Hydrology & Hydraulics

Hydrology studies involve modeling a geographic area known as a watershed. The watershed is the area from which rainfall will be collected and channeled to flow to the property or structure which is at risk for flooding. The watershed is comprised of subbasins, which are modeled in hydrology software with the land characteristics which affect the flow of water over the terrain in that subbasin. A worst-case design storm (usually the 100-year storm) is then modeled and the resulting water flow at certain points within the watershed is calculated.

Once the flow due to the 100-year or other storm is determined at certain points from the hydrology study, a detailed hydraulic study is performed to see how exactly that flow will affect a property or structure. The land terrain is modeled using closely-spaced survey points (usually from a LIDAR survey) and the water flow over that area is modeled in hydraulic software using engineering fluid mechanics equations.

This allows the engineer to determine, among other things, the extent of flooding, the depth of flooding, and the water velocity at any point within the surveyed area, and other detailed flood information. This information is critical to clients to establish the cause or potential risk of flood-related damage.