Climate change and water resources in the South East of England An overview based on recent research CIWEM, Swindon, 18th May www.futuredrought.org.uk Steven Steven Wade, Wade, Jean-Philippe Jean-Philippe Vidal Vidal11 HR HR Wallingford Wallingford Acknowledgements: Acknowledgements: Defra Defra (Global (Global Atmospheres), Atmospheres), Environment Environment Agency, Agency, UKWIR, UKWIR, UKCIP, UKCIP, Project Project partners partners ~~ Met Met Office, Office, Lancaster Lancaster University, University, Entec Entec UK, UK, CRU, CRU, CEH, CEH, BGS, BGS, Anglian Anglian Water, Water, Southern Southern Water, Water, Veolia Veolia
Preamble: Why bother with climate change?
Water resources planning • EA WRPG Supplementary Guidance Note 1 states that the current approach is “appropriate …for the initial assessment of the impact of climate change. However it does not provide sufficient certainty for a major investment“
Drought risk management • Improved management of droughts to reduce demand, ensure supply and avoid damaging the environment
River Basin Management Plans Impacts on sewerage systems Catchment Flood Management Plans Regional Spatial Strategies/Sust. Communities Page 2
Preamble: Adapting to climate change (UK)
Government SD strategy theme “limiting and adapting to climate change” Adaptation Policy Framework, Treasury Review, UKCIP, EA policy For water resources management this means 1. Refinements to water resources planning, better drought risk management, etc… 2. Improvements in the wider planning system, building regulations etc…. Page 3
Preamble: Climate change in water resources
1. Can’t ignore climate change 2. Precautionary Principle - To ensure that decisions are taken notwithstanding scientific uncertainty about the nature and extent of the risk. 3. Alternative view - need:• Rigorous science • Practical solutions • Social engagement (Hunt, 2006) Page 4
Outline Introduction\Background Climate variability in the South East Impacts of climate change Rainfall drought River flows Reservoirs Groundwater Emerging issues from ongoing research Conclusions Page 5
Outline: Sources of information In presentation Within project scope All projects ongoing
Page 6
Impacts of climate change on
Project
Rainfall
River flow
Reservoir Groundwater Yield
EA Severe Droughts (CRU, UEA)
UKWIR/EA Effects of climate change….
Defra Cross-Regional R&D
Other (HR Wallingford funded)
Background: Water Availability & Supply
South East CEE
SEE
Water Availability (Groundwater): (Environment Agency, 2001). Page 7
Public Water Supply
Ground water
Surface Water
Anglian Water
50%
50%
Thames Water
25%
75%
Southern 80% Region
20%
Background: Water Availability (Surface Water) Summer
Page 8
Winter
(Environment Agency, 2001).
Background: 20th C rainfall comparison 61-90 average precipitation Annual Winter Summer Anglian
637
316
321
Thames
723
391
343
Southern
732
414
316
Lowest 1901-2000 precipitation Annual Yr Winter Anglian 365 1921 159
Yr 1976
Thames 420 Southern 397
1976 1976
Page 9
1921 1921
181 205
Summer Yr 1990 (1929/1959) 162 1990 (1921) 176 1921 159
Climate variation Variations in rainfall in the 20thth century and 19thth century (Anglian)
The development & impacts of UK drought Climate change
Climate variability
High temperatures Increased evapotranspiration
DURATION
Reduced ‘effective’ rainfall Less runoff and recharge Increase soil moisture deficits Lower groundwater levels Reduced river flow Reduced habitat areas
Plant water stress Reduced biomass/yield Increased demand for water
‘Threatened’ or actual water supply shortage Drought Permits/Orders Page 11
Environmental Impacts
Social Impacts
Economic Impacts
DROUGHT Rainfall--Agricultural-- Hydrological-- Water Resources
Rainfall deficits (amount, timing, severity)
Socio-economic change
Precipitation 20th C: Winter (Oct-March) Data from Environment Agency (Thames, Southern) & Anglian Water (Anglian)
% change from 61-90 average
