Aligning Scales in Social and Environmental Elements of Urban Green Infrastructure
Citation:
Herrmann, D., A. Berland, AND W. Shuster. Aligning Scales in Social and Environmental Elements of Urban Green Infrastructure. 2019 Association of American Geographers Annual Meeting, DC, Washington DC, April 03 - 07, 2019.
Impact/Purpose:
We have developed a model of urban landscape form (i.e., topography and composition of the landscape) to better understand how water moves through urban and post-urban vacant areas. Since all of these types of urban spaces receive rainfall, having a more general sense of how water moves through these landscapes is key to the management of stormwater runoff, and regulating its impact on wastewater systems. This model is also a new perspective on green infrastructure and how we might view the existing urban landscape as such. Our work supports the Clean Water Act, and will assist municipalities in managing their water resources in a more integrated way.
Description:
A common intended function of green infrastructure is management of urban ecosystem water cycles. The shape of land, specifically its hillslopes, within watersheds regulates the movement of water from uplands to streams. Thus, managing water cycling within watersheds requires working with hillslope processes. Earth-moving activities of urbanization re-sculpt historical hillslopes around the political, built, and natural elements of urban landscapes. Therefore, managing urban water cycles with green infrastructure requires understanding how urbanization transforms the physical form of hillslopes and how these changes orient hillslope form around political (e.g., parcel boundaries) and built (e.g., houses, roads) elements. We found that urbanization is associated with a convergence on gentle slopes (3-5%) as watershed averages. Urbanization also shortened the length of hillslopes – decreasing the distance between water-contributing and water-collecting areas of the landscape resulting in smaller, more disaggregated hillslope complexes – when compared to hillslopes in reference watersheds that were not urbanized. The shortened hillslopes were oriented around parcel boundaries and transportation rights of way in addition to pre-existing terrains. Results indicate urban green infrastructure planning for retrofitting existing urban landscapes needs to consider small and disaggregated hillslope complexes scaled to the parcel-street grid system. Forward-thinking planning could consider how political boundaries and infrastructure networks might work with the scale of hillslopes that exist prior to urbanization to decrease destruction of soils from earth-moving and maintain pre-existing hydrologic connections.