The most critical element in flood damage reduction is emergency preparedness and response. The awareness of the community at risk of flooding should be raised and maintained, with a clear understanding of their role in responding to emergencies appropriately. This is critical in organizing coordinated evacuation from the affected area and maintaining healthy and hygienic conditions in the flooded areas. Information on evacuation routes as well as identified emergency shelters and other actions should be available, to all concerned, well in advance. Flood-prone populations should be dissuaded from storing harmful chemicals during the flood season, made aware of likely pollutants in floodwaters and advised of the ways to avoid their adverse impacts. Actions undertaken during floods to prevent damage, such as diverting floods from sensitive areas, are generally known as flood fighting or flood combat. When flood control and protection works and other types of measures either have failed or have been insufficient to fully overcome the impact of flooding, these emergency measures become effective in mitigating flood impacts on society and environment.

After a flood, the cleaning operations are undertaken at an emergency level and little attention may be paid to the dumping of rubbish and debris. If not planned in advance, it may end up in drainage channels, ponds, wetlands or rivers, impacting the natural ecosystems. Recovery of drinking water supply, tube wells, sewerage systems and health infrastructure should be the priority. The spread of chemicals during floods can have catastrophic consequences on terrestrial ecosystems and requires earliest cleaning up. These cleaning operations require special attention in the post recovery phase to avoid long-term ill effects. (WMO 2006a)