Introduction to Floodplain Modeling and Management

Floodplain modeling is a comparatively recent engineering discipline, with the current procedures evolving out of engineering and scientific experiments that were conducted in the eighteenth and nineteenth centuries. Only since the end of World War II, however, has significant engineering effort been devoted to the subject of floodplain modeling. Yet, without floodplain modeling, the design of much of the world's infrastructure would be haphazard at best and dangerous at worst. Engineers use floodplain modeling for basic urban planning to consider the effect of potential flood levels on the community, even if no flood protection is planned. Modeling can estimate the water surface elevations during selected flood events, thereby preventing unwise land use in floodprone areas. The design of bridge and culvert openings for roadway crossings of streams is predicated on proper floodplain hydraulic analysis as well as flood reduction measures, such as dams, levees, and channel modifications. The principles of floodplain modeling can also be applied on a small scale; for example, to design drainage ditches and storm sewers.

This chapter begins with an introduction to floodplain studies from a historical perspective, proceeding through to modern-day floodplain modeling using HEC-RAS. The general modeling techniques are then presented, highlighting the key benefits of each. The chapter concludes with a discussion of the major application areas of floodplain models.