European flooding from 1998-2007 caused 700 deaths and displaced 500,000 people with €25 billion in insured losses from 100 major floods from 1998-2002. From 2003-2007 there were 345 deaths and 120 major floods, resulting in €12 billion in insured losses. A catchment flood risk management plan was developed for the 121 square kilometer Dodder catchment area, which identified 1,467 properties at risk of flooding during a 1% annual exceedance probability flood event. The preferred flood risk management option identified was 1,683 meters of flood walls and 351 meters of flood embankments to protect the area from flooding. A strategic environmental assessment was conducted as part of the planning process.
2. European Flooding 1998 - 2002 2003 – 2007
Fatalities 700 345
Major Floods 100 120
Displaced people 500,000 -
Insured economic
Losses
€25 Billion €12 Billion
Figures from Emergency Disasters Database (EM-DAT)
2002 August (1:100 to 1:500 year event)
Czech Republic, Slovakia, Italy, Spain, Germany, Romania, Bulgaria, Croatia,
Hungary, and Ukraine
Vltava, Elbe and Danube rivers reached record highs
2005 August (>1:200 year event)
Romania, Germany, Austria, Moldovia, Switzerland, Poland Slovenia,
Serbia
Danube Rhine
3.
4. Catchment Flood Risk Management Plan (CFRMP)
Inception Report
Hydrology Report
Hydraulics Report
Preliminary Options Report
Urban Drainage Accommodation Report
Draft Final Report
Maintenance Report
Sediment transport model
Final Report
Strategic Environmental Assessment (SEA)
Appropriate Assessment (AA)
5. 121 sq. kilometres (47 sq.
miles)
Three LA’s DCC, SDCC and
DLRCC
Main Channel 19km d/s two
reservoirs
Tallaght Stream 5 km
Owendoher 10 km
Whitechurch 8 km
Little Dargle 8 km
Dundrum Slang 8 km
Tidal Region 2 km
Very steep with a history of
flooding (gradient 1:115)
6. Hydrometric Data
Survey data, property
registers
Environmental areas
Geotechnical surveys
Defence Asset Data
Flooding History
Previous studies
Individual Risk Receptors
(IRR), hospitals, fire
stations etc.
8. Review of historic Floods
Analysis of Hydrometric & Meteorological data
Estimation of design floods
Sensitivity tests for uncertainty
Climate change
Catchment changes
9. Build and verify hydraulic Model
Model runs for 2,5,10,25,50,100,200 &1000
years flows.
Sensitivity testing of model
Freeboard
10.
11. Development of historical flood maps
Developing flood extent (risk) maps for 10,
100 (200 tidal) and 1,000 year modelled
events (10%, 1% and 0.1% AEP)
Development of flood hazard maps
(properties, risk receptors & major
infrastructure under threat)
Defence failure scenario’s, protected areas
Risk analysis for Global Warming Scenario
15. Existing developed land
Development Plans for
each LA
Draft Development Plans
Local Plans
Area Plans
Other Plans (drainage,
etc.)
16. Do nothing
Tidal Barrage
Improvement to channel
conveyance
Relocation of properties *
Flood Warning system*
Culverting*
Diversion of watercourses
Catchment wide SuDS*
Proactive Maintenance
Reactive Maintenance
Overland Floodways
Public Awareness Campaign
Rehabilitation of existing
defences
Deculverting/ replacing
bridges
Individual property protection
Upstream Storage
Walls and Embankments
17. Core Criteria Objective
Economic
( 30%)
a
Ensure flood risk management expenditure is risk based
Benefit Cost Ratio, 10.0=+30%, 1.0=0%, 0.1=-30%.
Social
( 30%)
a Human Life. Minimise health and safety risk of flood risk management options
b Protect key infrastructure
c Protect existing, and where possible create new waterside access
and recreational and community facilities
d Maintain, and where possible increase, existing waterside access for fishing
Environmental &
Heritage
( 30%)
a Safeguard and promote sustainable land use in keeping with WFD
b
Support the achievement of good ecological status/good ecological potential (GES/GEP)
under the WFD. Particularly morphology as a supporting element to ecological status
c Protect the flora and fauna of the catchment and, where possible, enhance biodiversity,
Remove Alien Species
d Protect, and where possible enhance, fisheries within the catchment
e Protect, and where possible enhance, landscape character and visual amenity
f
Protect and where possible enhance known features of cultural heritage importance and
their settings
Technical
( 10%)
a
Ensure flood risk management options are operationally viable and to minimise
maintenance required.
b Ensure flood risk management options are technically and logistically viable
c Ensure flood risk managed effectively into the future
Other a No increase in flood risk to other areas
• Overall scenario must score positive to become viable option
• Benefit Cost Ratio ≥ 1
18. Strategic Environmental Assessment of
Dodder CFRAMS.
SI 436/2004 Planning & Development
(SEA) Regulations 2004, Revoke Art.6 of
2003 Regs.
Fall out of EU Regs 2001/42/EC.
19. Mammals
Six species of bat were found during the
preparation of the Dodder Habitats
Management Plan. These are;
•Pipistrelle (Pipistrellus pipistrellus)-
most frequently recorded,
•Soprano pipistrelle (Pipistrellus
pygmeaus),
•Leisler’s bat (Nyctalus leisleri),
•Daubenton’s (Myotis daubentonii),
•Brown Long-eared bat (Plecotus
auritus), and
•Whiskered/Brandt’s bats (Myotis
nysticanus/brandti).
20. Cormorant 1 Goosander 1 Sand Martin 3
Wigeon 1 Coot 1, 2 Swallow 3
Teal 1
Black-headed Gull
1
Spotted Flycatcher
1,3
Pochard 1 Common Tern 1 Redpoll 1
Tufted Duck 2 Kingfisher 1, 3
Amber List Species of Medium Conservation
Concern in Ireland recorded in the River
Dodder Conservation Area (adapted from
Newton et al., 1999).
21.
22. Assessment Unit Dodder AU, DS Donnybrook APSR
Water bodies Dodder
Preferred flood risk management option Hard Defences
Flood risk (1% AEP event)
The flood extent maps show that 1467 residential and commercial properties are at risk from flooding from the River Dodder during a 1% AEP
event. The hydraulic model shows that the flood risk is from a combination of out of bank flooding and overland flow.
Receiving Environment
Properties Utility Assets
(No)
Transport
Routes
(length km)
Agricultural Land
(hectares)
Social Amenity (No)
Residential
(No)
Commercial
(No)
1362 105 0 13.13 0 0
Other features and receptors
4 CSOs
11 listed monuments including water mills, bridges, religious sites, houses and enclosures
Land cover – discontinuous urban fabric, industrial and commercial units
Fishery habitat is good for all salmonid life stages throughout most of the Dodder system
No designated protected areas in the vicinity
Important areas of green space which are of significant ecological and natural heritage importance
WFD ecological status is poor
WFD objective is to restore to at least good status by 2021 (extension due to highly impacted sites)
This option consists of hard defences along the left and right bank of the River Dodder. The map shows an indicative line of the location and
extent of the flood defences that would protect the APSR during a 1% AEP event. The preferred option would involve the construction of
1,683m of flood walls and 351m of flood embankments averaging 1.2m above ground level.
Multi Criteria Analysis (MCA) Results
Benefit Cost Ratio (BCR) MCA scores
23.
24. Sent to EU with plan, SEA & AA statements.
Every 6 years subsequently
Major alteration(s) occurs in catchment