Author(s): Aisling Corkery; John O'Sullivan; Louise Deering; Katalin Demeter; Elisenda Balleste; Bat Masterson; Wim Meijer; Gregory O'Hare
Linked Author(s): John D. OSullivan
Keywords: Catchment Modelling; Microbial Source Tracking; Human Gene Marker; Water Quality
Abstract: The ability to model the transport of source specific faecal bacteria contamination in river networks can equip water resource managers with information of the different pathogens that are present. Such information can be particularly useful in catchment management plans for rivers from which potable water is extracted or where these rivers discharge to coastal zones where bathing or aquaculture is prominent and where the evaluation of human health risks is of primary importance. This paper presents an application of the MIKE11 Hydrodynamic model for evaluating the fate of faecal bacteria from human sources within the Dargle catchment, on the east coast of Ireland. The Dargle is a spate river and the upper catchment is characterised by steep slopes that incorporates peat bogs and land used for forestry and agricultural purposes. Residential dwellings within the area are predominantly single detached units that rely on septic tanks for wastewater treatment and in the context of faecal bacteria of human origin, malfunctioning systems are of concern. The MIKE11 model was calibrated in a two stages process. Firstly, the model was calibrated for prediction of discharge and microbial water quality parameters, namely E. coli and Intestinal Enterococci (IE), using data from a real-time sensor network within the catchment that comprised rain gauges, weather stations and water level recorders, data from which was used to determine flow records from stage-discharge ratings. E. coli and IE concentrations were determined from high resolution sampling during storm events. Following this, water quality samples taken during storm event sampling were used to identify and quantify the human gene marker HF183f using quantitative polymer chain reaction (q PCR) techniques. Results from the q PCR analysis were used to further calibrate the model at sub-catchment level for the transport of microbial bacteria derived from human origins. Domestic sources have been calculated based on the number of septic tank units and average daily faecal gene marker concentrations per household. Results indicate that the MIKE11 model, when calibrated, can model the transport of source specific faecal bacteria. In addition to presenting and discussing these results, the paper highlights the uncertainties in the modelling of source specific faecal contamination.
Year: 2014