An advanced assessment of impervious surfaces (IS) in humid subtropicalregions using multi-satellite images

Principal Investigator: Prof. Lin Hui

Start Date: 2013/01/01
End Date: 2014/12/31
Type of Grant: General Research Fund

The aim of this research project is to investigate the combined use of optical remote sensing data and Synthetic Aperture Radar (SAR) data for the assessment of impervious surfaces (IS) in humid subtropical regions, including seasonal variation, and to evaluate the potential impact of IS on water quality, especially on non-point source water pollution.

With the rapid urbanization of Hong Kong and the Pearl River Delta (PRD), the spread of impervious surfaces (IS) has increased dramatically over the last two decades. It has been widely recognized that IS serves as a key environmental indicator since it affects the water cycle, water pollutants and the energy balance and, thus, relates closely to the Urban Heat Island (UHI) effect. It has also been reported that IS serves an important role in urban socio-economic studies such as detailed population distribution.

Given its importance many methods have been developed to assess impervious surfaces using satellite images, but most of the methods were tested in temperate, continental areas. Few considered the case in humid subtropical areas such as PRD, where there is significant cloud occurrence and different phenology. Due to these differences, difficulties occur when using optical remote-sensing data which is the main data source used in previous studies. Seasonal changes in vegetation, recognized as a key factor in IS estimation, create further challenges. Existing approaches need to be evaluated while additional data sources should be considered in order to establish an advanced assessment of IS in humid areas such as Hong Kong and PRD.

The outcome of this proposed research will provide evidence of the seasonal effects on IS assessment due to phenological change, evaluate the potential of SAR data for improving IS assessment and design a synergistic method to identify IS using optical and SAR images. In addition, the environmental impact of impervious surfaces on water pollution will be assessed. Since the PRD region is highly typical of many fast growing areas, the implementation of this project would serve as a model for other humid subtropical regions of the world.