Land-use based stormwater pollutant load estimation and monitoring system design

Abstract

Accurate quantification of the amount, quality and sources of urban stormwater runoff are a prerequisite for effective stormwater management. The goal of this study was to estimate city-scale stormwater pollutant export, examine the effect of data sources on export estimates, and develop an optimization method for stormwater monitoring. The results were presented for the city of Lahti in southern Finland, where site mean pollutant concentrations (SMCs), annual pollutant loads, and monitoring guidelines for specific land use types were determined for total suspended solids (TSS), nutrients (total nitrogen TN and total phosphorus TP), chemical oxygen demand (COD), and metals (Pb, Zn, Cu, Cr, and Ni). Depending on the data source, differences between estimated pollutant exports ranged from -89% to 215%. Lack of reference data for every urban land use type and differences in land use classification schemes were identified as key factors limiting the accuracy of pollutant load estimation.

Keywords:

• Urban runoff
• pollutant export
• land use
• uncertainty

Acknowledgements

This study was carried out as a part of the research project ‘Urban laboratory for sustainable built environment’. Professor Heikki Setälä and M.Sc. Marjo Valtanen from the University of Helsinki are gratefully acknowledged for providing stormwater monitoring data for use in this study.