Climate change breakout group Chris Lambert Water Policy & Strategy Manager
UK Climate Projections 2009 (UKCP09) Projects changes over the century based on different levels of emissions 10 000 possible outcomes Probabilistic scenarios with wide range of possible changes Based on climate change models supported with expert opinion Climate change will affect: the demand for water water resources availability expressed as deployable output (DO) 2
What is Deployable Output? Measure of water resource availability Based on a dry year, and taking into account Thames Water s levels of service River Thames catchment vulnerable to a two year drought: 1921/22, 1933/34, 1943/44, 1975/76 Levels of service: Restriction Frequency Water use restrictions Level 1 1 year in 5 on average Intensive media campaign Level 2 1 year in 10 on average Sprinkler/unattended hosepipe ban Level 3 1 year in 20 on average Temporary Use Ban, Drought Permits, Ordinary Drought Order Level 4 Never Standpipes and rota cuts requiring an Emergency Drought Order 3
How do we use climate data to determine deployable output? WARMS: model examining frequency of restrictions, linked to water resource availability Uses daily rainfall, evaporation and flow data to model groundwater and river flows Climate of the last 90 years assumed to reflect the next 90 years Climate change impacts incorporated through: Varying historic rainfall and evaporation record to determine the impact on deployable output (DO) Uncertainty in estimates of DO captured through target headroom 4
How do we apply the data? HR Wallingford develop method for using UKCP09 data Approach applied to 2020s; application to 2030s in progress Historical droughts demonstrate River Thames catchment very sensitive to weather over the previous 12 months Aridity Index (AI) for previous 12 months good indicator of water resources drought AI and two stage sampling process used to select sub samples from UKCP09 data: coverage of UKCP09 specific drought conditions likely to cause water resource issues 5
How does climate change affect water supply? Method selects 100 representative samples AI selects even spread of 10 samples across data set; and a further 10 from the driest part of the distribution 20 samples used to derive monthly factors of rainfall, evaporation and river flow 6
How much water will be available? Rainfall, evaporation and flow factors input to WARMS to generate recharge scenarios for aquifers and evaluate impact on DO WARMS run 20 times to provide a range of total DO impacts Large deviation around linear trend we calculate a central estimate Impact of UKCP09 Climate Change Factors on JR10 London Base DO of 2175 Ml/d 2300 1 London DO (Ml/d) 2200 2100 2000 1900 1800 1700 1600 London Base DO = 2175Ml/d 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Weighting 1500 99 97 95 93 91 89 87 85 83 81 79 77 75 73 71 69 67 65 63 61 59 57 55 53 51 49 47 45 43 41 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 Drought Percentile London Base DO UKCP09 DO Weighting 7 5 3 1 0 7
What does UKCP09 mean in practice? Estimates of DO are uncertain water companies account for that through target headroom Climate change impacts of UKCP09 on London DO less than UKCIP02 250.0 Climate Change Impacts on London Supply Demand Balance Comparison between rdwrmp & UKCP09 200.0 150.0 Ml/d 100.0 50.0 0.0 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 Climate Change Impacts upon DO rdwrmp S8 Climate Change Uncertainty rdwrmp UKCP09 Mean Impact on DO UKCP09 DO Impact & TH Risk Updated 8
How does climate change affect water demand? We investigated impact of climate change on consumption Examined relationships with temperature, sunshine hours and patterns of rainfall Significant relationship between temperature, rainfall and pcc especially at times of peak demand 9
What does UKCP09 mean in practice? Impact of UKCP09 scenarios on dry year demand Date 2014/15 2019/20 2024/25 2029/30 2034/35 Demand 1.1 2.2 3.5 4.7 5.9 (Ml/d) 10
Conclusions Vast amount of data reduced to a representative and manageable sample method supported by Ofwat, EA and UKCIP Impact on water resource availability in 2020s reduced under UKCP09 in comparison to UKCIP02 and UKWIR06 Reduction in water resource availability would not significantly affect WRMP09 preferred programme Minimal impact of UKCP09 on demand 11
Breakout groups Demand forecasting led by David Spiller (Room: Motion 1) Climate Change led by Chris Lambert (Room: Motion 2) Re-use led by Siobhan O Neill (Room: Glide) 11.00 11.30 Stephen Bradley Lesley Inwards Simon Mills Karen Gibbs Paul Buckley Jen Heathcote Tora Hallatt Owen Davies Phil Burston Jayne Owen Ken Burgin Martin Lunn Chris Binnie Richard Brown Steve Wade Katharina Winbeck Sam Shean Neil Edwards Liz Cornwall Peter Vaughan Julia Gorman Dave Harvey 11.30 12.00 Rebecca Fenn-Tripp Martin Lunn Chris Binnie Richard Brown Peter Vaughan Sam Shean Neil Edwards Julie Gorman Dave Harvey Lesley Inwards Simon Mills Karen Gibbs Liz Cornwall Jen Heathcote Tora Hallatt Steve Wade Owen Davies Jayne Owen Rebecca Fenn-Tripp Ken Burgin Alex Nickson Katharina Winbeck Phil Burston 12
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