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1
~ Introduction
FLOODS: A SIGNIFICANT NATIONAL HAZARD
Floods are the most devastating of all weather-related
hazards in the United States (see Figure 1-1~. Floods often
produce tragic and disastrous extremes in losses of both life
and property. Over the past 30 years floods have claimed an
average of 139 lives per year compared with 87 lives lost per
year by lightning, 82 by tornadoes, and 27 by hurricanes
(NOAA, 1994a). (In recent years, the average annual
flood-related death toll has risen to nearly 200.) During the
same 30-year period, property damage caused by floods av-
eraged approximately $1 billion per year. This amount is
nearly twice that associated with tornadoes and hurricanes,
and recently it has averaged nearly $2 billion per year. The
continuing industrialization and population growth of river
valleys are increasing the economic cost and death toll of
flood-related disasters. Flash floods are an especially dan-
gerous threat. A single flash flood in 1976 on the Big
Thompson River in Colorado claimed 139 lives. After the
Great Midwest Flood of 1993, property damage was esti-
mated at $15 billion. Since the 1993 Midwest Flood, seven
other weather-related disasters in the United States have each
caused over $1 billion in damages; five of these seven disas-
ters were floods. Overall, 75 percent of all presidential disas-
ter declarations are for flood damage, and more than 85 per-
cent of disaster declarations result from weather of all types
(Chapman, 1992; NOAA, 1995a).
At the opposite extreme from floods, prolonged droughts
also bring major economic and social disruption by losses in
agriculture and food production. Furthermore, low-flow con-
ditions in streams and rivers associated with droughts have
adverse ecological effects on fish populations and riparian
zone (river-bank) habitats. Low-flow conditions also impact
navigation and industrial activities that are dependent on
water in the river network. For example, river commerce in
the upper Midwest literally bottomed out after the devastat-
ing drought of 1988, which had an economic toll exceeding
$40 billion. Drought conditions in 1996 have caused crop
losses estimated in the hundreds of millions of dollars in
central and southwestern regions of the United States.
Many of the nation's watersheds are now managed and
controlled through flood control reservoirs, storage reser-
voirs, hydroelectric production, water quality and erosion
control measures, and land management. The operation and
optimum management of these systems require forecasts on
time scales that range from hours to seasons. The economic
benefit of providing accurate hydrologic projections for these
activities is estimated by the National Weather Service
(NWS) to approach $1 billion or more annually (NWS,
1996a).
The NWS is charged by Congress to provide flood fore-
casts and warnings to the public to protect life and property.
The NWS mission in hydrology services also extends to the
provision of basic hydrologic forecast information to pro-
mote the nation's economic and environmental well-being
(Starlings and Wenzel, 1995~. Many types of hydrology
products and services support a wide range of user commu-
nities. User communities include the general public, the news
media, emergency managers at all levels of government,
public works and safety agencies, and water resource and
floodplain managers throughout the United States.
MODERNIZATION OF TH E NATIONAL
WEATHER SERVICE
The NWS is currently undergoing a comprehensive mod-
ernization and associated restructuring program that is in-
tended to improve substantially weather and hydrologic
warning and forecast products and services) in the United
States. The modernization of the NWS, under way for over a
decade, entails the deployment of proven observational,
information processing, and communications technologies
and the establishment of an associated operational structure.
The goal of the modernization program is to ensure that the
tin the context of this report, any technical output from the NWS,
whether from one office to another or to external users, is a "product." The
term "guidance," also used often in this report, describes products used
internally or between offices.
6
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INTRODUCTION
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FIGURE 1-1 Notable floods and flash floods from 1987 to 1991. Source: NWS (1992~.
major scientific and technological advances that have been
made in the ability to observe and understand the atmosphere
are applied to the practical problems of providing weather
and hydrologic services to the nation.