60% 40% 20% 0% -20% 1944
-40%
1973
1934
1992
1976 -60% 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Southern Page 12
Thames
Year Anglian Southern
Thames
Anglian
Precipitation 20th C: Summer (April-Sept) Data from Environment Agency (Thames, Southern) & Anglian Water (Anglian)
% change from 61-90 average
80% 60% 40% 20% 0% -20%
1989
-40% 1959
1921
1990 1996 2003
-60% 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Year Page 13
Southern
Thames
Anglian
Southern
Thames
Anglian
Longer term precipitation for the Ouse (Osborn, Jones and Leadbetter, 2006 – EA Severe Droughts Project) Annual precipitation 40% 30% 20% 10%
-40% -50%
Period used for WRP
1998
1989
1980
1971
1962
1953
1944
1935
1926
1917
1908
1899
1890
1881
1872
1863
1854
1845
1836
-30%
-60%
Page 14
1827
-20%
1818
-10%
1809
0% 1800
% difference from 61-90 mean
50%
Longer term precipitation for the Ouse (Osborn, Jones and Leadbetter, 2005) Two year precipitation 20% 10%
98
89
19
80
19
71
19
62
19
19
19
53
44
35
19
26
19
17
19
08
19
99
19
90
18
81
18
72
18
63
18
54
18
45
18
36
18
27
18
18
18
09
18
-10%
18
00
0%
18
% difference from 61-90 mean
30%
-20% -30% -40%
Three year precipitation
Page 15
20% 10%
-20% -30%
98
89
19
80
19
71
19
62
19
53
19
19
44
19
35
19
26
19
17
19
08
19
99
18
90
81
18
72
18
63
18
18
54
18
45
18
36
18
27
18
18
09
18
-10%
18
00
0%
18
% difference from 61-90 mean
Point 1 – Past rainfall droughts were more severe than recent droughts – even without climate change severe droughts must be considered in forward planning
30%
Potential impacts of climate change Rainfall drought
Climate change uncertainty Uncertainty
Emissions Global Climate (GCM) Regional Climate (downscaling) Hydrological (data, structure, calibration) Page 17
Uncertainty
Climate change model uncertainties Ribble, NW
Rainfall Factor Indicators
15
UKCIP02 LOW
10
UKCIP02 MEDIUM UKCIP02 HIGH
5
HadCM3
0
CGCM2 CSIRO-mk2
-5
CCSR/NIES GFDL-R30
-10 -15 Average
Winter
Summer
ECHAM4/OPYC3
Spreadsheet of 2020s monthly rainfall and PET factors for all UK catchments (UKWIR/EA, 2006) Page 18
Climate change uncertainties e.g. Broadland Rivers (UKWIR, 2006) Monthly rainfall factors Percent change from 1961-90
40 30 20 10 0 -10 -20 -30 -40 Jan Feb Mar Apr May Jun Page 19
Jul
Aug Sep Oct Nov Dec
Development of extreme scenarios based on climate models (HR Wallingford, 2005)
NS ES
SS NI
NEE
NWE
CEE
SWE
Page 20
SEE
Direct use of monthly RCM data to estimate changes in frequency of severe droughts (6 months & 2 year) Regional analysis of 9 grid squares Comparison of GCM outputs (6 models) to place RCM in context Defra Cross-Regional Climate change programme
Changes in precipitation patterns based on HadRM3 Defra Cross-Regional Climate South East of England change programme Possible changes in precipitation 3 summer months (JAS) 200
Total rainfall July-Aug-Sept (mm)
180 160 140 120 100 80 60 40 20 0 1960
1970
1980
Control run 1961-1990 Page 21
1990
2000
2010
Low Emissions
2020
2030
2040
Medium High Emissions
2050
2060
2070
2080
High Emissions
2090
2100
Defra Cross-Regional Climate change programme
Changing patterns of seasonal rainfall 2080s Medium High Emissions scenario compared to 1961-1990
Change in frequency of extreme dry conditions
Page 22
East Scotland
South East England
1 in 20yr Dry Winter
23 yrs
18 yrs
1 in 10yr Dry Winter 1 in 20yr Dry Summer
12 yrs 9 yrs
10 yrs 7 yrs
1 in 10yr Dry Summer
5 yrs
4 yrs
Comments (--) No significant change
(x2) More dry summers
HadRM3 (A2) - Increase in the frequency of ‘short’ rainfall droughts Defra Cross-Regional Climate change programme
Number of 6 months extreme droughts
25
25
25
20
20
15
15
10
10
10
5
5
5
HadCM3 HadRM3-a HadRM3--b HadRM3--c
20 15
0
2020s 2050s NS
2080s
0
1970s
2020s 2050s ES
2080s
0
25
25
25
20
20
20
15
15
15
10
10
10
5
5
5
0
1970s
2020s 2050s NI
2080s
0
1970s
2020s 2050s NEE
2080s
0
25
25
25
20
20
20
15
15
15
10
10
10
5
5
5
0
Page 23
1970s
1970s
2020s 2050s CEE
2080s
0
1970s
2020s 2050s SWE
