Project Background

The Willamette River Basin is a place of remarkable beauty, exceptionally productive farm and forestlands, and is home to more than two thirds of the people who live in Oregon. It also faces many changes; changes some argue are unprecedented since Euro-American settlement in the mid-19th century.

The goal of this portion of the Institute for a Sustainable Environment website is to demonstrate and make accessible a geographic framework for tracking change over space and time in the floodplain of the Willamette River. The information framework seeks to pragmatically integrate the geomorphic and hydrologic processes shaping rivers, the biological communities and processes comprising river ecosystems and the human systems guiding their land and water use trajectories. It is intended to help in making decisions about what ecosystem services to conserve or restore, where best to conserve or restore them, and how proposed conservation or restoration actions may fit into a larger guiding vision of a restored Willamette River floodplain.

In attempting to understand the Willamette River and its floodplain, the floodplain provides the most constant and quantifiable spatial framework for comparing physical, biological, and human characteristics of the river corridor. The river’s channel position, adjacent forests, and land use may all change, but the floodplain (the area historically inundated by floods) is relatively constant.  In short, this framework, oriented on the floodplain axis, provides a consistent basis for comparing changes in geomorphic structure, aquatic ecosystems and human settlement. We employ this framework for floodplain assessment by first mapping one-km “slices” of the floodplain at right angles to the floodplain’s center axis (Hulse et al. 2002; Hulse and Gregory 2004).

We refer to this spatially explicit system for tracking changes in the river and its floodplain as the “Slices Framework”. Within each of the 229 one-km slices, numbered from 0 (zero) starting at the confluence of the Willamette and Columbia Rivers to 229 at the confluence of the Middle and Coast Forks of the Willamette, we subdivide each 1 km slice into ten 100 m slices. Within these 100 m slices we measure and report characteristics that represent the dynamic processes that structure and are structured by the river and its floodplain, and that together capture key relations of ecological dynamism and resilience. In its final form, the framework will include data on channel complexity, floodplain forests, number and location of cold water refuges, native and non-native fish species richness, flood inundation, and the capacity for non-structural flood storage.

Referenced Publications:

D. Hulse, S. Gregory. 2004. Integrating resilience into floodplain restoration. Journal of Urban Ecology. Special Issue on Large-Scale Ecosystem Studies: Emerging trends in urban and regional ecology, vol. 7, pp. 295-314.

D. Hulse, S. Gregory, J. Baker. (Eds). 2002. Willamette River Basin Planning Atlas: Trajectories of environmental and ecological change. (2nd edition), Oregon State University Press, Corvallis, Oregon 97333. p. 180. The Atlas is freely available online as PDF documents.