The Pennsylvania Baseline Streamflow Estimator (BaSE)

Release Date:


The USGS, in cooperation with the Pennsylvania Department of Environmental Protection, Susquehanna River Basin Commission, and The Nature Conservancy, developed the Baseline Streamflow Estimator (BaSE) to estimate baseline streamflow at a daily time scale for ungaged streams in Pennsylvania using data collected during water years 1960– 2008. An in-depth evaluation of flow regimes to promote instream ecological health often requires streamflow information obtainable only from a time series hydrograph. Daily mean streamflow is estimated in BaSE using a methodology that equates streamflow as a percentile from a flow duration curve for a particular day at an ungaged location with streamflow as a percentile from the flow duration curve for the same day at a reference streamgage that is considered to be hydrologically similar to the ungaged location. As part of this work, new regression equations were developed to estimate 17 flow duration exceedances and new basin characteristics were added to StreamStats.

What is it?

BaSE is a Windows based application built using the .net 4.0 framework that can:

  • Estimate baseline streamflow (minimally altered by regulation, diversion, mining, or other anthropogenic activities) for ungaged streams in Pennsylvania
  • Generate a text file of daily mean streamflow for the ungaged site for the period 1960 to 2008
  • Create a report that includes streamflow data, exceedance probabilities, basin characteristics, and hydrographs for the ungaged site

What are the System Requirements?

Where can I get it?

BaSE and associated files are available for download through the USGS Publications Warehouse

Where can I get more detailed information about BaSE?

A full description of BaSE, including its limitations and accuracy, can be found in the below report. A User's Guide can be found in Appendix 5 of the report.


Stuckey, M.H., Koerkle, E.H., and Ulrich, J.E., 2012, Estimation of Baseline Daily Mean Streamflows for Ungaged Locations on Pennsylvania Streams, Water Years 1960-2008: U.S. Geological Survey Scientific Investigations Report 2012-5142, 61 p.

User Rights

This software and related material (data and documentation) are made available by the USGS to be used in the public interest and the advancement of science. You may, without any fee or cost, use, copy, modify, or distribute this software, and any derivative works thereof, and its supporting documentation, subject to the USGS Software User Rights Notice