2080s
0
1970s
2020s 2050s SS
2080s
1970s
2020s 2050s NWE
2080s
1970s
2020s 2050s SEE
2080s
HadRM3 (A2) - Increase in the frequency of ‘long’ rainfall droughts Defra Cross-Regional Climate change programme
Number of 24 months extreme droughts 5
5
4
4
3
3
2
2
2
1
1
1
5 HadCM3 HadRM3-a HadRM3--b HadRM3--c
4 3
0
2020s 2050s NS
2080s
0
1970s
2020s 2050s ES
2080s
0
5
5
5
4
4
4
3
3
3
2
2
2
1
1
1
0
Page 24
1970s
1970s
2020s 2050s NI
2080s
0
1970s
2020s 2050s NEE
2080s
0
5
5
5
4
4
4
3
3
3
2
2
2
1
1
1
0
1970s
2020s 2050s CEE
2080s
0
1970s
2020s 2050s SWE
2080s
0
1970s
2020s 2050s SS
2080s
1970s
2020s 2050s NWE
2080s
1970s
2020s 2050s SEE
2080s
Potential impacts of climate change River flows
Runoff factors based on UKCIP02 scenarios for the 2020s (UKWIR, 2002) Anglian 5
% change
0 -5
J
F
M
A
M
J
J
A
S
O
N
D
-10 -15 -20 -25 -30 low
medium
high
Southern & Wessex
Thames 10
10
-10
J
F
M
A
M
J
J
A
S
O
-20 -30
D
0 -10
low
medium
high
J
F
M
A
M
J
-20 -30 -40 low
-40
Page 26
N
% change
% change
0
medium
high
J
A
S
O
N
D
Developing new runoff and recharge factors Consideration of climate model and hydrological uncertainties Seventy catchments selected for modelling Methods developed and tested on three case study catchments (Eden, Ribble and Thet) Modelling run in progress on a region by region basis UKWIR/EA CL-04 Page 27
Rainfall-runoff model structures PDM
Catchmod
Lumped conceptual model
Semi-distributed conceptual model
P
Rainfall Evapotranspiration
Direct percolation
Direct Runoff S2 Upper store
qs Surface Runoff
Lower store
E
Percolation
Penman soil moisture drying curve Actual E/t
Surface storage
g/1
1/1 Potential E/t
q Groundwater storage
Linear Store
qb Baseflow
Recharge S1
Non-Linear Store
S3 Runoff
Approach: building statistical distributions with behavioural UKWIR/EA CL-04 models from both model structures Page 28
Example results: Thet@MelfordBridge UKWIR/EA CL-04
Thet@Melfordb ridge: Bias Correction 50
90% confidence b ounds 50% confidence b ounds median
40
% Changes in monthly flows
30 20 10 0 -10 -20 -30 -40 -50 Page 29
J
F
M
A
M
J
J
A
S
O
N
D
Potential impacts of climate change Reservoirs
HadRM3H – perturbation to estimate source yields
Page 31
EA Severe Droughts Project
Potential impacts of climate change Groundwater
UKCIP02 Impacts on groundwater levels – Average changes in chalk in SE England (Bloomfield & Wade) 0.00 -0.20 -0.40 -0.60 -0.80 -1.00 Mean
-1.20
1 in 20 year
Page 33
Point 3 ditto
Scenario
H 20 80 s
L2 08 0s
H 20 80 s M
M
H 20 50 s
H 20 20 s
H 20 20 s M
M
L2 02 0s
-1.40 L2 02 0s
Change in groundwater level (metres)
Change in Minimum Groundwater Levels
Impacts summary & water resources issues Indicator Change in annual rainfall Change in summer rainfall (July-Aug) Change in winter rainfall (Dec-Feb) Change in mid summer PET Increase in the number of 6 month droughts every 30 years Change in mid summer river flows Reservoir schemes: Change in reservoir yields Chalk groundwater sources: reduction in groundwater levels Other factors Agricultural water requirements
Change (all models) -++
Change (UKCIP) 2020 2080s Low High -2% -11%
UKCIP02 (14 grid squares)
-10%
-51%
5%
25%
8%
45%
+
++
-25 to - 30% - 10 to 15% - 1%
n/a
- 5%
Bloomfield and Wade, forthcoming for UKCIP02 analysis. Very site specific.
+
+++
+
++
Impacts may be less irrigated area or investment in farm reservoirs or trading Changes in water quality, ecological status. Water Framework Directive.
n/a
Page 34
Environmental requirements
Source/Comments
UKCIP02 (14 grid squares). Decrease in most models UKCIP02 (14 grid squares). Increase in most models – good if storage available Increases in temperature and net (4) radiation . 3 to 4-fold increase by the 2080s based on direct use of HadRM3 outputs. So need resilience in system = storage or responsive behaviour. UKWIR 2006. Runoff factors wide ranging. Concern for summer abstractors (e.g. farmers). Will depend on catchment, license and source characteristics.
