Estimating Impervious Surfaces of Gwadar City Based on the Chinese Multi-Sources Remote Sensing Images

Abstract

As the flagship of the “Belt and Road”, the development and construction of the “China-Pakistan Economic Corridor (CPEC)” are related to the common interests of the country along the line. Gwadar port, which lies at the end of the China-Pakistan Economic Corridor, is extremely important for the CPEC project. The impervious surface percentage (ISP) is an important indicator of urban development assessment and urban ecological environment evaluation. In this study, the ISP of the Gwadar city is estimated by using the Chinese high spatial resolution GF-1/2 images and fine spatial resolution HJ-1A/B images from 2009 to 2017. The growth magnitude of the ISP in Gwadar is then analyzed. Results reveal that the estimated ISP are highly reliable for detecting and characterizing change trends. The R 2 (Correlation coefficient-squared) of imitating and predicting by using Random Forest method are 0.96 and 0.76 respectively. The root mean square error (RMSE) of the estimating results are approximately 12.52%. The results indicate that there are two stages in Gwadar's impervious surface growth. First stage is that there is a period of rapid growth from 2009 to 2014. The construction of residences and roads cause the fast increase at a rate of 2.3% per year. The other stage begins with the development of the China-Pakistan Economic Corridor. The greatest growth is in the port area from 2014 to 2017, and the growth magnitude is 0.06% per year.