11.2 hydrOlOGic aspects OF FlOOd warninG prOGraMs A major emphasis of water resources monitoring and forecasting systems is for flood warning and preparedness. Other tasks may apply to longer time frames, such as drought monitoring. Flood warning/preparedness programs (FWPPs) have been a priority for several decades, since recogni- tion that technologies for monitoring and forecasting of floods can support public responses for avoidance and mitigation (USACE 1996). FWPPs are a part of comprehensive flood-damage reduc- tion programs along with other structural and nonstructural measures. These programs reduce the risk to life and, to some extent, reduce the damage potential during flood episodes. FWPPs do not prevent flood disasters, but they do enable institutional and public emergency response actions to be conducted more effectively. Many institutional arrangements required for implementing flood warning/preparedness programs are similar to those for other disasters. Hydrologic analyses are important in evaluating the feasibility of implementing FWPPs and to ensure their validity of operation on a real-time basis during flood events. Information presented in Chapter 9 (GIS for Floodplain Management) describes how base conditions are determined on the nature of the flood hazard for a range of events (magnitude, frequency, inundation boundaries, velocities, depths, and warning times). These analyses may result in impacts to threatened proper- ties and vital services. Enhanced condition analyses include arrangements, equipment, hardware/ software, and actions that yield better responses. The analyses may include enhanced and more- reliable warnings, better warning dissemination, and response actions that can reduce the number of casualties or deaths and the threat of property damage.