Flash Floods in a changing context:
Importance of the impacts induced by a changing environment
Table of contents
•Sub Project 5
•Review of current practices & pastexperiences
•Future scenarios
•Future risk assessment
•Mitigation and adaptation
•Conclusions
Sub project 5
FF & DF risk management and mitigation inchanging environments
•Review of current practices & past experiences
•Creation of global change scenarios
▫Climate
▫Land-use
▫Forest fires
•Development of a methodologies to assess theimpacts future changes
▫Risk mapping
▫Rule-based system
•Provide guidelines for practitioners to designmitigation and adaptation measures
Review of current practices & past experiences
Compilation of FF & DF follow-up studies
•Description of impacts
•Improvements on the local risk management
•Compilation of lessons learnt classified by
▫Prevention
▫Preparedness
▫Response
▫Dissemination and education
Prevention
Risk estimation
Land use regulations
Hydrometeorological forecasting systems
Integral analysis to plan protection infrastructures
Infrastructure inventory (maintenance)
Natural floodplains (water retention)
Historical FF and DF databases (learn from past)
Future changes (i.e. climate and land use)
Prevention
Risk estimation
Land use regulations
Hydrometeorological forecasting systems
Integral analysis to plan protection infrastructures
Infrastructure inventory (maintenance)
Natural floodplains (water retention)
Historical FF and DF databases (learn from past)
Future changes (i.e. climate and land use)
Preparedness
Review and update emergency plans (real effectiveness)
River bed maintenance
Evacuation maps
Training and plan evacuation simulations
Preparedness
Review and update emergency plans (real effectiveness)
River bed maintenance
Evacuation maps
Training and plan evacuation simulations
Response
Coordination of organizations involved
Unit to monitor the post-crisis
Follow-up studies
Improve warnings transmission
Promote hydrometeorological systems
Continuous maintenance
Response
Coordination of organizations involved
Unit to monitor the post-crisis
Follow-up studies
Improve warnings transmission
Promote hydrometeorological systems
Continuous maintenance
Dissemination and education
Exchange between experts
Diversify the mechanisms to disseminate
Risk culture:
o sociological surveys
o flood marks
o hazard maps
o …
Education programmes at schools
Dissemination and education
Exchange between experts
Diversify the mechanisms to disseminate
Risk culture:
o sociological surveys
o flood marks
o hazard maps
o …
Education programmes at schools
Creation of global change scenarios
•Future climate scenarios
▫Extreme precipitation assessment
•Future land-use scenarios
▫Urban land-use
▫Rural land-use
•Future forest fires scenarios
Future climate scenarios
Llobregat basin
•Data used
•Models validation
•Temporal future trends
•Future spatial patterns
Institution
Downscalingmethod
Model
Outputresolution
SRESscenarios
Controlperiod
Futurescenarios
GCM
RCM
SMC
Dynamical
ECHAM5-MPIOM
MM5
15 km, 6h
A2, B1
1971 - 2000
2001 - 2100
Observations
Altava-Ortiz
3 km, daily
1971 - 2000
MPI-MET
Dynamical
ECHAM5-r3
REMO
25 km, daily
A1B
1961 - 2000
2001 - 2100
METO-HC
Dynamical
HadCM3Q0
HadRM3Q0
25 km, daily
A1B
1961 - 2000
2001 - 2100
Observations
Spain 02
20 km, daily
1950 - 2003
GEV fitted to the annual maxima daily precipitation for theobservations (1971-2000), the control (1971-2000) (dashed)and the climate models results (1971-2100) (solid) showingthe minimum and maximum intensity in the Llobregat basin
Extreme precipitation assessment
•Generalized Extreme Value functions
•Future scenarios; periods of 30 years
•High variability and uncertainty
Future climate scenarios
GEV fitted to the annual maxima daily precipitation for thecontrol (1971-2000) and future periods simulated with SMC forthe A2 scenario in the south Llobregat basin
Future land-use scenarios
Urban land-use
•Corine database
•JRC’s MOLAND model
Urban land-use maps in the south Llobregat basin coming from Corine database (2000)and MOLAND A2 future scenario (2040)
Future land-use scenarios
Rural land-use
•Eururalis project data
Llobregat 2000
Llobregat 2030 A1
Llobregat 2030 A2
Llobregat 2030 B1
Llobregat 2030 B2
Forest fires scenarios
Canadian Drought Code
•Depends on T and P
•Validation with actual forest fires
•Daily calculation of CDC > 400
Annual CDC computed on the Llobregat basin during thehistorical period. The highest value occurred in 1994when the most significant forest fire occurred.
Historical and future scenarios of CDC on the Llobregat basin based on observations and SMC climate scenario A2 for three time periods
Future risk assessment
Risk = Hazard x Exposure x Vulnerability
Low Llobregat basin, showing the floodplains for a 500 year return period event.
Llobregat basin I – T relationship for a 24 h duration forthe A2 SRES scenario, for the control period and the futurescenario 2040.
Weighing function to update the hazard values for thefuture rainfall scenarios.
Future risk assessment
Risk = Hazard x Exposure x Vulnerability
Urban land use in the Low Llobregat area: Urban land use from Corine 2000 (a); and A2 urban landuse scenario for 2040 (b).
Vulnerability map for the A2 land usescenario for 2040.
Future risk assessment
•Overlaying the three variables and multiplying the weights
Vulnerability
Hazard
6
5
4
3
2
1
135
810
675
540
405
270
135
69
414
345
276
207
138
69
65
390
325
260
195
130
65
45
270
225
180
135
90
45
42
252
210
168
126
84
42
18
108
90
72
54
36
18
Risk maps for the south Llobregat basin for the (a) current situation (2000), (b) future A2 – A2 scenario (2040) (c) and its difference
Rule based system
•Forecasting system that allows to link real-timeobserved values with expected hazard in probabilisticterms
▫Simplification of a hydrological model with shorter leadtimes
▫Operational use: issue warnings
▫Considering high percentiles to represent extreme events
•Governing variables for FF
▫Antecedent soil moisture
▫Forecasted rainfall
Rule based system
•Anoia basin
▫Ocurrence
Moderate increase
Two exceptions
▫Intensity
Generalized increase
Even for the exceptions
Period
# POT per year (for each sub-period)
Control(1980-2009)
0.86
2011-2040
2041-2070
2071-2100
Scenario A2(2011-2100)
0.93
0.93
0.53
Scenario B1(2011-2100)
0.80
1.07
0.87
GP distribution fitted to the POT discharge values of the Anoia sub-basin for thecontrol (1980-2009) and future periods for the A2 (left) and B1 (right) scenarios.
Time series of the discharge values in the Anoia sub-basin.
Mitigation and adaptation
•Important changes may occur, but uncertaintiesare high and difficult to assess
•Change of paradigm must be done:
▫From «Fighting against Floods» to «Living with floods»
Mitigation and adaptation
•Implementation of EC Floods Directive anddevelopment of FRMP is crucial
▫Promoting communication and creating a risk culture
▫Implementing non-structural measures, which arerobust and win-win
Early warning systems
SUDS
Local mitigation strategies (involving the population)
Etc.
Conclusions
•Climate projections strongly depend on models
▫Need for further research
▫Regionalized models are crucial
•High variability and uncertainties
▫Present everywhere
▫Specially for extremes
▫Use results with care
•Mitigation and adaptation
▫Implementation of EC Floods Directive is crucial
▫Change of paradigm is needed
▫Non-structural measures must be used
