A preliminary study on impervious surface area dynamics and water quality response at watershed scale

Impervious surface areas (ISA) play an important role in determining the water quality of the receiving waters. Remote Sensing, Geographical Information System, and multiple regression techniques were coupled in this study to detect the impervious surface area dynamics over the last 20 years and the linkage between ISA and Chemical permanganate index (CODMn), Ammonia (NH4+-N), and total phosphorus (TP) concentrations in a coastal watershed, Southeast China. Multitemporal Landsat TM images of 1986 and 2007 were used to extract ISA based on the scaled normalized difference vegetation index (NDVIs). ISA and three water quality parameters (CODMn, NH4+-N and TP) for 17 sub-watersheds of the Jiulong River basin were further extracted and collected so as to assess the relationship between ISA and water quality at watershed scale. The results show ISA has been noticeably increasing in terms of sub-watersheds in the last 20 years. CODMn, NH4+-N and TP were all moderately strongly (r2= 0.396-0.595) and significantly (p=0.000-0.007) correlated with percentage of ISA. The findings in this study are supposed to gain better understanding on linkage between urbanization and water quality at watershed scale.