FLOOD FREQUENCY BASED DESIGN - Technical Paper No. 7

The Red River Basin Flood Damage Reduction Work Group has proposed goals for flood damage reduction in the Red River Basin. One of the goals is to provide protection to intensively farmed agricultural land from a 10-year summer storm. Toe Work Group asked the Technical and Scientific Advisory Group to write this paper to explain what is meant by a 10-ye􀄚 summer storm in laymen's terms. In its simplest form, this goal would mean a property has a 10% chance in any one ye!lr, during a summer storm, of being flooded by water from another property. To understand what this means takes further explanation. In general, all water resources projects are comprised of physical components such as channels, pipes and culverts, detention dams, erosion control structures and stilling basins, and drop structures or chutes. The engineering hydraulic design of these structures requires some knowledge as to the amount of water that 􀇌ill pass through the facilities. The amount of water is usually characterized in terms of volume ( cubic feet, acre-feet, etc.), or volumetric rate of flow (cubic feet per second, acre-feet per month, etc.). The determination of flow rates for the design of hydraulic structures is commonly termed hydrologic engineering.