Implementation of an early warning system in urban drainage infrastructures for direct discharges and flood risk management

Abstract

Combined sewer systems are often unable to respond adequately to rising water volumes draining from urban areas during rainfall events, resulting in frequent direct discharges into receiving waters and floods, with severe environmental and economic impacts. Despite stricter legislation on pollution control and flood risk assessment, there are still some challenges regarding the development of early warning systems based on water quality issues and fully integrated models. An innovative, real-time urban warning system for flooding and pollution events was built for the Alcântara basin (the largest in Lisbon), to provide timely information to wastewater management entities and to civil protection services. The platform provides real-time access to monitoring data and, based on 48-hour precipitation forecasts, predicts the performance of the system through the integrated use of mathematical models for both drainage network and estuary. Predictions are automatically compared and validated with on-line data. This paper presents the overall design of the system and main results obtained thus far. The analysis of the system shows the ability of the integrated models to represent the main spatial and temporal patterns observed, effectively predicting the system response to precipitation events and estimating volumes discharged into the water bodies and their average pollution loads. Furthermore, the overall results strongly indicate UV-Vis spectra to be reliable for TSS and COD estimation in sewer systems.