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Internal Spatio-temporal Dynamics of Greenspaces Influence Connectivity to Urban Landscapes
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  • Vivien Rivera,
  • Liliana Hernandez Gonzalez,
  • Colleen OBrien,
  • William Miller,
  • Aaron Packman
Vivien Rivera
Northwestern University

Corresponding Author:vivienr@u.northwestern.edu

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Liliana Hernandez Gonzalez
Northwestern University
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Colleen OBrien
Northwestern University
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William Miller
Northwestern University
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Aaron Packman
Northwestern Univeristy
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Abstract

Simultaneous pressures of climate change and increasing populations in urban areas have resulted in new stresses on stormwater infrastructure. Altered precipitation patterns require robust and versatile management strategies for stormwater, resulting in increased consideration of greenspace as infrastructure for communities with significant flood risk. There is particular interest in natural, minimally-engineered green infrastructure (GI). Such greenspaces can be heterogeneous and difficult to characterize but are often straightforwardly modelled as black-box systems within a landscape. Many natural sites cannot be approached so simply due to highly permeable interfaces with surrounding landscapes and it is often impossible to monitor the surrounds at anywhere near the same spatial or temporal resolution as within the boundaries of a study site, resulting in uncertainty about the actual benefit of natural greenspace for adjacent communities. We explored water storage in an urban green space, identifying spatio-temporal patterns of internal dynamics to holistically understand site behavior. A dense sensor network in a prairie wetland nature preserve within the Chicago metro area produced 4+ years of high-resolution surface and subsurface water level, soil moisture, precipitation, and air and water temperature data. Responses to weather events in the short term and to climate-driven seasonal effects in the longer term are then described via the combination of GIS methods and signal processing approaches. Power spectral and cross-correlation analyses contribute understanding of relevant timescales for further investigation. Applying hydrograph analysis methods to water level time series yields important statistics about the response of water table elevations throughout the prairie complex, including baseflow elevations and relaxation times. These statistics are used to develop spatial maps of event response as a function of site properties and to identify seasonal effects. Understanding the expected response of stormwater storage in a natural greenspace to a precipitation event has valuable utility for conservation groups and stormwater management utilities. The synthesis of these methods contribute to development of planning tools for siting, design, and management of GI.