Environmental Engineering Reference
In-Depth Information
Better evidence can be characterized as:
. An improved understanding of the performance
of the individual assets- the importance of good-
quality data cannot be overestimated, including
direct access to basic parameters such as the lo-
cation, condition and the standard of protection an
asset affords as well as more accurate and usable
information on probability of failure, dominant
failure modes and critical uncertainties.
. A better understanding of asset performance
and the individual contributions of assets to the
residual risk - including direct access to informa-
tion on how an individual asset contributes to the
overall performance of the system and its contri-
bution to residual risk (Fig. 15.2).
. Affordability: Budgets are limited and it is com-
mon to have insufficient resources (time and
money) to undertake all 'desirable' works. For
example, in the USA it has been estimated that
$2.2 trillion would be needed to raise all linear
defences (levees) to the desired standard and con-
dition (Stockton 2009).
Better Asset Management: Rising to the
Challenge
Around theworld innovative tools and techniques
are being developed to better support asset man-
agers in overcoming the challenges they face
(Havinga and Kok 2003; USACE 2008; Environ-
ment Agency 2010). This is in recognition that
structural responses (including the ongoing man-
agement of existing assets) will continue to play a
major role in flood risk management into the
future (e.g. 'A Safe Public and Reduced Economic
Losses by means of Reliable Levees - part of an
Integrated Solution to Flooding', taken from the
USACE, National Committee on Levee Safety,
October 2008).
Common threads emerge from these activities,
including a drive for better evidence on individual
assets and better decision-making.
Better decision-making
All asset managers seek to make good investment
decisions - decisions that minimize whole-life
costs and maximize environmental gain whilst
ensuring communities are appropriately protected
from flooding now and in the future. Increasingly,
consistent analysis techniques (Sayers and
Meadowcroft 2005; Gouldby et al. 2008, 2009) and
decision support tools (Surendran et al. 2008;
McGahey and Sayers 2008; Environment Agen-
cy 2010) are available to support decision-making.
These tools and techniques provide a step change
in the 'richness' of the evidence provided to deci-
sion-makers at all levels (across national, flood
system and individual asset levels). In particular,
they provide:
. An improved understanding of the role that
an individual asset plays within a larger asset
system - by highlighting those assets, within a
system of assets, that contribute most to residual
risk. Further disaggregation of the risk, to high-
light the separate contributions from breach and
overtopping, enables the asset manger to distin-
guish the relative importance of raising crest
heights or improving asset strength.
. A better understanding of the impact of uncer-
tainty within the estimated risk - by highlighting
those assets that contribute most to the uncer-
tainty in the estimates of risk the asset manager is
Better evidence on individual assets
In England and Wales, the Environment Agency
has stated that it will have succeeded in its asset
management role when it knows exactly 'what
assets we have; where they are; what standard of
protection they provide; how they were con-
structed; their current engineering integrity; and,
how they work together to provide a flood defence
system' (Tim Kersley - Head of Asset Manage-
ment, Environment Agency, 2008). Similar, seem-
ingly basic requirements, can be seen to exist
around the world and across sectoral disciplines
(within rail, road, etc.) and are a central thrust of
the USACE National Levee Safety Program
(USACE 2008).
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