WATERSHED LEVEL URBAN GROWTH ESTIMATION IN TENNESSEE USING NATIONAL LAND COVER DATABASE

Urbanization transforms permeable land cover into impervious surface with the construction of roads, parking lots, and rooftops. Urbanized watersheds have been found to have significant impacts on surface water resources including degraded water quality, habitat, and ecosystems. These areas also experience increased volumes and magnitudes of floods comparing to the places in the undisturbed or rural watersheds.

Since early 1980s as a result of exponential urban growth there has been a significant change in Tennessee watershed land uses. Given this growth, to help better understand the hydrology of urban Tennessee watersheds it is important to recognize in what ways and to what extent has the urbanization of Tennessee watersheds changed since then. The National Land Cover Database (NLCD) produced by the Multi-Resolution Land Characteristics (MRLC) Consortium provides a time series of remote sensing based percent impervious surface data for the United States at 30 m spatial resolution since 1992. This study used NLCD derived percent impervious surface data from 2001 to 2011 to quantitatively estimate the urban growth in the selected cities in Tennessee. The obtained results show that all five major cities in Tennessee experienced extensive urban growth. In the areas around Nashville, Memphis, Knoxville, Johnson City, Jackson, and Chattanooga the estimated new urban areas added during this 10-year time period equal to 195, 110, 83, 46, 22, and 17 sq. kms., respectively. The 2016 NLCD data, which is expected to be released in December 2018 would provide the opportunity to update the obtained estimation of urban growth in Tennessee from 2011 to 2016. The new updated estimation will be incorporated with the geospatial watershed boundary data to generate watershed level estimation of urban growth in Tennessee. This watershed level urban growth estimation can be used as a very important input for different hydrologic, watershed, and hydrodynamic models for Tennessee water resources. The obtained results will be presented along with the future direction of this study.