ETL 1110-2-540
30 Sep 96
a. Monitoring. The monitoring component of a flood-
using technology appropriate to the situation and the
threat recognition system can vary from a simple staff gage
institution's capabilities to perform the forecasting function is
that is observed and compared with a table or chart to an
important. Complex technologies employed in situations
elaborate system consisting of a network of automated
without local skills, resources, and long-term operational
precipitation and/or stream gages. This is dependent on the
commitment may quickly lead to system failure. Conversely,
size of the area, hydrometeorological characteristics, and the
it might not be appropriate to use solely monitoring where a
capabilities of the local community for operating and
forecast could provide time to reduce flood damage
maintaining the system. Data measurement and detection,
effectively. Appropriate technology considerations should be
generally accomplished by instruments in the field, are
reviewed extensively during system design. Reliability, and
important features of a monitoring system. The objective of
thus redundancy, is important. These considerations should
the measurement and detection task is to monitor developing
also be reviewed during the life of the system to account for
hydrometeorological conditions. This can include current
evolving local capabilities and experience gained during flood
watershed conditions and what might develop in the near
events. The value of a forecast is derived from the additional
term. Atmospheric parameters, measured rainfall, and
time made available for the response effort to reduce damage.
current stream conditions can be observed. Another essential
Figure 2-1 shows the flood warning - preparedness program
aspect of a monitoring system is data transmission, which is
continuum on a time scale relative to a flood event. It also
required to get the data to a central location for display and
shows how time saved by shortening the time needed to
assessment.
complete the flood-threat recognition system tasks contributes
directly to the time available to carry out response actions.
b. Forecasting.
(1) Flood-threat recognition systems may or may not
include flood forecasting. In any flood forecast system,
Figure 2-1. Flood warning - preparedness program time scale
2-2
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