CLIMATE CHANGE AND WATER RESOURCES:

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CLIMATE CHANGE AND WATER RESOURCES CHALLENGES
AND QUESTIONS FOR THE D.W.A.F.
Roland Schulze Professor of Hydrology
School of Bioresources Engineering and
Environmental Hydrology University of
KwaZulu-Natal, Pietermaritzburg
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THE BASIC PREMISE . . . Climate change is a
global phenomenon, but the problems will be very
local and we will have to adapt and plan
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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
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- INTEGRATED IMPACT ASSESSMENT -

• Global

Regional
Local
Sectoral
agriculture
coastal
health
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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 email info_at_pmg.org.za
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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 email
info_at_pmg.org.za
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The Challenge GCM? RCM? QC? HRU PMG note
maps not incuded, please email info_at_pmg.org.za
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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
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Hillslope and Riparian Zone Processes in
ACRU (after Meier et al., 1997 Schulze, 2000b)
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Concepts, Processes and Assumptions in the ACRU
Wetlands Module (after Schulze et al., 1987 with
modifications by Schulze, 2001d)
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Schematic of Irrigation Water Demand and
Scheduling Options Available in ACRU (after
Schulze, 1995 and updates)
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WHAT HAVE FIRST RESULTS FROM THE W.R.C. PROJECT
ON CLIMATE CHANGE AND WATER RESOURCES IN SOUTH
AFRICA SHOWN?
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DETAIL EXPLODES FROM ANNUAL TO MONTHLY TO DAILY
VALUES TEMPERATURE PMG note maps not
incuded, please email info_at_pmg.org.za
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DETAIL EXPLODES FROM ANNUAL TO MONTHLY TO DAILY
VALUES RAINFALL PMG note maps not
incuded, please email info_at_pmg.org.za
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Potential Evaporation is Projected to Increase by
10 - 20
Implications Enhanced dam evaporation
losses Increased irrigation demands PMG
note maps not incuded, please email
info_at_pmg.org.za
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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 email info_at_pmg.org.za
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Fewer, but larger rainfall events may result in
more groundwater recharge PMG note maps not
incuded, please email info_at_pmg.org.za
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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 email
info_at_pmg.org.za


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Implications to Irrigation are Likely to be
Significant PMG note maps not incuded,
please email info_at_pmg.org.za


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WHAT COULD THIS IMPLY IN AN ACTUAL CATCHMENT
SITUATION? A case study from Swaziland
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MBULUZI CONFIGURATION
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Irrigation Local Supply
Irrigation Mnjoli Dam
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Irrigation Inter Basin Transfers
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Irrigation Multiple Sources
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Inter Basin Transfers
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Reservoir
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Streamflow Gauge
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8
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10
25
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Mnjoli
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32
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35
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POTENTIAL IMPACTS OF CLIMATE CHANGE, MBULUZI
CATCHMENT (Scenario T T 2C P P 10)
MNJOLI DAM OF FULL SUPPLY CAPACITY
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POTENTIAL IMPACTS OF CLIMATE CHANGE, MBULUZI
CATCHMENT (Scenario T T 2C P P 10)
MBULUZI OUTFLOWS TO MOZAMBIQUE
AVERAGE YEAR
DRY YEAR
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WHERE TO NOW? THE NEED TO ADAPT IN WATER RESOURCE
MANAGEMENT
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THE ADAPTATION PROCESS

Acess to information
AWARNESS

Experiences of threat
OF THREAT

Sensitivity to threat

External influences of regulations/ wealth
-
Government
INTENTION
-
CMAs/ Water Boards
TO ADAPT
-
State of economy

Internal characterstics
-
Institutional capacity/ will
ACTIVE
ADAPTATION

Range of options
-
Demand
-
Supply
-
Culture
-
Expectations
After Arnell (2005)
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Trends may shift beyond thresholds
Variability may increase beyond thresholds
Thresholds may decrease
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DECISION FRAMEWORK ON CLIMATE VARIABILITY
AND CLIMATE CHANGE
TYPE OF DECISION CLIMATE CLIMATE WEATHER
TYPE OF DECISION Long Term (10-50yrs) Medium Term (6-9mths) Short term (0-7days)
TYPE OF DECISION Decadal Changes Seasonal Forecasts Real 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

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S.A. ADAPTATION FRAMEWORK CLIMATE CHANGE IMPACTS
ON THE WATER SECTOR
TIME FRAME LEGAL 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
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BUT . . . IS IT AS SIMPLE AS ALL THAT?
NO, BECAUSE . . . (a) Climate change also means
land use change
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BUT . . . IS IT AS SIMPLE AS ALL THAT?
NO, BECAUSE . . . (b) Hydrological baselines
against which SFRAs are levied, will shiftPMG
note graphics not incuded, please email
info_at_pmg.org.za
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BUT . . . IS IT AS SIMPLE AS ALL THAT?
NO, BECAUSE . . . (c) Hotspots of climate
change concern may need priority attention by DWAF
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Runoff-Producing Stormflow Events are Projected
to Change
Implications Lower inflows into reservoirs in
certain areas Catchment sediment yields will
change
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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 email
info_at_pmg.org.za
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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
email info_at_pmg.org.za
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BUT . . . IS IT AS SIMPLE AS ALL THAT?
NO, BECAUSE . . . (f) The ecological Reserve
will be impacted
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The aquatic environment is a LEGITIMATE water
user and NOT a competing resource
Upstream and downstream ecosystems management
will have to adapt with climate changePMG
note graphics not incuded, please email
info_at_pmg.org.za
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BUT . . . IS IT AS SIMPLE AS ALL THAT?
NO, BECAUSE . . . (g) Health services will be
impacted
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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 email
info_at_pmg.org.za
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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 email info_at_pmg.org.za
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BUT . . . IS IT AS SIMPLE AS ALL THAT?
NO, BECAUSE . . . (j) International water
agreements with our neighbouring countries may
have to be re-negotiated
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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