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ICE South West

20 June 2014

John Young

ISIS 1D Hydraulic Model

Hanham Avon

Hydraulic ModellingISIS model of the Floating Harbour Rivers Frome & Avon 

Frenchay, FromeAvonmouth Northern Stormwater

Interceptor

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Location

Avon CrescentNova Dam

Junction Lock & Underfall Yard 

Barthurst Dam

Mylne’s Culvert

Frome Culverts

Foss

Castle Park

Castle Ditch

Totterdown Dam& Victor Street

Forgotten Lock

NethamWeir, Sluices & Sheet Piles

1D / 2D ISIS – TUFLOW Modelling

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Tidal Inundation (2012)

Existing Defence Configuration

Return Periods1 in 200 : Tidal / Surge

1 in 10 : Avon1 in 10 : Frome

Tidal Inundation (2035)

Existing Defence Configuration

Return Periods1 in 200 : Tidal / Surge

1 in 10 : Avon1 in 10 : Frome

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Tidal Inundation (2060)

Existing Defence Configuration

Return Periods1 in 200 : Tidal / Surge

1 in 10 : Avon1 in 10 : Frome

Tidal Inundation (2115)

Existing Defence Configuration

Return Periods1 in 200 : Tidal / Surge

1 in 10 : Avon1 in 10 : Frome

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Number of Flooded Properties (2012)

T= varies, A =10, F=10

Number of Flooded Properties (2012 ‐ 2112)

T= 200, A =10, F=10

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Condition Prognosis, Operation & Flooding

Avon Crescent, Underfall Yard / Nova Dam & Junction Lock

Junction Lock

Flood Gate

Underfall Yard Sluices Culverts

& Outfall

Avon Crescent

Nova Dam

Avon CrescentNova Dam

Junction Lock & Underfall Yard 

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Junction Lock8.20m AOD 8.751m AOD

Dockside Level

210020602011

Flood Gate

1.1m 1.6m

Avon Crescent

T= 50, A =10, F=10

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Cumberland Road8.30m AOD

Cumberland Road

210020602011

9.15m AOD

Electricity Sub-Station

6.80m AOD

1.0m 1.5m

Bathurst Dam & Lock

Dam Constructed in 1953

Barthurst Dam

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Bathurst Basin

T= 50, A =10, F=10

Totterdown Lock and Dam

1750 1828

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St Phillips

T= 50, A =10, F=10

Fluvial Flows

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Climate Change AdaptationYear(s) Climate Change Adaptation Example of adaptation

2012 Prepare Flooding Project Appraisal Study for Floating Harbour

2012 Develop & implement Flood Management Plan (via Project Appraisal Study)

Lowering water levels in the harbour based on reaction to flood forecasting

2012 Preparation of Flood Resilience Plan & Strategy (via Project Appraisal Study)

Evaluate flood resilience of MEICA systems at Underfall Yard & Cumberland basin

2013‐2015 Implement Flood Resilience Strategy Improve security of power supply to Underfall Yard Sluices

2015 Construct flood defences Cumberland Road & Avon Crescent

2015 Install additional pumping capacity to address surface water flooding

2012‐ 2025 Planning for the implementation of a barrage scheme

2025‐2035 Construct storm surge barrier on the Avon

1 Dimensional ISIS Modelling

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ISIS 1D Hydraulic Model

Frenchay, FromeAvonmouth Northern Stormwater

Interceptor

AV4

Blackrock

Avon Barrier ‐ Section Locations

AV4

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Avonmouth – Tides & Surge

Avonmouth Htbdy.xlxs

Surge Profile

1 in 200 Factored Surge Profile

Tidal Profile

1 in 200 year HT bdy = Factored Surge Profile + Tidal Profile9.11m AOD

Avonmouth – Tides & Surge

Close Barrierto tidal Inundation (close to low tide to maximise storage volume in Avon)

Open Barrier to allow fluvial water temporally stored in Avon upstream of barrier to drain

Close Barrierto tidal Inundation (close to low tide to maximise storage volume in Avon)

Open Barrier to allow fluvial water temporally stored in Avon upstream of barrier to drain

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The EVY calibre program used the genetic algorithm to gradually improve the ISIS models towards a set of predefined criteria (peak water levels) by varying the timing and of gate operations over a range of tidal cycles.

Barrier Operation

Calibre ‐ Shapes

Decide Input Shapes to Genetic 

AlgorithmWater Level in River Avon

Assign a level of importance to each shape by applying  a weighting

Water Level in Floating Harbour

Water Level in River Frome

combined into a single “model quality” 

number

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Calibre Events

Avon & Chew Frome Tide Climate Change

1:2 (2yr) 1:10 (10yr)1:200 (200yr)

25 years time

1:2 (2yr) 1:10 (10yr)

1:10 (10yr) 1:5 (5yr)1:20 (20yr)

1:20 (20yr) 1:50 (50yr)

1:100 (100yr) 1:100 (100yr) 1:2 (2yr)

1:2 (2yr) 1:2 (2yr)1:200 (200yr)

100 years time

1:10 (10yr) 1:10 (10yr)

1:10 (10yr) 1:5 (5yr)1:20 (20yr)

1:20 (20yr) 1:50 (50yr)

1:100 (100yr) 1:100 (100yr) 1:2 (2yr)

Calibre – The fun starts

The ISIS model is run for a range of events/ Return Periods

Preliminary operating regime is defined for the Barrier

i.e. timing of barrier

operation opening &

closing

Calibre randomly adjusts, by a small amount, the operating 

regime of the barrier to create 8 “child” models.

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Calibre – The fun carries on

The ISIS model is run for a range of events on the Avon, Frome, Chew 

and Tidal/Surge 

Model Quality Numbers Extracted and 4 Parent Models Selected 

The “next generation” operational rules are then jiggled twice by applying a 

random mutation to create 8 child models within this generation

Calibre The results for each gauge/event are compared to the specified levels and flows. These are weighted and the results combined into a single “model quality” number.

The best four models are selected and these are averaged and combined in pairs to create four new “next generation” operational rules. 

The “next generation” operational rules are then jiggled twice by applying a random mutation to create 8 child models within this generation.

The model iterates until it is aborted by the user.

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Impact of Barrier Optimisation

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