American River Watershed Institute

Sierra Climate Change Watershed Yield Calculator — Documentation

This page describes the documentation available for the Calculator and provides links to download that documentation. To get the Calculator itself, see the Instructions.

Documentation is segmented into eight parts. Each of those parts is described briefly here. Click on the link to a specific part to download it.

This compilation, drawn from many of the major scientists who focus on climate change in California, provides background on the effect of greenhouse gases, and a overview of climate change, from Global Climate Models (GCM's) to regional models that predict effects to the Sierra Nevada. One of the best additional resources is the California Climate Change Portal (California Energy Commission), which will lead to many other CEC pages, including new research , CEC's 2004 event, and its 2005 event.

Part 1 was compiled by Otis Wollan, American River Watershed Institute (ARWI) using material drawn from presenters at the CEC conferences, and was influenced mainly by a presentation given at ACWA, December 2004, by Phil Duffy, PhD, of UC Merced and Lawrence Livermore Laboratories.

This document gives detail on how the HSPF model was applied for this project. John Humphreys' paper provides greater detail on the model: Influence of Climate Change on Watershed Yield (PDF*, 684 KB). The HSPF program was used to model six subwatersheds in the Sierra, which are included with the Calculator. Three watersheds were used for model calibration: Duncan Canyon in the North, South Fork Stanislaus River in Central, and Bear Creek in the South (DUNC.XML, STAN.XML, & BEAR.XML). Three pilot watersheds were also modeled: French Meadows and Pilot Creek in the North, and the Marble Fork of the Kaweah in the South. (FRENCH.XML, PILOT.XML, & MARBLE.XML). These XML files can be loaded directly by the calculator, using the File>Open sequence from the top bar menu of the calculator interface.

The documents, the Calculator, and the XML files from the model in Part 2 were created by John H. Humphrey, PhD, Hydmet Inc., who did all the HSPF modeling for the project.

Examples of model results are shown in this document.

This presentation was created by John H. Humphrey, PhD, Hydmet Inc.

Regional model results were generated using Calculator results, shown in this document.

Also included in Part 4 is a discussion of appropriate and inappropriate uses of the calculator (PDF*, 32 KB).

Hydrologic implications are summarized in a notes version of a PowerPoint presentation, Sample Model Results by Study Region Using Equal Weighted HRU's (PDF*, 136 KB).

The files in Part 4 were created by analyst Chuck Watson, WRC Environmental.

Go to this part first in order to get instructions on downloading the required .NET Framework software, and descriptions of the features of the Calculator interface.

This document profiles Calculator results for two watersheds in the Northern Region of the Sierra Nevada. Calculator results are shown for all calibration and pilot watersheds. For example, see French Meadows data output (PDF*, 272 KB), Bear Creek data output (PDF*, 480 KB), or South Fork Stanislaus data output (PDF*, 616 KB) files. The Calculator was used to generate a scenario profile of the whole watershed and watershed yield impact that would occur from 1-4 degree C increases, and an elevation profile of the 4 degree C scenario. Precipitation was not changed from baseline in either scenario. An Excel file was then used to create the graphs of changes to Average, Wet and Dry years. Each watershed (French Meadows, South Fork Stanislaus, Bear Creek, Marble Fork Kaweah, Pilot Creek) has its own Excel file for graph data (ZIP, 52 KB).

Part 6 was created by Otis Wollan, American River Watershed Institute.

This overview of local impacts is meant to catalyze dialog about what kinds of impacts might occur in Sierra watersheds. This discussion is not meant to predict these impacts on all watersheds. It is important for anyone using the Calculator to look at the results specific to that individual watershed. The descriptions of these potential impacts grew out of the results from the two watersheds profiled in Part 6.

Part 7 was created by Otis Wollan, a former five-term Director of the Placer County Water Agency (PCWA). French Meadows Reservoir is part of PCWA's Middle Fork American River system.

Policies and governance implications of climate change are subjects of a dialog in its infancy. This is a viewpoint offered by Otis Wollan, an elected water agency official whose district is directly and seriously affected by climate change; the opinions are from the individual, and do not necessarily reflect the views or policies of PCWA, Hydmet, or WRC Environmental. The purpose of this section is to attempt to take a high altitude view of what policy shifts may be happening or likely will happen in response to the eminent period of climatic change that will alter the way water is managed in California. This is meant to catalyze debate and discussion. Please send your views or reviews to

Created by Otis Wollan for presentation to the Association of California Water Agencies (ACWA) at the December 2004 Conference.