Abstract

To identify the influential factors and their relative significance on spatial distribution of NO₃-N in urban groundwater, spatial analysis was conducted using GIS and statistical approaches in the Seongnae-Koduk watersheds, where rapid urbanization has been proceeded. Several factors were considered including land-use type, distance to sewage lines, the ratio of impervious surface, and the ratio of green area.  The spatial distribution of NO₃-N in the land-use types shows differences between urban and cop\rp field possibly due to the sewage networks in urban areas and the agrochemical uses in crop field. Nitrate concentrations in ground water decreased with the distance to sewage lines to approximately 60-75 m. Concentrations of nitrate and distances to sewage lines showed negative correlation, indicating that the nitrate contamination was induced from  the sewage system and specially significant in urban areas. The negative correlation of the ratio of impervious surface to the nitrate concentration inurban areas also suggested that the source materials of nitrate are introduced fromthe surface. Consequently, in areas of urbanization processes, systematic management of past-and-present land-use types and sewage systems are the most significant factors in preventing ground water from nitrate contamination.

Keywords NO₃-N, ground water, GIS, spatial analysis, influential factor