MODELLING FATE AND TRANSPORT OF ESCHERICHIA COLI AND CRYPTOSPORIDIUM SPP. USING SOIL AND WATER ASSESSMENT TOOL

Paper in proceeding, 2015

Maintaining good quality of drinking water sources is essential as a part of drinking water management. Lately, microbial organisms originating from faecal contamination have been increasingly identified as a health risk and as an issue for providing safe drinking water. In Sweden, Lake Malaren is a drinking water source for two million people. The aim of this study was to set up, calibrate and validate a hydrological model using the Soil and Water Assessment Tool (SWAT) for a catchment area draining to Lake Malaren in order to simulate transport and fate of faecal contaminants in the form of Escherichia coli and Cryptosporidium spp. oocysts. Furthermore the applicability of using the SWAT model for simulating transport and fate of faecal contamination in this area will be evaluated. Sources of faecal contamination were identified through literature studies and contacts with local authorities. Model calibration n was performed on water flow in three different sub-basins using SWAT-CUP. It showed an Nash-Sutcliffe Efficiency (NSE) between 0.18-0.44 and R-2 between 0.26-0.53, whereas validation resulted in an NSE between 0.05-0.1 and R-2 between 0.10-0.16. The modelling results showed that wastewater treatment plants were the dominating source of faecal contamination. Temporary spread of manure could also be seen as an important contributor. Catchment outlet concentrations of E. coli were higher than acceptable for Swedish bathing water quality, and the concentration of Cryptosporidium spp. oocysts were in the same range as reported in other studies.