@ Bridge-Sites Studies

The U.S. Geological Survey (USGS) works closely with the Mississippi Department of Transportation (MDOT) to provide information to be used by the MDOT for design of highway-drainage structures. MDOT spends millions of dollars annually for highway construction.  Streamflow records, hydrologic analyses of basins, and hydraulic analyses of flooding potential at proposed highway crossings help the MDOT to make more informed decisions on the use of highway construction funding.  Flood-frequency and hydraulic characteristics at highway crossings are determined from historical flood-elevation data, cross-section data, and correlations with streamflow data from nearby gaging stations. Additional streamflow data are collected for ungaged sites when substantial flooding occurs in an area of interest to MDOT. This information not only provides the basis for the design of highways and drainage structures, but also is used by local agencies and the public for flood-plain management. The purpose of these data releases is to present selected basin characteristics, streamflows, and water-surface elevations for bridge sites studied in Mississippi. Estimates of flood-frequency peak streamflows with corresponding water-surface elevations for exceedance probabilities of 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent that correspond to recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively, are provided.