The new observing systems include the Weather Surveil-
lance Radar 1988 Doppler (WSR-88D) Next Generation
Weather Radar (NEXRAD), the Automated Surface Observ-
ing System (ASOS), and the Next Generation Geostationary
Operational Environmental Satellites (GOES-Next). An
Advanced Weather Interactive Processing System (AWIPS)
will provide critical information processing, interactive fore-
cast environments at each field office, and a vital, high-speed
communications link among all the offices.
The associated restructuring of the NWS is driven by
these new technologies. The premodernization field office
structure included 52 Weather Service Forecast Offices
(WSFOs); approximately 200 smaller offices (mostly
Weather Service Offices [WSOs], which take manual
weather observations and issue local-area forecasts based on
guidance from the WSFOs as well as warnings based on a
local weather radar); and 13 River Forecast Centers (RFCs).
The modernized structure of the NWS includes 13 RFCs and
Deaths
Damage >500,000
119 Weather Forecast Offices (WFOs)2 at locations deter-
mined primarily by the coverage of NEXRAD systems in-
stalled nearby.3
In January 1991 the NWS Office of Hydrology first pub-
lished its Hydrometeorological Service Operations for the
1990s (NWS, 1991, 1996a). This plan, most recently up-
datedin March 1996, describes the activities at RFCs, WFOs,
and regional and national headquarters offices for the vari-
ous transition phases that lead up to and extend into the era
of the modernized and restructured NWS. The plan includes
the status of critical path decisions and policies, staffing
2The original strategic plan (DOC, 1989) for restructuring of the NWS
called for 115 WFOs. Staffing analyses by the NWS led to the decision to
assign a total of 78 service hydrologists to the WFOs. In the intervening
years since the strategic plan was published, various activities, the most
recent being a study of NEXRAD coverage (NRC, 1995), have led to ad-
justed totals of 119 WFOs and 80 service hydrologists. Although final bud-
get approval for this planning baseline is not complete, the remainder of this
report cites 119 WFOs and 80 service hydrologists.
3 The spatial responsibilities of RFCs are determined by physiographic
boundaries (watershed basins) whereas WFO boundaries are geopolitical
(counties).
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8
ASSESSMENT OF HYDROLOGIC AND HYDROMETEOROLOGICAL OPERATIONS AND SERVICES
analysis, a master training plan, and a hydrologic systems
support plan. The l990s plan has received wide distribution
within the NWS and reflects the policy, technical, and pro-
grammatic decisions coordinated by NWS headquarters, re-
gional offices, and field office managers.
SCOPE AND ORGANIZATION OF
THE REPORT
With the implementation of a new network of advanced
weather radars nationwide as part of the modernization pro-
gram, and with the concomitant availability of advanced
communication and computation technologies, the NWS will
have an unprecedented opportunity to deliver highly im-
proved hydrology forecast and warning products and ser-
vices to the public. This report addresses technical and man-
agement issues that affect the realization of that opportunity.
The modernization of hydrologic services in the NWS is
considered in its entirety tools and techniques, observation
systems, operations, and management are all discussed. Each
component contributes to the issuance of hydrologic forecasts
and warnings at some stage in the life cycle of forecast prepa-
ration. Therefore all of these topics must be critically evalu-
ated as part of an overall assessment of the modernized NWS
and its readiness to deliver advanced and improved hydro-
logic forecast products and services to the public and other
user communities.
In Chapter 2 the interactions between hydrology and me-
teorology in the NWS, both before and after the current mod-
ernization, are described. A particular focus is placed on the
roles and responsibilities of the RFCs and WFOs in the mod-
ernized NWS. Chapter 3 presents a discussion and evalua-
tion of the various tools and techniques, observation inputs,
operations, and products and services that comprise the mod-
ernization of hydrologic services. In Chapter 4 management
and operational support issues such as leadership, research
and development, operational test and evaluation, staffing,
and training are discussed. All of the committee's recom-
mendations appear in Chapters 3 and 4. Finally, Chapter 5
presents a brief synoptic assessment of the direction and out-
look for the modernization of hydrologic products and ser-
vices in the NWS.
Representative terms from entire chapter:
field office
