American River Watershed Institute

Sierra Climate Change Watershed Yield Calculator

The Calculator is a practical tool for evaluating the influence of climatic change on watershed yield for the west slope Sierra Nevada.


  • In order to use the Calculator, you will need Microsoft's .NET Framework software. Updated versions of Microsoft® Windows® XP will already have it as part of the operating system.

  • The Calculator itself consists of a couple of small files. Some examples are included with the Calculator.

  • Instructions on how to load the software and how to use the Calculator are summarized here and explained in detail in the accompanying documentation, called Part 1 through Part 8. You'll need Adobe® Reader, version 6 or later, to read these documents.


  1. Load the necessary .NET Framework software on your computer (newer versions of Windows XP will already have the software loaded). If you need to get the .NET Framework, instructions are provided in the Part 5 document (How to Use the Calculator, PDF*, 496 KB).

  2. Download the Calculator and example files (ZIP, 620 KB).

  3. Unzip the Calculator; place all files in the same folder.

  4. Run the Calculator, WSYieldCalculator.exe, and familiarize yourself with the features and interface. The model data used on first run is contained in the climate.csv file, but you'll never have to directly access that file.

  5. Once you're familiar with the Calculator interface, read the documentation.

    The documentation gives you background on global warming and climate change, details on the modeling procedures used, model results, generalized Calculator results, examples of pilot watershed applications, analysis of impacts, potential consequences of the impacts, and possible policy implications. Also included is a discussion of appropriate and inappropriate uses of the Calculator, and its limitations (PDF*, 32 KB). This latter discussion is very important. This tool is meant to catalyze policy- and management-level dialog on the implications of climate change on watershed yield. It is not meant to be an operational-level tool. Included is a discussion of next steps to take if the risk assessment from climate change discovered through the use of this tool indicates a need for finer grained, site-specific modeling and analysis.

  6. In order to use the Calculator for your watershed of interest, you will need data for that watershed. Elevation in 500 feet intervals, vegetation type, and aspect will have to be determined for the watershed. ArcMap GIS coverages can be used in combination with ESRI's Spacial Analyst software to determine acreage of the needed Hydrologic Response Units (HRU's).


Here's a map of the study areas included in the scope of the Calculator.

Northern portion of study area includes Duncan Canyon Creek, French Meadows Reservoir, and Pilot Creek; central area includes Stanislaus River; southern area includes Bear Creek and Marble Fork.


Here's a snapshot of the Calculator interface.

Data is shown on the top describing the watershed, the left describing the area by elevation, and the results are shown on the right.


Documentation for this project was prepared by:

Otis Wollan, Project Manager
President, American River Watershed Institute
Former five-term Director, Placer County Water Agency

Project contact:

American River Watershed Institute (ARWI)
PO Box 1750
Colfax, CA 95713

Project funded by U.S. Environmental Protection Agency (EPA)