Numerical modeling of microbial fate and transport in natural waters: Review and implications for normal and extreme storm events

Abstract

Degradation of water quality in recreational areas can be a substantial public health concern. Models can help beachmanagersmake contemporaneousdecisions to protect public health at recreational areas, via the use ofmicrobial fate and transport simulation. Approaches tomodelingmicrobial fate and transport vary widely in response to local hydrometeorological contexts, but many parameterizations include terms for basemortality, solar inactivation, and sedimentation ofmicrobial contaminants. Models using these parameterizations can predict up to 87% of variation in observed microbial concentrations in nearshore water, with rootmean squared errors ranging from0.41 to 5.37 log10 Colony Forming Units (CFU) 100 mL-1. This indicates that some models predict microbial fate and transport more reliably than others and that there remains room for model improvement across the board. Model refinement will be integral to microbial fate and transport simulation in the face of less readily observable processes affecting water quality in nearshore areas. Management of contamination phenomena such as the release of storm-associated river plumes and the exchange of contaminants between water and sand at the beach can benefit greatly from optimized fate and transport modeling in the absence of directly observable data.