Mapping urban growth and investigating its potential impact on surface water quality in Chattanooga, Tennessee using GIS and remote sensing

Urban development involves the conversion of land cover from pervious to impervious surfaces. Impervious surfaces (IS) can have ramifications for urban stormwater and facilitate the movement of pollutants and other substances to nearby water bodies. This study investigated the changes in IS in and around the city of Chattanooga, Tennessee using GIS and remote sensing technologies based on Landsat 5 Thematic Mapper (TM) and Landsat 8 Operational Land Imager (OLI) acquired in 1986 and 2016, respectively. A model was developed utilizing the Normalized Difference Vegetation Index (NDVI) and a supervised image classification algorithm to detect IS growth. The changes in IS were quantified at watershed level scale including stream riparian areas. The obtained results show a net growth of 45.12 km2 of IS, 9.96 km2 being within 90 m of streams, a conversion of 6% of the study site’s land cover. A stream risk assessment study was conducted using the riparian zone percent imperviousness to assess the potential of stream impairment due to IS growth. This assessment shows a significant increase in the number of streams that are potentially at risk to be impaired due to current urban growth