Decision support experiments and evaluations using seasonal to ...

The U.S. Climate Change Science Program
Water management
in coastal urban
areas faces unique
challenges due
to vulnerabilities
of much of the
existing water supply
and treatment
infrastructure
to storm surges,
coastal erosion,
coastal subsidence,
and tsunamis.
104
(Obeysekera et al., 2007). The WSE schedule
uses states of ENSO and the Atlantic Multidecadal
Oscillation (AMO) (Enfield et al., 2001)
to estimate the Lake Okeechobee net inflow
outlook for the next six to 12 months. A decision
tree with a climate outlook is a unique component
of the WSE schedule and is considered a
major advance over traditional hydrologic rule
curves typically used to operate large reservoirs
(Obeysekera et al., 2007). Evaluation of the
application of the WSE schedule revealed that
considerable uncertainty in regional hydrology
remains and is attributable to some combination
of natural climatic variation, long-term global
climate change, changes in South Florida precipitation
patterns associated with drainage and
development, and rainfall-runoff relationships
altered by infrastructure changes (Obeysekera
et al., 2007).
Lessons Learned
From its experience with climate information
and research, SFWMD has learned that to
improve its modeling capabilities and contributions
to basin management, it must improve
its ability to: differentiate trends and discontinuities
in basin flows associated with climate
variation from those caused by water management;
gauge the skill gained in using climate
information to predict basin hydroclimatology;
improve management; account for management
uncertainties caused by climate variation and
change; and evaluate how climate change projections
may affect facility planning and operation
of the SFWMD (Bras, 2006; Obeysekera
et al., 2007).
The district has also learned that, given the
decades needed to restore the South Florida
ecosystem, adaptive management
is an effective way to
incorporate SI climate variation
into its modeling and
operations decision-making
processes, especially since
longer term climate change
is likely to exacerbate operational
challenges. As previously
stated, this experiment
is also unique in being the
only one that has been identified
in which decadal climate
status (e.g., state of the AMO) is being used in
a decision-support context.
Experiment 2:
Long-Term Municipal Water Management
Planning—New York City
The Experiment
Projections of long-term climate change, while
characterized by uncertainty, generally agree
that coastal urban areas will, over time, be
increasingly threatened by a unique set of hazards.
These include sea-level rise, increased
storm surges, and erosion. Two important
questions facing decision makers are: (1) How
will long-term climate change increase these
threats, which are already of concern to urban
planners? and (2) Can information on the likely
changes in recurrence intervals of extreme
events (e.g., tropical storms) be used in long
term municipal water management planning
and decision making?
Background and Context
Water management in coastal urban areas faces
unique challenges due to vulnerabilities of
much of the existing water supply and treatment
infrastructure to storm surges, coastal erosion,
coastal subsidence, and tsunamis (Jacobs et
al., 2007; OFCM, 2004). Not only are there
risks due to extreme events under current and
evolving climate conditions, but many urban
areas rely on aging infrastructure that was
built in the late nineteenth and early twentieth
centuries. These vulnerabilities will only be
amplified by the addition of global warminginduced
sea-level rise due to thermal expansion
of ocean water and the melting of glaciers,
mountain ice caps and ice sheets (IPCC, 2007).
Chapter 4