Urban water quality modelling: a parsimonious holistic approach for a complex real case study

Abstract

In the past three decades, scientific research has focused on the preservation of water resources, and in particular, on the polluting impact of urban areas on natural water bodies. One approach to this research has involved the development of tools to describe the phenomena that take place on the urban catchment during both wet and dry periods. Research has demonstrated the importance of the integrated analysis of all the transformation phases that characterise the delivery and treatment of urban water pollutants from source to outfall. With this aim, numerous integrated urban drainage models have been developed to analyse the fate of pollution from urban catchments to the final receiving waters, simulating several physical and chemical processes. Such modelling approaches require calibration, and for this reason, researchers have tried to address two opposing needs: the need for reliable representation of complex systems, and the need to employ parsimonious approaches to cope with the usually insufficient, especially for urban sources, water quality data. The present paper discusses the application of a be-spoke model to a complex integrated catchment: the Nocella basin (Italy). This system is characterised by two main urban areas served by two wastewater treatment plants, and has a small river as the receiving water body. The paper describes the monitoring approach that was used for model calibration, presents some interesting considerations about the monitoring needs for integrated modelling applications, and provides initial results useful for identifying the most relevant polluting sources.

Global sensitivity analysis for urban water quality modelling: Terminology, convergence and comparison of different methods

“…The seventeen model factors reported in Table 2 have been considered. The model factor ranges have been established by considering previous model applications to different case studies (Freni et al, 2010c;Viviani, 2009a, 2010;Mannina et al, 2012). Quantity and quality model factors were changed simultaneously for each MC run.…”

“…For further details about the model and the case study the reader is referred to literature (Candela et al, 2012;Viviani, 2009a, 2010;Freni et al, 2010c).…”

Assessment of data and parameter uncertainties in integrated water-quality model

“…SSs were monitored by installing a permanent monitoring station at the SS outflow as well as a permanent station at the CSO outfall. WWTPs were monitored by permanent monitoring stations at the inflow and at the outfall to the RWB; additional temporary stations were located between biological treatment units and the sedimentation units (Freni et al 2010) Flow measurements were carried out using area -velocity probes with a 1-min temporal resolution, which allow the inflow and outflow volumes for each element in the system to be defined. Water-quality sampling was performed using automatic 24-bottle samplers and grab sampling was used for defining pollutant loads and treatment efficiencies.…”

“…All analyses were carried out according to Standard Methods (APHA 1995). The monitoring campaign was used for model calibration; the model parameters were calibrated for each of the sub-models by means of Monte Carlo Analysis, randomly varying parameters in user-defined ranges and minimising the variance of the model output errors based on the available water quantity and water quality measurements (details can be found in Freni et al 2009 andin Freni et al 2010). Initially the upstream water quantity models were calibrated; then corresponding water quality models were calibrated according to collected measures blocking water quantity parameters to the calibrated values.…”

Dynamic modelling of integrated water resources quality management

“…The history of studies on integrated water resources quantitative and qualitative management (IWRQQM) does not date back very long ago, and almost all research studies are at the urban and river scale (Burn and Yulianti, 2001;Freni et al, 2009Freni et al, , 2010aFreni et al, , 2010b. The simulation-optimisation dam operation model by Kaplan (1974) can probably be mentioned as the first serious research conducted on water resources quantitative and qualitative operation.…”