Cloud to coast: integrated assessment of environmental exposure, health impacts and risk perceptions of faecal organisms in coastal waters

Abstract

The proper recognition and calculation of polluted sources and the fate and transport of faecal organisms in catchments, river networks and coastal waters are very important to the assessment of environmental exposure, health impacts and risk perceptions of faecal indicator organisms (FIO) in coastal waters. The paper reviews the integrated modelling techniques for faecal processes from cloud to coast, including sediment and faecal bacteria interactions, and then presents a theoretical and case study in the numerical modelling for FIO levels in the river Ribble and Fylde Coast using the twodimensional or three-dimensional environmental fluid dynamics code and the 1D Flow And Solute Transport in Estuaries and Rivers models, respectively. The related key parameters in the linked model are illustrated and analysed, together with validation of the hydrodynamic processes and the faecal bacteria concentration levels being undertaken using measured related data acquired in 1999. Using the model results, a quantitative microbial risk assessment is undertaken, where a moderate dose for swimming in faecal coliform-laden flows is accepted, as given by the European (EU) water quality standard requirements. The results show that some local regions of relatively high concentration exist near the outfalls and these values are not compliant with the mandatory and tighter microbial standards in the UK, as governed by the new EU Water Framework Directive. Finally, some new research and key challenges for the future are discussed in the paper.

Dynamic tracing of fecal bacteria processes from a river basin to an estuary using a 2D/3D model

“…The EFDC2D/3D code was used to study the hydrodynamic, sediment transport and FIO processes in a river, estuarine and coastal system, from the catchments to the coast. The detailed methods for grid generation, topography interpolation, bed sediment particles, bottom roughness setup are given in the references (Huang, Falconer, Boye, et al, 2015; Huang et al, 2017).…”

Integrated River and Coastal Flow, Sediment and Escherichia coli Modelling for Bathing Water Quality

“…The ratio D/Dw represents the light intensity attenuation due to sediment suspension. For conciseness, more details relating to the 1D and 2D modelling of bacteria are given in [64]. At present, the distributed hydrological model, the 1D river network model and the EFDC-2D model are all linked by data input and output as boundary conditions or point source inputs.…”

“…From these data the input FIOs or E. coli counts can be estimated for every cell, at every time step. The bathymetric data in the estuary and riverine are merged from 6 data sources and interpolated to the model nodes [64] Land and river …”