - Low Flows Summer and Winter
     - 65 m³/s and 160 m³/s floods
   Contributions from other impoundments
   Monitoring
   Adaptive management
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posted:4/11/2011
language:English
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