Environmental Engineering Reference
In-Depth Information
where flood riskmanagement is now, but where it
may be going in the future.
.
. Evidence based: Flood riskmanagement is often
dealing with situations and scenarios that have
never occurred in practice. It relies therefore on
statistical and physically based predictive model-
ling. Advances in this modelling capacity have
underpinned the introduction of the flood risk
management paradigm, as has the broader para-
phernalia of geographic information systems (GIS)
and decision support systems. These powerful
tools need to be soundly based upon empirical
evidence. The path of analysis from empirical
evidence to risk-based recommendations should
be visible and open to scrutiny.
.
Risk based: Flood risk management is by defi-
nition risk based! The reason is that this provides a
rational basis for comparingmanagement options.
However, as we have seen already, evaluating the
likelihood and consequences of flooding now and
in the future is fraught with difficulties. We can in
future expect more scientific estimation of the
probabilities of relevant flooding processes, on a
range of different timescales. Methods for better
evaluation of the consequences of flooding and the
side-effects of flood risk management, on a range
of timescales, are urgently needed in practice and,
we expect, will be taken up enthusiastically as
soon as they are well tested by the research
community.
. Systems based: The nature and interactions of
multiple sources of flooding are beginning to be
understood. Surface water flooding in urban areas
may not be as devastating as a coastal dike breach,
but it occurs much more frequently and can be
disruptive to economic activity and society and
can cause loss of life. Thus all of these flooding
mechanisms need to be managed in an integrated
way. Arbitrary subdivision of the flooding system,
for example due to geographical boundaries or
administrative divisions, is to be avoided.
. Portfolio based: Integrated management in-
volves consideration of the widest possible set of
management actions that may have some impact
on flood risk. This includes measures to reduce
the probability of flooding and measures to reduce
flood impact (exposure and vulnerability) and de-
velopment of integrated strategies. Management
strategies are developed following consideration
of both effectiveness, in terms of risk reduction,
and cost. They will involve coordinating the ac-
tivities of more than one organization and multi-
ple stakeholders.
. Multi-level: Flood risk management cascades
from high-level policy decisions, based on outline
analysis, to detailed designs and projects or mea-
sures, which require more detailed analysis. High-
level policy and plans provide the framework
and common understanding within which more
detailed actions are implemented.
Robust: We have discussed above the impact
that uncertainty can have on flood risk manage-
ment decisions. Uncertainty analysis should
therefore not only be central to the process of
conducting flood risk analysis but should also
underpin the formulation of flood risk manage-
ment decisions and the evaluation of responses.
. Adaptive: Flood riskmanagement has to explic-
itly recognize change in flooding systems on a
range of timescales and due to a variety of process-
es. This will involve recasting many statistical
analyses and a renewed emphasis upon physically
based models (and necessary empirical observa-
tions) that can represent processes of change. It
implies a commitment to careful monitoring of
processes of change, including socioeconomic
change. More fundamentally, it will place more
emphasis upon the capacity of decision-makers to
deal with irreducible uncertainty and of designers
to innovate solutions that are flexible and adapt-
able in future.
. People based and democratic: Ahost of different
stakeholdershaveaninterestandrole intheprocess
of flood risk management. Successful risk reduc-
tion relies, to some extent, upon the engagement of
stakeholders in raising awareness of flood risk,
emergency management and recovery. The im-
pacts of floods include serious social and human
harm, and local peoplemaybe valuable providers of
local knowledge to help with implementing effec-
tive risk reductionmeasures. More broadly, people
at risk from flooding have a legitimate interest in
the decisions that are being taken on their behalf.
Thus effective flood risk management involves
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