Statistical evaluation of intra-event variability of fecal indicator in stormwater runoff from different land uses

Abstract

Stormwater runoff is one of the major transporters of fecal indicator bacteria (FIB) contaminant in the downstream areas. The development of models to predict FIB concentrations in stormwater runoff are important because it is impractical to monitor and analyze every different microorganism at all monitoring sites. Understanding the correlation of hydrological characteristics such as antecedent dry days (ADD), total rainfall (RAIN), average rainfall intensity (AVGINT), runoff duration (RUNDUR) and runoff volume (RUNVOL), is important in development of such models. In this study, the samples were collected from three different monitoring sites which include agriculture (Site 1); mixed catchment (Site 2) and urban (Site 3). Results demonstrate that Site 1 showed low levels of FIB concentration; however, concentration levels for the samples collected during intra-event flow (initial, peak and final) exceeded the regulatory threshold limits for either safe drinking or recreational purposes in all monitoring sites. The Pearson correlation coefficient between Escherichia coli (EC) and Fecal Streptococcus (FS) showed statistically significant. Multiple linear regression analysis (MLR) was used to determine the dominant factors that affect the FIB concentrations. Based on MLR analyses, the result suggest that, ADD, AVGINT and RUNDUR were significantly affects the intra-event FIB concentrations in the study area.