Mapping Urbanization and Evaluating Its Possible Impacts on Stream Water Quality in Chattanooga, Tennessee, Using GIS and Remote Sensing

Jonah Hall,A K M Azad Hossain

doi:10.3390/su12051980

Abstract

Impervious surfaces (IS) produced by urbanization can facilitate pollutants’ movement to nearby water bodies through stormwater. This study mapped and estimated the IS changes in Chattanooga, Tennessee, using satellite imagery acquired in 1986 and 2016. A model was developed utilizing the Normalized Difference Vegetation Index coupled with density slicing to detect and map urbanization through IS growth. Urban growth was quantified at USGS HUC12 watershed level including stream riparian areas. The obtained results show a net growth of 45.12 km2 of IS with a heterogeneous distribution. About 9.96 km2 of this growth is within 90 m of streams, about 6% of the study site’s land cover. The Lower South Chickamauga Creek watershed experienced the largest urban growth with a change from 24.2 to 48.5 km2. Using the riparian zone percent imperviousness, a stream risk assessment model was developed to evaluate potential stream impairment due to this growth. Approximately 87, 131, and 203 km lengths of streams identified as potentially at high, very high, and extreme risks, respectively, to be impaired due to urban growth from the last 30 years. These findings would benefit to proactively implement sustainable management plans for the streams near rapidly urbanizing areas in the study site.

Highlights

Urban areas are often defined by anthropogenically created impervious surfaces such as concrete, asphalt, and metal [1,2]
Remote sensing data acquisition have the ability for routine temporal data collection of the same area of interest, which allows for more efficient change detection analyses [86]
Downtown Chattanooga lies directly adjacent to the Tennessee River, and has several major parks and trails following along the rSiuvsetarifnraobinlitt.y T20h2e0,p12a,rxkFs,OaRloPnEgERwRiEthVIoEtWher attractions such as the 120-million-dollar downtown River6woaf l4k9, have earned Chattanooga multiple national awards for the best outdoor city [123,124]

Summary

Introduction

Urban areas are often defined by anthropogenically created impervious surfaces such as concrete, asphalt, and metal [1,2]. As of 2014, contain 54% of the global population and are estimated to increase to 66% by 2050. The rates of urbanization are not globally uniform. In North America, 82% of the population resides in urban areas compared to other continents such as Africa and Asia with 40% and 48%, respectively. The fastest growing areas are in Africa and Asia and are estimated to increase to 56% and 64%, respectively, with more urbanized areas such as Northern America growing at slower rates [3]. While slower than other areas globally, North America, and the continental United States, is still experiencing significant growth both in urban population and urban development

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