Planning for an uncertain future has always been a difficult task. The complexity of the issue lies not only in climate projections, but also on how climate risks propagate through the hydrological system. In the UK, water companies outline key uncertainties of water planning in their Water Resource Management Plan, as required by the Environment Agency (EA, 2008). The plan presents a baseline projection of supply-demand balance for a 25-year horizon. Options to maintain a healthy water balance is implemented in a “predict-then-act” approach, that is, when water deficits are likely to occur. Yet, the system can be locked to inflexible options and remains vulnerable to surprise factors. This study proposes a scenario-analysis-based approach that emphasizes flexibility and adaptability. This poster presents a preliminary assessment of options as proposed by Southern Water for the Sussex Area. It is conducted based on the necessity of extending option analysis, in views of uncertainty in climate risks and socio-economic responses. •Most of the feasible measures on the demand side has a lower WAFU than those on the supply side •If all options were implemented, the region could have an additional yield of 119 Ml/day (ignoring the interactions among options), compared to the current chosen option of Southern Water(11.5 Ml/d). These options appear to be sufficient to cope with future water deficit, unless the deficit occurs in the first circle (2010-2015). Yet, when overlapping options are eliminated, the maximum attainable WAFU is 60 Ml/day (Figure 3). •The linear correlation between extra WAFU and cost suggests that an extra Ml/day of WAFU entails a relatively-fixed cost. This applies to all the case, from selecting one option to all options. Overall, the impacts of supply measures are much more substantial than those of demand measures. The implementation time and the variability in effects of the supply measures are vital, particularly once cost is concerned. A robust sample of all scenarios is likely to produce a comprehensive analysis of options than the “predict-then-act approach”. The study acts as the base for further stages of the study, in which a water balance model will be used to simulate the influence of uncertainties on system resilience and robustness. The next stage of the study is proposed to be •To implement climate projections into hydrological analysis of the system •To analyse options based on hydrological and socio- economic settings of the region •To identify packages of robust measures that can enhance system resilience to droughts Lan Hoang, Suraje Dessai, and Richard Brazier College of Life and Environmental Sciences Amory Building, Rennes Drive, University of Exeter, Exeter EX4 4RJ, United Kingdom •To demonstrate an alternative option appraisal to the “predict-then-act” approach •To highlight the need to better characterize uncertainty in water resource planning With special thanks to Southern Water, CLES (Exeter University) and other project partners. This project is supported by EPSRC and ARCC-Water Project. Figure 2. Graph of baseline if all feasible options and preferred option are implemented Figure 1. Schematics of Sussex supply system, based on Southern Water’s Water Resource Management Plan (2009) Introduction Methodology Aims Results and Discussion Conclusion Acknowledgements References Environment Agency (2008). Water Resource Planning Guideline. Southern Water (2009). Water Resources Management Plan. Final Report. SOUTHERN WATER Portsmouth Water South East Water Sussex Worthing Sussex Brighton Sussex North Hardham Treament Plan Weirwood Reservoir OPTION REFERENCE No. WAFU ON FULL IMPLEMENTATION (Ml/d) EARLIEST POTENTIAL OPTION START DATE (YEAR) A 0.051 2027 B 0.019 2010 C 0.073 2038 D 0.022 2010 E 0.038 2010 F 0.061 2038 G 0.003 2010 H 0.026 2010 I 0.330 2023 J 0.041 2038 K varies 2010 L varies 2011 M 0.2 2015 The procedure of scenarios analysis was as follows Part 1: Combinations of options were randomly selected from the option set, ignoring their interlinks. Total extra WAFU and associating costs would then be calculated. Part 2: The excludability of options were considered. In essence, the group of options N7, N9 and NR2 can only have one representative. This result was then compared to the previous case. 1. The study area consists of North Sussex, Sussex Worthing and Sussex Brighton, as depicted in figure 1. Climate change impacts were considered to start manifesting in the region in 2017 for North Sussex and 2015 for Worthing and Brighton. This poster presents the analysis on Sussex North. Options being considered include those from the demand and supply sides, such as universal metering, leakage reduction, inter-regional transferring scheme and enhancing river abstraction (Southern Water, 2009) (refer to Table 1 and 2) Table 1. Feasible Options on the Demand Side, based on Southern Water’s Water Resource Management Plan (2009) Table 2 Feasible Options on the Supply Side, based on Southern Water’s Water Resource Management Plan (2009) OPTION REFERENCE No. WAFU ON FULL IMPLEMENTATION (Ml/d) EARLIEST POTENTIAL OPTION START DATE (YEAR) N1 0.5 2013 N3 3.0 2012 N4 3.0 2012 N5 12.0 2017 N6a 17.5 2020 N6a 21.0 2020 N7a 4.0 2012 N7b 7.5 2012 N7c 9.5 2013 N9 10.0 2012 NR2 15.0 2016 NR2 15.0 2016 For more information, please refer to the project website www.arcc-water.org.uk 2. Methods The analysis was based on baseline and options detailed in the Water Resource Table of Southern Water., in particular the extra Water Available for Use (WAFU) and cost of each option. In this study, the Dry Year Scenario (of Deployable Output) was considered . Figure 3. Water Available for Use versus the total cost to attain that WAFU in the case of a) All options are considered and b) Dependent options are eliminated. The sets of low WAFU, low cost are mainly demand options. Their impacts are relatively small compared to those of supply options. Meanwhile, those at the high WAFU, high cost end are combinations of all options, but still dominated by the impacts of demand options. In general, the lower front of the clusters in Figure 3 forms a Pareto front of options with a lowest cost for each WAFU threshold. However, this front does not constitute the most reliable and resilient options.
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Planning for an uncertain future has always been a difficult task. The complexity of the issue lies not only in climate projections, but also on how climate risks propagate through the hydrological system.
