Las Vegas Metropolitan Area Urban Sprawl Assessment Using Shannon's Entropy

Abstract

A population center’s growth, known as urbanization, can pressure delicate environments and place strain on a region’s natural resources. Remote sensing combined with Geographic Information Systems can analyze and map the phenomenon of urban sprawl. This study quantifies growth within the Las Vegas, Nevada urban boundary using the aforementioned tools and Shannon’s Entropy method for 2000 and 2020. Shannon’s Entropy measures urban morphology, calculating compactness and dispersion of binary categorization, in this case, ‘developed’ and ‘undeveloped’ land cover. Eighteen multi-ring buffers were placed around Las Vegas City Hall at 1-mile intervals and found entropy values of 1.10 and 1.15 respectively. In comparison for the same years mentioned, five multi-ring buffers were set around the study area’s three main highways at 1-mile intervals and found entropy values of .608 and .628 respectively. All entropy values using the multi-ring buffer method were > 50% of log(n) for each dataset, meaning that the ‘developed’ land cover spatial variable is evenly dispersed across the study area with compactness or clustering of the ‘developed’ class found within each buffer zone. Temporally, over the 20-year period, the dispersion of development continued, with an increase in entropy values. Further, a geographic quadrant assessment revealed that the greatest land cover change-over from ‘undeveloped’ to ‘developed’ occurred in the northwestern and southwestern portions of the study area. This exercise provides a framework for developing municipalities that seek a cost effective, accessible, and expeditious method to better recognize sprawl patterns with the aim of correcting inefficient land and resource management.