Storm Water Flood Studies

Challenges

Floods are one of the most common hazards in the United States. Flood effects can be local, impacting a neighborhood or community, or very large, affecting entire river basins and multiple states.

Approach

Jones & Henry has performed various studies related to flooding following FEMA criteria. FEMA routinely updates flood insurance studies (FIS) incorporating new data (i.e. recorded flood stages, rainfall data, etc). Jones & Henry has actively been involved in these sorts of updates, which have consequently led to formal modifications to FEMA Flood Insurance Rate Maps (FIRMs) via the Map Revision process.

Flood studies are an important first step in determining the root cause of repeated flooding in certain areas or zones. These studies incorporate numerous tools including floodway surveys, peak flow monitoring, historical flood elevations, rainfall-runoff characteristics and real-time monitoring. With this data, accurate representations can be developed for the study areas along with corresponding recommendations for improvements.

We use sophisticated computer programs for hydraulic analysis, which contain comprehensive water quantity and quality computer simulation models. Single-event and continuous simulations are performed for most components of rainfall and runoff for a given watershed. The software also includes complete dynamic flow routing for hydraulic simulations such as backwater, looped drainage networks, surcharging, hydraulic and energy grade line analysis, and a multitude of other hydraulic conditions.

These computer programs can provide output that is available for graphical display within Geographic Information Systems (GIS). Information from simulations that can be displayed includes, but is not limited to:

  • Maximum water surface elevations at manholes
  • Profiles of maximum water surface elevations along selected stretches of sewers
  • Volume and duration of surface flooding
  • Duration and location of surcharged conduits
  • Total volumes through conduits
  • Maximum flows in conduits

Services

  • Formal submittal to FEMA to gain Map Revisions to FIRM’s
  • Determination of 1-yr, 10-yr, 25-yr, 100-yr flood impact areas based on computer modeling (generate LOMR if requested)
  • Rainfall vs. runoff characteristics for catchments
  • Soils analyses based on historic and lab testing criteria
Jones & Henry
Engineers, Ltd.