Abstract. Combined sewer overflows (CSOs) affect bathing water
quality of receiving water bodies by bacterial pollution. The aim of this
study is to assess the health hazard of bathing waters affected by CSOs.
This is useful for bathing water managers, for risk assessment purposes, and
for further impact and economic assessments. Pollutant hazard was
evaluated based on two novel indicators proposed in this study: the mean
duration of insufficient bathing water quality (1) over a period of time
(i.e., several years) and (2) after single CSO/rain events. In particular, a
novel correlation between the duration of seawater pollution and the event
rainfall volume was developed. Pollutant hazard was assessed through a coupled urban drainage and seawater quality model that was
developed, calibrated and validated based on local observations.
Furthermore, hazard assessment was based on a novel statistical analysis of
continuous simulations over a 9-year period using the coupled model.
Finally, a validation of the estimated hazard is also shown. The health
hazard was evaluated for the case study of Badalona (Spain) even though the
methodology presented can be considered generally applicable to other urban
areas and related receiving bathing water bodies. The case study presented
is part of the EU-funded H2020 project BINGO (Bringing INnovation to OnGOing
water management – a better future under climate change).
Modeling of <i>E. coli</i> distribution for hazard assessment of bathing waters affected by combined sewer overflows