T8 Geomorphology of the Anthropocene: The Surficial Legacy of Past and Present Human Activities

Sunday, 4 November 2012
8:00 AM - 12:00 PM
207A

REMOVING STREAMS FROM THE LANDSCAPE: COUNTING THE BURIED STREAMS BENEATH URBAN LANDSCAPES

Paper number: T8-13
Program: Technical Sessions
Time: 11:05 AM – 11:20 AM

Authors

Abstract

The human influences on river systems are numerous and significant. The influences may be so severe that the river system is effectively eliminated from the landscape. Rivers have disappeared as they have been buried and the water routed through culverts and underground drainage systems to accommodate urban development. Public health concerns, improved sanitation, flood control, and the desire to increase buildable land are among the reasons that rivers were buried and removed from the landscape. However, with the spread of green infrastructure and sustainable redevelopment, renewed efforts are being made to open up these streams with the aim to incorporate them back into the essential infrastructure of the community. One of the methods to restore buried streams to a more natural state is the process of daylighting. Daylighting projects deliberately expose some or all of a previously covered river channel and liberates waterways that were buried in culverts or pipes, covered by impervious surfaces, routed into underground stormwater drainages, or otherwise removed from view. Daylighting reintegrates the river back into the urban environment, restoring biologic habitat, improving aesthetics, improving water quality with improved riparian buffers, increasing property values, and reducing urban heat island effects through increased evapotranspiration.

Historical topographic maps of northeastern New Jersey were georeferenced and digitized to identify potential daylighting projects. The digitized maps were compared to the modern stream network of New Jersey to determine where rivers used to exist. 287 buried streams were identified with a total length of 232 km. There were correlations between the number of buried streams and population density, suggesting that urban development is a significant driver of buried streams. Complete daylighting of the streams may be unrealistic due to cost, as the estimated cost of daylighting per km of buried stream is $3.1 million. One studied quadrangle map lost 126 km of streams and would require $391 million to daylight. Cost also varies by how intensely the place is urbanized, so selected sites where benefits outweigh costs could be prioritized for daylighting projects.