G. Lipeme Kouyi

Event-based quantification of emerging pollutant removal for an open stormwater retention basin - loads, efficiency and importance of uncertainties.

Up to now, emerging contaminants have not been further-studied in in-situ stormwater best management practices and especially in detention basins. In this article, the efficiency of a dry stormwater detention basin was investigated regarding the removal of 7 alkylphenols and alkylphenol ethoxylates, 9 polybrominated diphenyl ethers, 45 pesticides and bisphenol A. Concentrations of contaminants were obtained by chemical analysis on dissolved and particulate phase distinctly. The removal efficiency was assessed on total, dissolved and particulate phase accounting for the global chain of uncertainty with a 95% confidence interval. Results showed that pesticides (rather hydrophilic) are not trapped in the detention basin but are released contrarily to B209 which is mostly in particulate phase. Alkylphenols and alkylphenol ethoxylates are present in both phases and the efficiency is storm event-dependent. Uncertainty consideration in efficiency determination revealed efficiency data, usually presented by raw values are not relevant to conclude on the performance of a detention basin. In this case study, efficiency data with a 95% confidence interval indicate that only 35%, 50% and 41% of campaigns showed an impact (in trapping or releasing) of the detention basin on alkylphenols and ethoxylates, polybrominated diphenyl ethers and pesticides respectively.

Urban flooding: one-dimensional modelling of the distribution of the discharges through cross-road intersections accounting for energy losses

Many investigations have been carried out in order to develop models which allow the understanding of complex physical processes involved in urban flooding. The modelling of the interactions between overland flows on streets and flooding flows from rivers and sewer networks is one of the main objectives of recent and current research programs in hydraulics and urban hydrology. However, the modelling of the discharge distribution in the street network with crossroad needs further research due to the complexity of the flow through junctions. This paper outlines the ability of the improved one-dimensional CANOE software to simulate the street flows through the virtual network (developed under the Hy(2)Ville French National project framework) with several cross-roads. The improvements are done by adding in CANOE the energy losses coefficients deriving from the calibration phase based on the experimental study of the flow through small scale physical model of cross-road channels. Comparisons between 1D and 2D simulated distribution of discharges through the virtual network show a good agreement for the global distribution. However, large differences are observed focusing on the individual cross-road intersections in the virtual network.

One-dimensional modelling of the interactions between heavy rainfall-runoff in an urban area and flooding flows from sewer networks and rivers

Many investigations have been carried out in order to develop models which allow the linking of complex physical processes involved in urban flooding. The modelling of the interactions between overland flows on streets and flooding flows from rivers and sewer networks is one of the main objectives of recent and current research programs in hydraulics and urban hydrology. This paper outlines the original one-dimensional linking of heavy rainfall-runoff in urban areas and flooding flows from rivers and sewer networks under the RIVES project framework (Estimation of Scenario and Risks of Urban Floods). The first part of the paper highlights the capacity of Canoe software to simulate the street flows. In the second part, we show the original method of connection which enables the modelling of interactions between processes in urban flooding. Comparisons between simulated results and the results of Despotovic et al. or Gomez & Mur show a good agreement for the calibrated one-dimensional connection model. The connection operates likes a manhole with the orifice/weir coefficients used as calibration parameters. The influence of flooding flows from river was taken into account as a variable water depth boundary condition.

Sewer system flow components identification using signal processing.

The development of a continuous model to simulate the behaviour of sewer systems requires detailed information on each component of the flows contributing to the global discharge. In this paper authors investigate a novel method based on signal processing and long time series data implemented with a 2 min time step (flow rate, conductivity, pH and turbidity) in order to identify the dry weather components in a separated stormwater sewer system draining an industrial catchment. The wavelet analysis is applied to the recorded data to identify main components in dry weather flow after the removing of the signal noise. This paper highlights also a method to detect inflow into sewer system and shows how hydrological modelling can be used to characterise the relevant components. These techniques could be used as a basis for several applications.