CHALLENGES IN WATER RESOURCES SYSTEMS OPERATION 1 July 2004 B Mwaka Water Resources Planning Systems – User Forum No. 3

Contents  Sub-directorate: Systems Operation and its functions  Need for Operating rules - requirements from the NWA (1998)  Example of water variation at Kwena Dam  Objectives of operating rules  Phases/Challenges of water resources developments  Achievements by Operating Rules  Benchmarks & Early Warning Systems for stakeholder  Modelling Challenges

Integrated Water Resources Planning National Water Resources Planning Options Analysis Water Resource Planning Systems The Sub-directorate: Systems Operation Integrated Water Resources Planning National Water Resources Planning Options Analysis Water Resource Planning Systems Integrated Hydrological Planning Water Quality Planning Systems Analysis Economic & Environmental Studies Systems Operation

Need for operating rules: Requirements from the National Water Act, 1998 Regulations on use of water to consider… promotion of economic and sustainable use of the water … (Sec 26(4), NWA) The public need to be informed of risks posed due to anticipated droughts, floods and water pollution occurrences (Sec 145, NWA) CMAs/WUAs may temporarily control, limit or prohibit use of water … (Schedule 3, Sec 6), and provide the following information Geographical area or water resources affected Reason for restrictions Date of commencement of measures Actual extent of water shortage Likely effect of shortage on water users Strategic importance or priority of water use

Objectives of Operating Rules  Documentation for standards, transferability and test for efficiency of performance  Regulate availability of water for re-distribution as per demands especially during drought conditions  Flood control for dam safety and mitigation of flood damage

Water storage circle on a developed system Wet season Dry season DSL FSL Drought - Desirable - Controllable - Measurable INPUT OUTPUT - Desirable - Controllable - Measurable Floods

TimeDevelopmentNaturalRegulation depleted available Renewable Potentially available

Challenges due to developments

 Derive annual operating rules  Optimise operation to enhance efficient use of the available water resource  Planned/informed curtailment for equitable and sustainable water supply  Demonstration of impacts of WC&DM, EWR, water wastage etc  Indicate if and when resource will reach its limit Regular (Annual) Operating Analyses

Minimum risk Low risk Medium risk High risk Curtailment month 1 Curtailment month2 No curtailment Curtailment level 1 User sec1 = 100%+ User sec2 = 100%+ User sec3 = 100%+ Curtailment level 1 User sec1 = 70% User sec2 = 90% User sec3 = 100% Curtailment level 1 User sec1 = 50% User sec2 = 70% User sec3 = 90% Curtailment level 1 User sec1 =0% User sec2 = 30% User sec3 = 70% Low risk Minimum operating level Medium risk Minimum risk High risk

WATER RESOURCES PLANNING MODEL (WRPM) RESERVOIR OPERATING MODEL (ROM) RATIONING MODEL DECISION SUPPORT SYSTEMS AVAILABLE IN SOUTH AFRICA WATER RESOURCES YIELD MODEL (WRYM) Historical and long term yield Simulation and scenario testing to define operating rules Do not take into account flow routing and hence EWR operationalisation Modeling Challenges  Meet operating requirements for: oAccurate data monitoring/recording oConflict of interests among stakeholders oUncertainty in water demand/availability projections in the long term oCommunication formats/channels  Decision Support Systems

New requirements for tools in support of Stakeholders  Need to be more user-friendly & interactive  Data storage and sharing capabilities  Easy to maintain and update  Allow scenario testing  Transparency  Equitable participation