Nighttime light imagery for mapping urban growth in Uzbekistan
Urbanization is particularly rapid in Uzbekistan, population increased during the last 60 years fivefold from around 6 million to 30 million. These tremendous changes have impacts on environment and also cause socio-economic challenges. Monitoring the spatial changes of urban development is therefore an important aspect and role of GIS, remote sensing is irreplaceable for managing these complex phenomena. Nighttime light products represent a strong evidence to evaluate human impacts on earth. This study used nighttime light imagery to explore the spatiotemporal patterns of urban growth in Uzbekistan from 1992 to 2010 using data of the nighttime light imagery. DMSP is the only satellite to study global economic and demographic changes speedily. We used a calibration method to correct images annually and then we applied threshold to extract urban growth. Results show that nighttime light enables to accurately map urban growth at country scale. Moreover, a combined analysis of lighted area and ancillary data revealed the possibility of using DMSP imagery to explore linkages to major economic parameters and showed high correlation. The relationship between lighted area and per capita income showed the highest correlation of 0.94 at the country level. Also, lighted area at the regional level has highly significant correlation value with GDP, ranging between 0.7 in case of Khorezm and 0.96 for Andijan region. Results provide a good spatial proxy for spatial distribution of urban population which is not possible to obtain from statistical sources. Overall, the findings present the great potential of DMSP imagery to map and monitor patterns of urban growth.