Geoscience Reference
In-Depth Information
Chapter 9
Exploring the Spatially Varying Impact
of Urbanization on Water Quality in Eastern
Massachusetts Using Geographically Weighted
Regression
Jun Tu
Abstract
The impact of urbanization on water quality might vary over space
because watershed characteristics, pollution sources, and land use patterns are not
the same in different places. However, the spatially varying impact is usually not
considered using conventional statistical methods, such as ordinary least squares
regression (OLS) and Spearman's rank correlation analysis. This study applies a
geospatial statistical technique, geographically weighted regression (GWR), to ana-
lyze the relationships between urbanization and water quality indicators across
watersheds with varied urbanization levels in eastern Massachusetts, USA. The
study finds that the relationships between water quality and urbanization indica-
tors vary across the urbanization gradient in the studied watersheds. Percentage
of developed land and population density are more strongly related to concentra-
tions of water pollutants in less-urbanized areas than in highly-urbanized areas.
The adverse impact of urbanization on water quality is more substantial in less-
urbanized suburban areas than highly-urbanized central cities, which is associated
with the dominant pattern of urbanization in the study area: urban sprawl. The study
suggests that GWR is a useful geospatial technology for policy makers, regional
and local agencies, and researchers to unveil the local pollution causes, to improve
the understanding of local pollution status, and to adopt appropriate environmen-
tal and land use planning policies suitable to the local watershed conservation and
management.
Keywords
Geographically weighted
regression
·
Water
quality
·
Urbanization
·
Urban Sprawl
