Software Baseflow Filter Program
The baseflow filter estimates baseflow and groundwater recharge from streamflow records using the methodology outlined in Automated methods for estimating baseflow and groundwater recharge from streamflow records by J.G. Arnold and P.M Allen published in Journal of the Americam Water Resources Association vol 35(2) (April 1999): 411-424 and Automated base flow separation and recession analysis techniques by J.G. Arnold, P.M. Allen, R. Muttiah, and G. Bernhardt published in Ground Water vol 33(6): 1010-1018.
There are many baseflow filters available and the user is by no means required to use this particular baseflow filter with SWAT. However, we have found that model results are significantly improved if the ratio of surface runoff to baseflow is correct. We strongly recommend that some type of baseflow filter is used to provide an average annual ratio of baseflow to surface runoff for the calibration of model runs.
SWAT Bflow is a baseflow filter program that offers a Web Interface to determine runoff/baseflow fraction in streamflow and the baseflow alpha factor required in SWAT .gw files. Its search algorithm is adopted from Arnold and Allen (1999). SWAT Bflow offers a Google Map interface with one-click query to access USGS gages. Users can upload local flow data as well for analysis. Requirement: any web browser and internet connection.