CLIMATE CHANGE AND WATER RESOURCES: CHALLENGES AND QUESTIONS FOR THE D.W.A.F. School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal, Pietermaritzburg Roland Schulze Professor of Hydrology

THE BASIC PREMISE... Climate change is a global phenomenon, but the problems will be very local and we will have to adapt and plan

WHAT DO WE HAVE TO CONSIDER IN THE WATER RESOURCES SECTOR IN REGARD TO CLIMATE CHANGE? (a)The water sector is an integrating, cross- cutting one

Global Regional Local Sectoral agriculturecoastalhealth - INTEGRATED IMPACT ASSESSMENT -

WHAT DO WE HAVE TO CONSIDER IN THE WATER RESOURCES SECTOR IN REGARD TO CLIMATE CHANGE? (b)The hydrological cycle amplifies any changes in rainfall [PMG note: maps not incuded, please

WHAT DO WE HAVE TO CONSIDER IN THE WATER RESOURCES SECTOR IN REGARD TO CLIMATE CHANGE? (c)Climate change scenarios have to be downscaled to the scale at which DWAF operates [PMG note: maps not incuded, please

The Challenge: GCM  RCM  QC  HRU [PMG note: maps not incuded, please

WHAT DO WE HAVE TO CONSIDER IN THE WATER RESOURCES SECTOR IN REGARD TO CLIMATE CHANGE? (d)Climate change impacts have to address key issues of the National Water Act

Hillslope and Riparian Zone Processes in ACRU (after Meier et al., 1997; Schulze, 2000b)

Concepts, Processes and Assumptions in the ACRU Wetlands Module (after Schulze et al., 1987; with modifications by Schulze, 2001d) UPSTREAM INFLOWS DRAINAGE AND ABSTRACTIONS VARIABLE AREA OF WATER SURFACE OPEN WATER EVAPORATION TRIBUTARY INFLOWS TOTAL EVAPORATION WATER-SOIL INTERFACE IMPERVIOUS LAYER SUBSOIL HORIZON SATURATED CHANNEL STORAGE AND ROUTING WETLAND SPILLWAY VARIABLE TOPSOIL HORIZON PERIODICALLY SATURATED

Schematic of Irrigation Water Demand and Scheduling Options Available in ACRU (after Schulze, 1995 and updates)

WHAT HAVE FIRST RESULTS FROM THE W.R.C. PROJECT ON CLIMATE CHANGE AND WATER RESOURCES IN SOUTH AFRICA SHOWN?

DETAIL “EXPLODES” FROM ANNUAL TO MONTHLY TO DAILY VALUES: TEMPERATURE [PMG note: maps not incuded, please

DETAIL “EXPLODES” FROM ANNUAL TO MONTHLY TO DAILY VALUES: RAINFALL [PMG note: maps not incuded, please

Potential Evaporation is Projected to Increase by % Implications: Enhanced dam evaporation losses Increased irrigation demands [PMG note: maps not incuded, please

Soils are Projected to Become Drier More Often Implications: Reduced runoff per mm rainfall Land use changes Reduced crop yields Higher irrigation demands [PMG note: maps not incuded, please

Fewer, but larger rainfall events may result in more groundwater recharge [PMG note: maps not incuded, please

Shifts in the Distribution of Runoff are Projected to Occur Implications: Reservoir operating rules change Ecological reserve (IFRs) change [PMG note: maps not incuded, please

Implications to Irrigation are Likely to be Significant [PMG note: maps not incuded, please

WHAT COULD THIS IMPLY IN AN ACTUAL CATCHMENT SITUATION? A case study from Swaziland

MBULUZI : CONFIGURATION Mnjoli 1 Irrigation – Local Supply Irrigation – Inter Basin Transfers Irrigation – Mnjoli Dam 17 Irrigation – Multiple Sources Streamflow Gauge Inter Basin Transfers Reservoir

MNJOLI DAM: % OF FULL SUPPLY CAPACITY POTENTIAL IMPACTS OF CLIMATE CHANGE, MBULUZI CATCHMENT (Scenario: T = T + 2°C; P = P – 10%) DRY YEAR AVERAGE YEAR

MBULUZI OUTFLOWS TO MOZAMBIQUE POTENTIAL IMPACTS OF CLIMATE CHANGE, MBULUZI CATCHMENT (Scenario: T = T + 2°C; P = P – 10%) AVERAGE YEAR DRY YEAR

WHERE TO NOW? THE NEED TO ADAPT IN WATER RESOURCE MANAGEMENT

Acess to information Experiences of threat Sensitivity to threat AWARNESS OF THREAT External influences of regulations/ wealth -Government -CMAs/ Water Boards -State of economy Internal characterstics -Institutional capacity/ will Range of options -Demand -Supply -Culture -Expectations After Arnell (2005) INTENTION TO ADAPT ACTIVE ADAPTATION THE ADAPTATION PROCESS

Thresholds may decrease Variability may increase beyond thresholds Trends may shift beyond thresholds

DECISION FRAMEWORK ON CLIMATE VARIABILITY AND CLIMATE CHANGE TYPE OF DECISION CLIMATEWEATHER Long Term (10-50yrs)Medium Term (6-9mths)Short term (0-7days) Decadal ChangesSeasonal ForecastsReal Time → Week Strategic Tactical Operational Supply demand Reservoir safety Reservoir sizing Land management Operating rules Water orders Water allocation Demand management Irrigation scheduling Flood warning Field operations

TIME FRAMELEGAL AND POLICY INSTITUTIONAL AND MANAGEMENT MONITORING, RESEARCH AND INFORMATION LONG TERM Years to Decades (e.g. climate change) International National Water Resource Strategy National Climate Change Response Strategy More Specific Policy Requests Enforcing/Policing Policy Catchment Management Agencies Risk Management Governance Infrastructure Water Licencing Enforcement and Compliance MONITORING Networks and General Data RESEARCH General Capacity Building Climate Models Hydrological Modelling Specific Research Requirements INFORMATION Education/Training Communication S.A. ADAPTATION FRAMEWORK: CLIMATE CHANGE IMPACTS ON THE WATER SECTOR

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (a) Climate change also means land use change

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (b) Hydrological baselines against which SFRAs are levied, will shift [PMG note: graphics not incuded, please

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (c) “Hotspots” of climate change concern may need priority attention by DWAF

Runoff-Producing Stormflow Events are Projected to Change Implications: Lower inflows into reservoirs in certain areas Catchment sediment yields will change

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (d) Impacts of climate change on the water sector may be felt sooner than we like [PMG note: maps not incuded, please

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (e) Climate change impacts will be superimposed on already existing complex land use impacts [PMG note: maps not incuded, please

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (f) The ecological “Reserve” will be impacted

The aquatic environment is a LEGITIMATE water user and NOT a competing resource Upstream and downstream ecosystems management will have to adapt with climate change [PMG note: graphics not incuded, please

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (g) Health services will be impacted

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (h) Water quality will be impacted  Chemical  Physical  Biological [PMG note: graphics not incuded, please

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (i) Water availability to the poor will be impacted [PMG note: graphics not incuded, please

BUT... IS IT AS SIMPLE AS ALL THAT? NO, BECAUSE... (j) International water agreements with our neighbouring countries may have to be re-negotiated

THE TAKE-HOME MESSAGE.. Climate change is a global phenomenon, but the problems will be very local and we will need to adapt and plan