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Multi-scale trends analysis of landscape stressors in an urbanizing coastal watershed
Citation:
Kuhn, A. AND M. Charpentier. Multi-scale trends analysis of landscape stressors in an urbanizing coastal watershed. International Association of Landscape Ecology (IALE), Asheville, NC, April 03 - 07, 2016.
Impact/Purpose:
It is well established that anthropogenic land based stressors within a watershed can deliver major impacts to downstream and adjacent coastal waterways affecting water quality and estuarine habitats. This presentation focuses on a subset of non-point sources of watershed stressors specifically, human population density, land use land cover (LULC), impervious cover and streamflow (as an indicator of surface-water run-off). These non-point land-based stressors can be tracked over time and quantified to identify trends in landscape indicators that will allow watershed managers to measure the effectiveness of management actions.
Description:
Anthropogenic land based stressors within a watershed can deliver major impacts to downstream and adjacent coastal waterways affecting water quality and estuarine habitats. Our research focused on a subset of non-point sources of watershed stressors specifically, human population density and land use land cover (LULC). We evaluated recent trends in stressors (1985-2005) that correspond to available response data in the Narragansett Bay Watershed (NBW), one of the most densely populated watersheds in the United States. We focused on four scales to summarize and aggregate stressors across the watershed with increasing resolution: 1) the entire NBW; 2) the sub- watersheds of the six main tributaries; 3) NBW hydrological unit code (HUC) 10 sub-watersheds; 4) NBW HUC 12 sub-watersheds. This multi-scale approach allows us to analyze trends in a spatially-explicit manner and enable trends analyses to focus on specific areas of the estuary based on watershed drainage. Overall, considering gross and net LULC changes based on the combined MA and RI state-level LULC data for the 1985-2005 time period, the entire NBW experienced significant increases in urban or developed land and a concomitant loss in agricultural and forested land. Between 1985 and 2005 developed lands increased by 324 km2 or a net percentage change increase of 24.7%, while agricultural lands decreased by 124 km2 or a net percentage change decrease of 37.8%. We used a geospatial daysmetric population modeling technique with census data from 1990-2010 to estimate an overall increase of 143,049 people, a net positive change of 8.05%.