User’s Guide for the Baseline Streamflow Estimator (BaSE)

Scientific Investigations Report 2012–5142

Appendix 5 to accompany

U.S. Department of the Interior

U.S. Geological Survey

User’s Guide for the Baseline Streamflow 

Estimator (BaSE)

By Marla Stuckey, Edward Koerkle, James Ulrich

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5142

Appendix 5 to accompany
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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Suggested citation:

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.

Although this program has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is 

made by the USGS or the U.S. Government as to the accuracy and functioning of the program and related program 

material nor shall the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS 

in connection therewith.
iii

Contents

Introduction...................................................................................................................................................57

Computer Requirements and Installation Instructions..........................................................................57

Data Input Requirements............................................................................................................................57

Running the BaSE Tool................................................................................................................................58

References Cited..........................................................................................................................................60

Figures

5–1. Screen capture of the opening screen of BaSE....................................................................58

5–2. Screen capture of StreamStats toolbar..................................................................................58

5–3. Screen capture showing an example entry of basin characteristics into BaSE.............59

5–4. Screen capture of the summary report generated from BaSE...........................................60

5–5. Screen capture showing manually selecting a reference streamgage for use 

with BaSE.....................................................................................................................................61

Tables

5–1. Basin characteristics with naming conventions used in StreamStats and regression 

equations for predicting flow-duration exceedance probabilities for Pennsylvania 

streams.........................................................................................................................................59
iv
User’s Guide for the Baseline Streamflow Estimator (BaSE)

By Marla Stuckey, Edward Koerkle, and James Ulrich

Introduction

The Baseline Streamflow Estimator (BaSE) is a tool to 

simulate minimally altered streamflow at a daily time step for 

an ungaged location during water years 1960–2008. BaSE was 

developed by the U.S. Geological Survey (USGS), in cooperation with the Pennsylvania Department of Environmental 

Protection, Susquehanna River Basin Commission, and The 

Nature Conservancy. The tool uses a modified QPPQ approach 

(Fennessey, 1994; Archfield and others, 2010), which relates 

probability exceedances at a gaged site to an ungaged location. An appropriate streamgage is selected in BaSE using 

streamflow correlation or the user can manually select a different streamgage. The streamgage selected, termed “reference” streamgage, should be representative of the ungaged 

basin with similar hydrologic and basin characteristics and 

have minimally altered streamflow by human activities. A 

report file is generated documenting the reference streamgage 

and ungaged location information, any warnings, and basic 

statistics including the median flow. The estimated daily flows 

for the ungaged location can be easily exported to a .csv file 

that can be used as input into a statistical software package to 

determine further streamflow statistics.

Computer Requirements and 

Installation Instructions

Microsoft Excel® 97–2010 (or later) and .net framework 

4.0 are required on the machine running BaSE. The tool and 

associated report can be downloaded from the USGS Publications Warehouse. To download BaSE, go to http://pubs.usgs.

gov/sir/2012/5142/, click on the link for the Baseline Streamflow Estimator, and download BaSE_v.1.0.zip. Extract the 

files from the zip file and save them to your computer. Install 

BaSE by double clicking on the file “setup.exe” (administrative privileges are not typically required to install/uninstall 

this application). During this step, the program checks for 

prerequisites and will notify you of any problems or missing 

software. After successful installation, the program will be 

found in your start menu in a folder named “USGS PA WSC” 

and a shortcut will also be created on your desktop.

Data Input Requirements

BaSE requires basin characteristics for the ungaged 

location to be entered on the opening screen (fig. 5–1). The 

tool can obtain these values from a downloaded geodatabase 

file from StreamStats (http://water.usgs.gov/osw/streamstats/

pennsylvania.html) or the user can manually enter the basin 

characteristics. The following basin characteristics are 

required entries: longitude of the outlet of the basin, drainage area, mean annual precipitation, mean maximum daily 

temperature, soil depth to bedrock, drainage runoff number, 

percent of basin underlain by carbonate bedrock, percent of 

impervious surface area in basin, x-location at the center of 

the basin, y-location at the center of the basin, x-location at 

the outlet of the basin, and y-location at the outlet of the basin. 

More information about these basin characteristics, including data sources, can be found in the body of this report. It is 

important to use the same data source as was used to develop 

the regression equations for determination of the basin characteristics to maintain consistent accuracy in the regression 

estimates. To clear entered basin characteristics, click on the 

button “Clear Form”.

To use StreamStats to obtain basin characteristics for 

the ungaged location, go to StreamStats for Pennsylvania at 

http://water.usgs.gov/osw/streamstats/pennsylvania.html and 

click on the Interactive Map link in the middle of the screen 

(fig. 5–2). Detailed instructions for using StreamStats can be 

found at the StreamStats website. Zoom to the area of interest by selecting an area using the magnify button, or enter a 

latitude and longitude. A scale of 1:24,000 or larger must be 

used to delineate a basin; use the zoom button to set the scale. 

Delineate the basin using the button with a black dot and plus 

sign (fig. 5–2, yellow arrow), and check the basin to make sure 

it is correctly delineated. After the basin has been correctly 

delineated, select the button with a table and question mark 

(fig. 5–2, green arrow) to compute basin characteristics. You 

can select all basin characteristics or only those needed. To 

download the data, click on the button with the arrow pointing down to a disk drive (fig. 5–2, red arrow) using the .mdb 

option (note–default is shapefile so you need to click on the 

circle for .mdb). This will save a zip file to your computer; the 

file will be named with a series of numbers that includes the 

date and time. The file must be unzipped before using BaSE. 
58 Estimation of Baseline Daily Mean Streamflows for Ungaged Locations on Pennsylvania Streams, WY 1960–2008

Basin characteristic notations in the geodatabase file downloaded from StreamStats may be different than those used in 

the regression equations. The naming conventions used in 

StreamStats for the basin characteristics needed to run BaSE 

are listed in table 5–1.

