Project Title: Evaluation of Watershed Response to Land Use Changes

Investigator: Mary Ann Madej USGS-BRD Redwood Field Station Arcata, CA USA 707-464-6101 Ext. 5490 FAX: 707-822-8904 mary_ann_madej@usgs.gov Partners: US Forest Service Redwood National and State Parks Arcata, CA USA 707-464-6101
	Widespread ground disturbance resulted from past timber harvest in north coastal watersheds. Watershed response to changing land use conditions are modeled in this project.

You may download a Powerpoint Presentation on watershed modeling by right-clicking below and selecting Save As...
Watershed Presentation

Project Description:
Because Redwood National Park lies at the downstream third of a watershed that is primarily being managed for timber harvest, it is vulnerable to outside threats from erosion and sedimentation. Park management needs a tool by which to evaluate the effects of changing forest practices and road construction techniques on downstream park resources (old growth redwoods and aquatic habitat). The park has a long-term data set based on water and sediment discharge monitoring, field data, and a mature GIS. It is now possible, with this knowledge of how the system works, for the USGS-BRD and the park to formulate a predictive tool to assess different scenarios of land use and floods in the upper basin. Several agencies (U.S. Forest Service, National Weather Service, California Department of Forestry) are interested in participating as partners in this venture. The information generated will be used in timber harvest plan reviews and in prioritizing erosion control projects.

Purpose:
The purpose of the research is to evaluate future damage to aquatic and riparian resources in north coastal California under different timber harvesting and road building scenarios, coupled with a probability analysis of floods of various magnitudes. The proposed evaluation will provide a basis to assess many aspects of the President's Northwest Forest Plan.

A watershed model will not only identify the terrain most sensitive to timber harvest, but will be able to evaluate different logging and road construction strategies and their impacts on aquatic habitat.

Progress/Results:
An extensive review of existing reports and data sets involving precipitation, water and sediment monitoring, timber harvest, road construction, vegetation changes and erosion inventories is in progress. Several GIS themes have been prepared: landslide history, vegetation type, timber harvest history, road location and construction, hydrography, property boundaries, hillslope gradients, soils and geology.

Products - Completed:
Department of the Interior. 1997. Draft Redwood Creek Watershed Analysis. Division of Resource Management and Science, Redwood National and State Parks. Arcata, California. 81 p.

Planned:
The first part phase will be to identify terrain susceptible to damage from various land use activities. This phase will evaluate what changes in the watershed will trigger stream flow changes and erosion under different scenarios of timber harvest, road construction and storms. The second phase is to construct a sediment routing model, which will quantify sediment sources in the watershed, and how much and how fast that sediment is transferred downstream to park river reaches. This will help convince state agencies and private landowners of the impacts of upstream land use on downstream park resources, and can be used as a guide for future management activities. The third phase will link the first two in a management tool that can predict probabilities of future damage to park resources under changing hydrologic regimes and changing land use. Forest management on private lands is presently in a state of flux, and the change in timber harvest techniques may have profound implications for downstream park lands.

Keywords: watershed, model, sediment routing, floods, land use, Northwest Forest Plan