Thus, extensive urbanization also decreases the lag time and increases the peak discharge even further. Urbanization can therefore lead to a higher incidence of flash floods. An engineering approach, to control flooding, and a regulatory approach designed to decrease vulnerability to flooding. As discussed above, channelization. In other words by enlarging the cross-sectional area, higher discharge can be held within the channel.
Channelization also increases water velocity, and thus reduces drainage time.
Dams - Dams can be used to hold water back so that discharge downstream can be regulated at a desired rate. Human constructed dams have spillways that can be opened to reduce the level of water in the reservoir behind the dam. Thus, the water level can be lowered prior to a heavy rain, and more water can be trapped in the reservoir and released later at a controlled discharge. Retention ponds - Retention ponds serve a similar purpose to dams. Water can be trapped in a retention pond and then released at a controlled discharge to prevent flooding downstream.