Simulation of natural flows in major river basins in Alabama

Scientific Investigations Report 2014-5021
Prepared in cooperation with the Alabama Department of Economic and Community Affairs—Office of Water Resources
By:  and 



The Office of Water Resources (OWR) in the Alabama Department of Economic and Community Affairs (ADECA) is charged with the assessment of the State’s water resources. This study developed a watershed model for the major river basins that are within Alabama or that cross Alabama’s borders, which serves as a planning tool for water-resource decisionmakers. The watershed model chosen to assess the natural amount of available water was the Precipitation-Runoff Modeling System (PRMS). Models were configured and calibrated for the following four river basins: Mobile, Gulf of Mexico, Middle Tennessee, and Chattahoochee. These models required calibrating unregulated U.S. Geological Survey (USGS) streamflow gaging stations to estimate natural flows, with emphases on low-flow calibration. The target calibration criteria required the errors be within the range of: (1) ±10 percent for total-streamflow volume, (2) ±10 percent for low-flow volume, (3) ±15 percent for high-flow volume, (4) ±30 percent for summer volume, and (5) above 0.5 for the correlation coefficient (R2). Seventy-one of the 90 calibration stations in the watershed models for the four major river basins within Alabama met the target calibration criteria. Variability in the model performance can be attributed to limitations in correctly representing certain hydrologic conditions that are characterized by some of the ecoregions in Alabama. Ecoregions consisting of predominantly clayey soils and (or) low topographic relief yield less successful calibration results, whereas ecoregions consisting of loamy and sandy soils and (or) high topographic relief yield more successful calibration results. Results indicate that the model does well in hilly regions with sandy soils because of rapid surface runoff and more direct interaction with subsurface flow.

Study Area

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Simulation of natural flows in major river basins in Alabama
Series title Scientific Investigations Report
Series number 2014-5021
DOI 10.3133/sir20145021
Year Published 2014
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Alabama Water Science Center
Description Report: vi, 32 p.; Appendix 1; Downloads Directory
Country United States
State Alabama
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
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