Running the BaSE Tool

The opening screen of BaSE includes cells to enter basin 

characteristics. If a file from StreamStats is to be used to 

enter basin characteristics, select the button at the top, Import 

StreamStats database (fig. 5–3, black circle), and navigate to 

the downloaded file. The user can enter the basin characteristics manually, if they are known. The range of values for each 

basin characteristic used to develop the regression equations is 

shown. A warning message will appear if the basin characteristic entered is outside this range (fig. 5–3, red circle), indicating 

the resulting flow-duration estimates determined from regression equations may not be valid.

After basin characteristics have been entered for the 

ungaged location, click on Compute Baseline Flows button 

(fig. 5–3, arrow) to select the reference streamgage and compute baseline daily flows. The user will have to agree to the 

disclaimer that appears before continuing. The computation of 

daily flows will take a few minutes, depending on the computing capacity of your computer. A status bar indicates progress. 

When computations are completed, a box will open asking 

you to save the resulting Microsoft Excel® file. This file is the 

output from the tool. After saving the file, close the file before 

attempting to run BaSE for another location. BaSE may not 

function properly when this file is open.

Figure 5–1. The opening 

screen of BaSE.

Figure 5–2. StreamStats toolbar. (Yellow arrow shows Basin delineation from a point; green arrow shows Obtain Basin Characteristics; 

red arrow shows Download option)
Appendix 5. User’s Guide for the Baseline Streamflow Estimator (BaSE) 59

Table 5–1. Basin characteristics with naming conventions used in StreamStats 

and regression equations for predicting flow-duration exceedance probabilities 

for Pennsylvania streams.

[—, not used in regression equations]

Basin characteristic

Notation used 

in regression 

equations

Naming 

convention used 

in StreamStats

Longitude at the outlet of the basin Long LONG_OUT

Drainage area DA DRNAREA

Mean annual precipitation Ppt PRECIP

Mean maximum daily temperature MaxT MAXTEMP

Soil depth to bedrock Thk ROCKDEP

Drainage runoff number Drn DRN 

Percent of basin underlain by carbonate bedrock Carb CARBON

Percent of impervious surface area Imp IMPNLCD01

x-location at the center of the basin — CENTROIDX

y-location at the center of the basin — CENTROIDY

x-location at the outlet of the basin — OUTLETX

y-location at the outlet of the basin — OUTLETY

Figure 5–3. An example entry of basin characteristics into BaSE. (Black oval shows button to import data from StreamStats; 

red oval shows basin characteristic warning; black arrow points to the button to compute baseline daily mean streamflow)
60 Estimation of Baseline Daily Mean Streamflows for Ungaged Locations on Pennsylvania Streams, WY 1960–2008

The output Microsoft Excel® file contains worksheets 

with reference gage information, daily flows for the reference site and ungaged location, probability exceedances 

for the reference site and ungaged location, and a summary 

report with hydrographs and flow duration curves (fig. 5–4). 

Reference streamgages located outside a 75-mile radius 

from the ungaged location will result in a warning message. 

Correlations outside this radius may not be valid because 

of the method used to develop the correlation maps. The 

worksheet named ReferenceGageSelection lists information about the reference streamgage selected and four other 

reference streamgages with the highest correlations to the 

ungaged location. The distances between the ungaged location and reference streamgages are listed in the table and 

can be used to evaluate the appropriateness of the selected 

streamgage. To save the estimated daily flows and dates for 

the ungaged location as a comma delimited file, click on the 

Export Daily Values button on the report worksheet (fig. 5–4, 

black circle). Macros need to be enabled to use this feature. 

To enable macros, click on enable content from the message 

bar or under File; Info; Security Warning; Enable Content; 

select Enable All Content. The exported .csv file can then be 

used as input into a number of statistical software packages to 

determine low-flow, flow-duration exceedance, base-flow, or 

mean-flow statistics.

The reference streamgage can be chosen by the user, 

overriding the spatial map correlation process. After the basin 

characteristics have been entered for the ungaged location in 

BaSE, go to the tab Reference Gage Selection (fig. 5–5, black 

circle), and choose the reference streamgage you want to use. 

Click on Compute Baseline Streamflows to proceed with 

calculations. Review the results and follow the data export 

procedures to save the data into a file for further use. 

References Cited

Archfield, S.A., Vogel, R.M., Steeves, P.A., Brandt, S.L., 

Weiskel, P.K., and Garabedian, S.P., 2010, The Massachusetts Sustainable-Yield Estimator: A decision-support tool 

to assess water availability at ungaged stream locations in 

Massachusetts: U.S. Geological Survey Scientific Investigations Report 2009–5227, 41 p., plus CD-ROM.

Fennessey, N.M., 1994, A hydro-climatological model of daily 

streamflow for the northeast United States: Medford, Mass., 

Tufts University, Ph.D. dissertation [variously paged].

Figure 5–4. Summary 

report generated from 

BaSE. (Black oval shows 

the button to export 

daily streamflow for the 

ungaged location as a 

.csv file.)
Appendix 5. User’s Guide for the Baseline Streamflow Estimator (BaSE) 61

Figure 5–5. Manually selecting a reference streamgage for use with BaSE.

Prepared by the West Trenton Publishing Service Center

For additional information write to:

Director, Pennsylvania Water Science Center

U.S. Geological Survey

215 Limekiln Road

New Cumberland, PA 17070-2424

http://pa.water.usgs.gov/
Stuckey and others—User’s Guide for the Baseline Streamflow Estimator (BaSE)—Appendix 5 to accompany Scientific Investigations Report 2012–5142