1. Modelling catchment sediment transfer: future sediment delivery to the Carlisle urban area Tom Coulthard Jorge A. Ramirez Paul Bates Jeff Neal

2. Blue, flood outline before, Red flood outline after....

3. Project Aims/Summary To model sediment delivery from the Eden catchment and how this can affect flooding in Carlisle Using CAESAR, to model morphological change in the Eden river catchment and Carlisle reach Use different climate & discharge records to simulate impact of climate and land cover change Transfer updated DTM to Bristol for hydraulic modelling

4. What is CAESAR? Catchment or Reach based cellular model Models Morphological Change Hydrological model – Adaptation of TOPMODEL Hydraulic model – Simple 2d steady state flow model Sediment transport – Bedload, 9 fractions using Wilcock & Crowe eqtn. – Suspended sediment, multiple fractions Slope Processes – Slope failure (landslips) – Soil Creep

5. Main Tasks Two modelling tasks: – 1. Model sediment and water from catchments draining into Carlisle – 2. Model morphological changes in Carlisle reach

6. 1. CAESAR catchment scale tasks Produce sediment output for the Eden river at Carlisle – Existing climate – Climate scenarios – Land cover change

7. Eden river sub-catchments 50m spatial resolution 6 sub-catchments Divisions coincide with flow gauges Km 25 Upper Eden Lower Eden Eamont Irthing Caldew Petteril Carlisle

8. Linking sub-catchments Carlisle Discharge Sediment Carlisle Erosion Deposition

9. Initial conditions: grain size distribution 40 sites visited 173 photographs taken of sediment on channel edge

10. Finer Sediment 20% Initial conditions: grain size distribution Photo analysis technique utilized to estimate individual grain sizes Grain size distributions per catchment/reach Grain size distributions all records Adjusted grain size distributions to add unmeasurable small grain sizes ( < 0.3mm )

11. Initial conditions: grain size distribution Grain Size (mm)Proportion Size 1.0630.10 Size 2.250.10 Size 310.12 Size 420.24 Size 540.21 Size 680.13 Size 7160.06 Size 8320.02 Size 91280.02

12. Climate change: What we wanted to do... Use UKCP09 weather generator to predict future rainfall Use rainfall predictions as divers for the CAESAR morphological model Generate sediment yields (and updated DEMs) for futures.

13. Upper Eden Climate Eamont Lower Eden Irthing Petteril Caldew 0 200,000 400,000 600,000 0 200,000 400,000 600,000 0 200,000 400,000 600,000 Time, hours Cumulative rainfall, mm 0 100000 200000 0 100000 200000

14. 75 year simulation 13 years of hourly rainfall repeated and amplified by climate factor – 13 years chosen as only continuous period across all catchments/raingauges – Climate factor increased by 10, 20 and 30% Record DEM’s and sediment outputs Catchment simulations

15. Petteril Caldew Lower Eden Irthing Eamont Upper Eden Catchment Sediment output 0 200,000 400,000 600,000 0 200,000 400,000 600,000 0 200,000 400,000 600,000 Time, hours 0 Cumulative sediment, m 3 0 1000000

16. 2. CAESAR reach scale tasks Produce future bed elevations for the Eden reach at Carlisle: Determine how this affects flood inundation

17. Water inputs Cumulative Discharge ( m 3 /sec) Eden Caldew Petteril Time, hours 0 200,000 400,000 600,000 0 20000000 30000000 10000000 Eden 84% Caldew 11% Petteril 5% Hourly Discharge

18. Sediment inputs Cumulative sediment, m 3 0 1000000 0 200,000 400,000 600,000 0 200,000 400,000 600,000 0 200,000 400,000 600,000 Time, hours Petteril Caldew Lower Eden 83% 12% 5% Eden Caldew Petteril Hourly lumped sediment

19. Changes in bed elevation -6m(Deposition) 6m(Erosion) +30% +10% Baseline +20%

20. LISFLOOD-FP 0 11 Depth, m reference DTM +30% Model formulation with inertia (Bates et al., 2010) 2D channel and floodplain. Normal depth at boundary with slope 0.0006 mm -1 (Horritt et al., 2010)

21. Bed elevations affect on flood levels 3 (more flooding) - 2 Difference in maximum water elevation (new – original) Baseline +20% +30% ∆ max water depth, m +10% (less flooding)

22. Previous trial runs (increasing sediment input) -6m( Deposition) 5m (Erosion ) Baseline -50% +50% +100%

23. Conclusions Morphological changes in the channel can have profound influences on inundation levels – relative to changes in flooding caused by climate change? Changes in flood level directly linked to erosion/deposition – Incision/aggradation alters conveyance Changes in channel pattern (cutoff) have a fairly profound affect on inundation patterns Relationship between discharge increase and changes in sediment yield is very site specific.. – Hard to apply a generic rule to all reaches

24. Aggradation in urban areas..