Louisiana StreamStats

Louisiana StreamStats incorporates regression equations for estimating instantaneous annual peak flows corresponding to annual exceedance probabilities (AEPs) of 50, 20, 10, 4, 2, 1, 0.5 and 0.2 percent (recurrence intervals of 2, 5, 10, 25, 50, 100, 200 and 500 years, respectively) in both the Mississippi Alluvial Plain (Anderson, 2021) and the rest of the state (Ensminger and others, 2024).  Basin characteristics available in StreamStats include drainage area, length of the longest flow path, 10-85 slope, basin shape factor, and mean annual precipitation for the period 1971-2000.  Estimates of bankfull width, depth, and channel cross-sectional area (Bieger and others, 2015) and the maximum probable flood (Crippen and Bue, 1977) are also provided. 

The reports listed below document the regression equations, the methods used to develop them and the basin characteristics used in the equations, the errors associated with the estimates obtained from the equations, and the methods used to develop the bankfull and maximum probably flood statistics.  Users should familiarize themselves with these reports before using StreamStats to obtain estimates of flows for ungaged locations on streams in Louisiana.

• Ensminger, P.A., Wagner, D.M., and Whaling, A.R., 2024, Magnitude and frequency of floods in the Coastal Plain region of Louisiana, 2016:  U.S. Geological Survey Scientific Investigations report 2024-5031, 18 p., https://doi.org/10.3133/sir20245031
• Anderson, B.T., 2021, Magnitude and frequency of floods in the alluvial plain of the lower Mississippi River, 2017:  U.S. Geological Survey Scientific Investigations report 2021-5046, 15 p., https://doi.org/10.3133/sir20215046
• Bieger, Katrin; Rathjens, Hendrik; Allen, Peter M.; and Arnold, Jeffrey G.,2015, Development and Evaluation of Bankfull Hydraulic Geometry Relationships for the Physiographic Regions of the United States, Publications from USDA-ARS / UNL Faculty, 17p.
• Crippen, J.R. and Bue, Conrad D.1977, Maximum Floodflows in the Conterminous United States, Geological Survey Water-Supply Paper 1887, 52p.

Click on this link to obtain general information on the Louisiana application, as well as specific sources and computation methods for basin characteristics.