Multifunctional Riverscapes: Stream restoration, Capability Brown's water features, and artificial whitewater

Society is investing in river restoration and urban river revitalization as a solution for sustainable development. Many of these river projects adopt a multifunctional planning and design approach that strives to meld ecological, aesthetic, and recreational functions. However our understanding of how to accomplish multifunctionality and how the different functions work together is incomplete. Numerous ecologically justified river restoration projects may actually be driven by aesthetic and recreational preferences that are largely unexamined. At the same time river projects originally designed for aesthetics or recreation are now attempting to integrate habitat and environmental considerations to make the rivers more sustainable. Through in-depth study of a variety of constructed river landscapes - including dense historical river bend designs, artificial whitewater, and urban stream restoration this dissertation analyzes how aesthetic, ecological, and recreational functions intersect and potentially conflict./nTo explore how aesthetic and biophysical processes work together in riverscapes, I explored the relationship between one ideal of beauty, an s-curve illustrated by William Hogarth in the 18th century and two sets of river designs: 18th century river designs in England and late 20th century river restoration designs in North America. I used two quantifiable variables, sinuosity and symmetry, to compare the ideal curve of beauty to the designed river curves. Hogarth's s-curve and river restoration meanders had symmetrical curves. Symmetry in restoration designs represents a theoretical condition and is counter to how most natural rivers meander. A second aesthetic-ecological study examined whether 18th century English landscape design represents design with nature. By tracing the persistence of Capability Brown's river designs over the past two centuries, the results show Brown's designs required maintenance and are not self-perpetuating as expected of a design based on natural processes./nTo evaluate the intersection of recreation and ecological functions, I conducted a case study of three urban river projects, a historical study of artificial whitewater designs, and an observational study of summertime whitewater park use. By comparing the ecological and social impacts of three urban river projects (Cheonggyecheon in Seoul, South Korea, the South Platte Greenway in Denver, United States, and the Isar River in Munich, Germany), one emerged as moving towards multifunctional planning and design. The Isar River project was unique because the planners and designers used a dynamic guiding image, gave the river room to roam, and allowed some dynamic biophysical processes to occur. The selection of the guiding image for the Isar restoration was fortuitously a publicly valued stream reach for its aesthetics and existing recreational use. The South Platte Greenway, which contains a whitewater park, illustrates a riverscape made primarily for recreation. The history of artificial whitewater designs evolved since the 1970s to a point in 2000 when the Sydney Olympic Whitewater Course was disconnected from a stream to create a fair playing field for competitors where all of the whitewater variables could be controlled. Meanwhile, instream whitewater parks began to include habitat and fish passage considerations in the engineered wave structures. Observations of whitewater park use and surveys of park user's perceptions of the parks revealed that kayakers represent only a small fraction of park users and overall use evinced no clear relationship to streamflow but varied with air and water temperature. Summer streamflow provisions for whitewater parks potentially limits the diversity of instream users and the ecological function. While whitewater park users value clean water as the most important characteristic, all interviewed park users wanted the park to have a natural appearance, but they did not mind seeing concrete in the river./nUnderstanding the patterns of recreation and perceptions of rivers in relation to biophysical processes such as streamflow or channel pattern is fundamental to achieving sustainability. The forms that people prefer--perhaps because they are beautiful--and a local-level understanding of recreational use need to be considered alongside the physical and ecological patterns and processes of rivers, the domain of landscape ecology and river science. Combining ground level research and perception studies with environmentally based landscape planning can create multifunctional landscapes. For previously impacted rivers in developed areas, multifunctional riverscape planning and design offers a sustainable development solution.

Advisor: Kondolf, G. Mathias