Transcript CLIMATE CHANGE AND WATER RESOURCES: CHALLENGES

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
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, crosscutting one
- INTEGRATED IMPACT ASSESSMENT Global
Regional
Local
Sectoral
coastal
agriculture
health
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 [email protected]]
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 [email protected]]
The Challenge: GCM RCM QC HRU
[PMG note: maps not incuded, please email [email protected]]
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
Sustainable,
Efficient, Beneficial
Water Use
Redressing Past
Inequities
Meeting
International
Obligations
Basic Human Needs:
Present, Future
Equitable Access
to Water
N.W.A.
TAKES
INTO
ACCOUNT
Promoting Dam
Safety
Socio-Economic
Development /
Future Demands
Reducing Water
Pollution,
Degradation
Managing
Floods, Droughts
Protection of
Ecosystems,
Biodiversity
Demand Management
Crisis Management
Environment Management
Socio-Political Management
RES2269
Hillslope and Riparian Zone Processes in
ACRU
(after Meier et al., 1997; Schulze, 2000b)
Commercial Forest 1
Grassland
2
3
Grassland
4
Other
5
Grassland
6
Riparian
1
4
2
Qs
3
5
6
6
Qs
Qs
Qs
Qb
Qb
Qb
Qb
Qb
5
Concepts, Processes and Assumptions in
the ACRU Wetlands Module
(after Schulze et al., 1987; with modifications by Schulze, 2001d)
UPSTREAM
INFLOWS
VARIABLE AREA OF
WATER SURFACE
OPEN WATER
EVAPORATION
TRIBUTARY
INFLOWS
CHANNEL STORAGE
AND ROUTING
DRAINAGE AND
ABSTRACTIONS
TOTAL
EVAPORATION
PERIODICALLY
SATURATED
TOPSOIL HORIZON
SATURATED
SUBSOIL HORIZON
WETLAND SPILLWAY
IMPERVIOUS LAYER
VARIABLE
WATER-SOIL
INTERFACE
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 email [email protected]]
DETAIL “EXPLODES” FROM ANNUAL TO
MONTHLY TO DAILY VALUES: RAINFALL
[PMG note: maps not incuded, please email [email protected]]
Potential Evaporation is Projected to Increase
by 10 - 20%
Implications: Enhanced dam evaporation losses
Increased irrigation demands
[PMG note: maps not incuded, please email [email protected]]
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 [email protected]]
Fewer, but larger rainfall events may result in
more groundwater recharge
[PMG note: maps not incuded, please email [email protected]]
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 [email protected]]
Implications to Irrigation are Likely to be
Significant
[PMG note: maps not incuded, please email [email protected]]
WHAT COULD THIS IMPLY
IN AN ACTUAL
CATCHMENT SITUATION?
A case study from Swaziland
MBULUZI : CONFIGURATION
1
2
Irrigation – Local Supply
Irrigation – Mnjoli Dam
3
Irrigation – Inter Basin Transfers
4
Irrigation – Multiple Sources
5
Inter Basin Transfers
6
21
Reservoir
7
12
8
22
Streamflow Gauge
9
14
23
11
10
16
13
25
15
Mnjoli
24
26
18
17
19
32
20
34
27
28
29
30
31
33
35
36
37
38
39
40
POTENTIAL IMPACTS OF CLIMATE CHANGE, MBULUZI CATCHMENT
(Scenario: T = T + 2°C; P = P – 10%)
MNJOLI DAM: % OF FULL SUPPLY CAPACITY
120
100
Present: %FSC,
1:2 Med
80
AVERAGE
YEAR
60
Future: %FSC,
1:2 Med
40
20
0
J F M A M J J A S O N D
60
50
DRY
YEAR
Present: %FSC,
1:10 Dry
40
30
Future: %FSC,
1:10 Dry
20
10
0
J F M A M J J A S O N D
POTENTIAL IMPACTS OF CLIMATE CHANGE, MBULUZI CATCHMENT
(Scenario: T = T + 2°C; P = P – 10%)
MBULUZI OUTFLOWS TO MOZAMBIQUE
25
20
AVERAGE
YEAR
15
Present:
Median
10
Future:
Median
5
0
J
DRY
YEAR
F
M
A M
J
J
A
S O
8
7
6
5
4
3
2
1
0
N
D
Present 1:10 Dry
Future 1:10 Dry
J F M A M J J A S O N D
WHERE TO NOW?
THE NEED TO ADAPT IN
WATER RESOURCE
MANAGEMENT
THE ADAPTATION PROCESS
• Acess to information
• Experiences of threat
• Sensitivity to threat
AWARNESS
OF THREAT
INTENTION
TO ADAPT
• External influences of regulations/ wealth
- Government
- CMAs/ Water Boards
- State of economy
• Internal characterstics
- Institutional capacity/ will
ACTIVE
ADAPTATION
After Arnell (2005)
• Range of options
- Demand
- Supply
- Culture
- Expectations
Trends may shift beyond thresholds
Variability may increase beyond thresholds
Thresholds may decrease
DECISION FRAMEWORK ON CLIMATE VARIABILITY AND
CLIMATE CHANGE
CLIMATE
TYPE OF
DECISION
WEATHER
Long Term (10-50yrs)
Medium Term (6-9mths)
Short term (0-7days)
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
S.A. ADAPTATION FRAMEWORK:
CLIMATE CHANGE IMPACTS ON
THE WATER SECTOR
TIME FRAME
LONG TERM
Years to Decades
(e.g. climate change)
LEGAL AND
POLICY
INSTITUTIONAL
AND
MANAGEMENT
MONITORING,
RESEARCH AND
INFORMATION
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
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 email [email protected]]
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 email [email protected]]
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 [email protected]]
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 email [email protected]]
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 email [email protected]]
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 [email protected]]
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