Innovative modeling of the physicobiochemical determinants of fecal indicator bacteria

“The risk of infection by enteric pathogens in bathing waters is generally indicated by monitoring fecal indicator bacteria (FIB) concentrations. Mechanistic models are efficient tools for predicting FIB concentrations and corresponding contributions from various impact factors based on historical records and different climatic scenarios. However, most existing FIB physicobiochemical models are limited by the availability of FIB observations and knowledge of the physicobiochemical processes. Modeling studies that performed advanced sensitivity analyses or model comparisons to disentangle the contributions from different processes and impact factors, are rare.

To enhance the understanding of the relative importance of the various processes that affect FIB concentrations in different aquatic systems, we developed a comprehensive and generic FIB physicobiochemical model, including an improved die-off module and sediment interaction module. The new die-off module includes a cumulative endogenous photo-inactivation. By developing the relationship between dissolved organic carbon (DOC) concentrations and Ultraviolet diffuse attenuation coefficients, the module calculates the Ultraviolet-A (UVA) and Ultraviolet-B (UVB) extinction by waters. The penetrated UVA + UVB light under different wavelengths is used for endogenous photoinactivation rate calculation via the biological weighting function. Distinct from using a constant partition rate in previous sediment interaction modules, the new sediment interaction module calculates the dynamic partition rate based on not only suspended sediment (SS) concentrations but also its composition via two different classes of SS: sand and clay.”

(Citation: Wang, H., Blauw, A., van Gils, J., Boelee, E., and Medema, G.: Innovative modeling of the physicobiochemical determinants of fecal indicator bacteria, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10607, https://doi.org/10.5194/egusphere-egu25-10607, 2025)

© Author(s) 2025. This work is distributed under the Creative Commons Attribution 4.0 License.