Author(s): Man Yue Lam; Reza Ahmadian; Roger Falconer

Linked Author(s): Man Yue Lam, Reza Ahmadian

Keywords: Hydro-environmental model; Particle tracking model; Swansea Bay; Feacal bacteria source; Water quality management

Abstract: Coastal and riverine waters can be impaired in many ways. One of the main contaminants of waters used for drinking, aquaculture and recreation is pathogenic microbes. Pathogens in bathing water concerns water engineers and environmental managers because it could cause health issues to people who are using the bathing water sites. Faecal Indicator Organisms (FIOs), which indicate the presence of faecal pathogens, have been used to define the legal compliance status of bathing waters in the European revised Bathing Water Directive (rBWD) 2006/7/EC. Measuring FIOs in water samples, while provides data for beach legal compliance status, does not give sufficient spatial-temporal information required for bathing water quality management and decision making. While data-driven models provide computationally fast water quality forecasts as well as key explanatory variable identification, the models do not provide information on the main contaminant sources for a particular bathing water site. Hydro-environmental models can be used to identify connectivity between contaminant sources and receptors, e.g. identifying significance of Waste Water Treatment Works or agricultural lands on bathing water and aquaculture sites. Source-receptor connectivity describes causal relationships between sources and receptors and allows water quality improvement measures to be targeted at major sources. This research implements hydrodynamic models to identify the connectivity between bacteria sources and bathing water sites located around Swansea Bay, located on the North of the Bristol Channel on the Southwest of the UK. Swansea Bay is selected as the case study due to large number of sources, i.e. 85 different sources, including surface water and waste water treatment work discharges, which were sampled at 15 minute intervals over the bathing season (May - September). Selection of data rich case study with various sources provided the opportunity of rigorous model validation and testing. The hydrodynamic modelling is conducted with a finite-element opensource hydrodynamic solver TELEMAC. The solver has been successfully applied in a wide range of waterbodies including Loughor Estuary, UK and the beaches of Anglet, France. Tracer bacteria are released at the key sources such as river inputs. Numerical results are compared to available field data to validate the models and evaluate the factors governing bacterial transport. The connectivity between the main receptors, i.e. bathing water sites, and various sources is identified. This knowledge helps management of the bathing water sites to maintain low level of contaminants on those sites. This study is a part of the EERES4WATER project, which develops the technology and management strategies to overcome the Energy-Water nexus challenges.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022535

Year: 2022