In the UK, water companies outline key uncertainties of water planning in their Water Resource Management Plan, as required by the Environment Agency (EA, 2008). The plan presents a baseline projection of supply-demand balance for a 25-year horizon. Options to maintain a healthy water balance is implemented in a “predict-then-act” approach, that is, when water deficits are likely to occur. Yet, the system can be locked to inflexible options and remains vulnerable to surprise factors. This study proposes a scenario-analysis-based approach that emphasizes flexibility and adaptability.
This poster presents a preliminary assessment of options as proposed by Southern Water for the Sussex Area. It is conducted based on the necessity of extending option analysis, in views of uncertainty in climate risks and socio-economic responses.
•!Most of the feasible measures on the demand side has a lower WAFU than those on the supply side •!If all options were implemented, the region could have an additional yield of 119 Ml/day (ignoring the interactions among options), compared to the current chosen option of Southern Water(11.5 Ml/d). These options appear to be sufficient to cope with future water deficit, unless the deficit occurs in the first circle (2010-2015). Yet, when overlapping options are eliminated, the maximum attainable WAFU is 60 Ml/day (Figure 3). •!The linear correlation between extra WAFU and cost suggests that an extra Ml/day of WAFU entails a relatively-fixed cost. This applies to all the case, from selecting one option to all options.
Overall, the impacts of supply measures are much more substantial than those of demand measures. The implementation time and the variability in effects of the supply measures are vital, particularly once cost is concerned. A robust sample of all scenarios is likely to produce a comprehensive analysis of options than the “predict-then-act approach”.
The study acts as the base for further stages of the study, in which a water balance model will be used to simulate the influence of uncertainties on system resilience and robustness.
The next stage of the study is proposed to be
•!To implement climate projections into hydrological analysis of the system
•!To analyse options based on hydrological and socio-economic settings of the region •!To identify packages of robust measures that can enhance system resilience to droughts
Lan Hoang, Suraje Dessai, and Richard Brazier College of Life and Environmental Sciences
Amory Building, Rennes Drive, University of Exeter, Exeter EX4 4RJ, United Kingdom
•!To demonstrate an alternative option appraisal to the “predict-then-act” approach
•!To highlight the need to better characterize uncertainty in water resource planning
With special thanks to Southern Water, CLES (Exeter University) and other project partners. This project is supported by EPSRC and ARCC-Water Project.
Figure 2. Graph of baseline if all feasible options and preferred option are implemented
Figure 1. Schematics of Sussex supply system, based on Southern Water’s Water Resource Management Plan (2009)
Introduction
Methodology
Aims
Results and Discussion Conclusion
Acknowledgements
References Environment Agency (2008). Water Resource Planning Guideline.
Southern Water (2009). Water Resources Management Plan. Final Report.
SOUTHERN WATER Portsmouth Water
South East Water
Sussex Worthing
Sussex Brighton
Sussex North
Hardham Treament
Plan
Weirwood Reservoir
OPTION REFERENCE No.
WAFU ON FULL IMPLEMENTATION
(Ml/d)
EARLIEST POTENTIAL OPTION START DATE
(YEAR) A 0.051 2027
B 0.019 2010
C 0.073 2038
D 0.022 2010
E 0.038 2010
F 0.061 2038
G 0.003 2010
H 0.026 2010
I 0.330 2023
J 0.041 2038
K varies 2010
L varies 2011
M 0.2 2015
The procedure of scenarios analysis was as follows
Part 1: Combinations of options were randomly selected from the option set, ignoring their interlinks. Total extra WAFU and associating costs would then be calculated.
Part 2: The excludability of options were considered. In essence, the group of options N7, N9 and NR2 can only have one representative. This result was then compared to the previous case.
1. The study area consists of North Sussex, Sussex Worthing and Sussex Brighton, as depicted in figure 1. Climate change impacts were considered to start manifesting in the region in 2017 for North Sussex and 2015 for Worthing and Brighton. This poster presents the analysis on Sussex North. Options being considered include those from the demand and supply sides, such as universal metering, leakage reduction, inter-regional transferring scheme and enhancing river abstraction (Southern Water, 2009) (refer to Table 1 and 2)
Table 1. Feasible Options on the Demand Side, based on Southern Water’s Water Resource Management Plan (2009)
Table 2 Feasible Options on the Supply Side, based on Southern Water’s Water Resource Management Plan (2009)
OPTION REFERENCE No.
WAFU ON FULL IMPLEMENTATION
(Ml/d)
EARLIEST POTENTIAL OPTION START DATE (YEAR)
N1! 0.5 2013 N3! 3.0 2012 N4! 3.0 2012 N5! 12.0 2017 N6a! 17.5 2020 N6a! 21.0 2020 N7a ! 4.0 2012 N7b ! 7.5 2012 N7c! 9.5 2013 N9! 10.0 2012
NR2! 15.0 2016 NR2! 15.0 2016
For more information, please refer to the project website www.arcc-water.org.uk
2. Methods The analysis was based on baseline and options detailed
in the Water Resource Table of Southern Water., in particular the extra Water Available for Use (WAFU) and cost of each option. In this study, the Dry Year Scenario (of Deployable Output) was considered .
Figure 3. Water Available for Use versus the total cost to attain that WAFU in the case of a) All options are considered and b) Dependent options are eliminated.
The sets of low WAFU, low cost are mainly demand options. Their impacts are relatively small compared to those of supply options. Meanwhile, those at the high WAFU, high cost end are combinations of all options, but still dominated by the impacts of demand options. In general, the lower front of the clusters in Figure 3 forms a Pareto front of options with a lowest cost for each WAFU threshold. However, this front does not constitute the most reliable and resilient options.
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