Laserfiche WebLink
<br />rainfall and actual flooding will vary depending upon a variety of factors but <br /> <br />usually increases with the size of the upstream watershed. <br /> <br />About 20,000 communities in the United States are vulnerable to all categories <br /> <br />of floods (see Figure 3 and Table 1). River and flood forecast service is <br /> <br />provided to 3,100 of these. At the majority of locations with forecast <br />service, the rivers crest in 12 hours or more. Approximately 1,000 other <br /> <br />communities either have or are establishing local flood warning systems or are <br /> <br />receiving additional warning services from the National Weather Service <br /> <br />(NWS). This leaves thousands of communities without site-specific flood <br />warning services. <br /> <br />. <br /> <br />All counties receive generalized flash flood watches and warnings. A flash <br /> <br /> <br />flood is defined as one that occurs in a short time interval (minutes to <br /> <br /> <br />hours) following the causative event. A flash flood watch is issued by the <br />NWS if conditions indicate that flash floods are likely to occur in a <br />designated area. If flash flooding is imminent or reported, a flash flood <br />warning is issued on a county basis. Flash flood watches and warnings are <br /> <br />only a limited alerting and do not provide the specific forecast information <br /> <br />communities often need. <br /> <br />~ <br /> <br />. <br /> <br />What can a community do to reduce the threat of floods, thus saving lives and <br /> <br />reducing property damage? One cost-effective strategy is to establish a local <br /> <br />flood warning and response system. <br /> <br />4 <br />