Decision support experiments and evaluations using seasonal to ...

The U.S. Climate Change Science Program Chapter 3
While few would
disagree that
uncertainties are
inevitable, there is
less agreement as
to how to improve
ways of describing
uncertainties
in forecasts
to provide
widespread
benefits.
96
many “champions”; however, questions remain
about whether resources for the initiative have
been adequate.
AHPS responds directly to the problem of timely
information availability by trying to provide
forecasting information sooner, particularly on
potential flooding; linking it directly to local
decision makers, providing the information in
a visual format; and, perhaps most of all, providing
a dedicated program within NOAA (and
the NWS) that has the capacity to work directly
with the user community and monitor ongoing,
evolving decision-support needs.
Vignette: AHPS—Advantages over
conventional forecasting
Applying the same hydrologic data used in
current methods, AHPS also employs advanced
hydrologic models with characteristics specific
to local watersheds and tributaries. These advanced,
localized hydrologic models increase
forecast accuracy by 20 percent over existing
models. Its outputs are more accurate, detailed,
and visually oriented, and are able to provide
decision makers and the public with information
on, among other variables: how high a river
will rise, when it will reach its peak, where
properties will be subject to flooding, and how
long a flood event will continue. It is estimated
that national implementation of AHPS will
save at least $200 million per year in reduced
flood losses and contribute an additional $400
million a year in economic benefits to water
resource users (Advanced Hydrologic Prediction
Service/ ).
Benefits and application
AHPS provides detailed products in an improved
format. Because it is visually oriented,
it provides information in a format that is easier
to understand and use by the general public as
well as planners and scientists. AHPS depicts
the magnitude and probability of hydrologic
events, and gives users an idea of worst case
scenario situations. Finally, AHPS provides
forecasts farther in advance of current methods,
allowing people additional time to protect
themselves, their families, and their property
from floods.
Following the Great Flood of 1993 in the
Midwest, the Des Moines River Basin in Iowa
was selected to be a location to test for the
first phase toward national implementation of
AHPS. Residents, via the Internet, can now
access interactive maps displaying flood forecast
points. Selecting any of the flood forecast
points on the map allows Internet users to obtain
river stage forecast information for the point of
interest. Available information includes: river
flood stages, flow and volume probabilities, site
maps, and damage tables projecting areas are
likely to be subject to flooding.
Status and assessment
A 2006 NRC report found AHPS to be an
ambitious climate forecast program that promises
to provide services and products that are
timely and necessary. However, it expressed
concerns about “human and fiscal resources”,
recommending that there is a need for trained
hydrologic scientists to conduct hydrologic
work in the NWS. Regarding fiscal resources,
“the budgetary history and current allocation
seem misaligned with the ambitious goals of
the program”. Thus, the program’s goals and
budget should be brought into closer alignment
(NRC, 2006).
3.3.2 Scientists Need to Communicate
Better and Decision-Makers Need a
Better Understanding of Uncertainty—
it is Embedded in Science
Discussions of uncertainty are at the center of
many debates about forecast information and
its usefulness. Uncertainties result from: the
relevance and reliability of data, the appropriateness
of theories used to structure analyses,
the completeness of the specification of the
problem, and in the “fit” between a forecast
and the social and political matters of fact on
the ground (NRC, 2005). While few would
disagree that uncertainties are inevitable, there
is less agreement as to how to improve ways of
describing uncertainties in forecasts to provide
widespread benefits (NRC, 2005). It is important
to recognize that expectations of certainty
are unrealistic in regards to climate variability.
Weather forecasts are only estimates; the risk
tolerance (Section 3.2.3) of the public is often
unrealistically low. As we have seen in multiple
cases, one mistaken forecast (e.g., the Yakima
basin case) can have an impact out of proportion