URBANIZATION INDUCED CHANGES TO A RAVINE SYSTEM AND EVALUATION OF LAND USE AND INFRASTRUCTURE SUSTAINABILITY AT GRAND VALLEY STATE UNIVERSITY, ALLENDALE, MICHIGAN

Land use practices at Grand Valley State University have dramatically altered runoff, erosion, and slope stability in a ravine system adjacent to campus. This study was funded through a university undergraduate research program (Student Summer Scholars) which pairs a professor with a undergraduate student to undertake original research and present findings to fellow students and faculty. Research results will also be used to inform decision makers about erosion and sedimentation in the ravines so that future land use and facilities on the campus are sustainable.

Urbanization from campus facilities has resulted in more than 65 hectares of impermeable concrete, asphalt, and buildings. Impermeable acreage, primarily in the form of new parking lots and buildings, increased more than 16% between 1998 and 2004. The increase of impermeable surface area has resulted in decreased lag time, concentrated runoff, incision, and accelerated erosion.

Comparison of 2005 LIDAR topographic data with topographic mapping created in 1963, prior to the construction of the university, reveal consistent degradation in the heads and upper portions of some ravines of as much 4 meters; and aggradation in the lower parts of the ravines of as much as 2 meters. Degradation has created undercut slopes and slope instability, while aggradation has reduced channel slopes and buried riparian vegetation.

Early attempts to control erosion, through the installation of engineered erosion control structures, have been largely unsuccessful and in some cases have contributed to more erosion. Efforts to reduce runoff directed toward the ravines include the installation of permeable asphalt and vegetated drainage swales. Dispersal, rather than concentration, is likely to provide the best long term solution.