Leveraging an Urban Flood Management Tool for Event Forecasting

A small creek that runs through the northwest corridor of the City of Toronto often floods during heavy rainfall events. This is due to both the intense rainfall accumulation and potential backups and sanitary sewer overflows (SSOs) in the sanitary sewer network. To minimize the effects of this flooding events, Toronto Water implemented a digital urban flood management tool for flood event monitoring, quantification, and forecasting. This tool acts as an early warning system that enables Toronto Water to predict and quantify flood events, which in turn, allows them to proactively manage the sewer system to reduce flooding and overflow events during these rainfall events. The solution leverages real-time and historical data from sensors throughout the sewer network near the creek, integrates this data with a hydraulic model of the sewer network and combines it with meteorological weather service data and hydrological data of the creek to, then, perform advanced analytics to quantify and forecast potential flooding events during wet weather events. Toronto Water uses the results of this tool to provide its staff members with alerts for potential flooding and sewer overflow events, enabling them to proactively manage their system. In addition to the early warning system alerts, this tool integrates a real-time weather forecast map and provides real-time and forecasted data that is viewed in real-time visualization maps enabling users to monitor and identify flooding and overflow events. This decision support system helps Toronto Water ensure optimization of sewer system capacity during wet weather events. Methodology, Approach, & Results Toronto water uses XVPGA's urban flood management solution for urban flood event monitoring and forecasting. This digital solution obtains and process information from different data sources from Toronto Water and other City of Toronto's agencies, it also includes Toronto Water's GIS of the sewershed network, data from the sanitary sewer flow meters and level sensors installed by Toronto Water, weather data from the Meteorological Service of Canada (MSC) and Toronto Water rain gauge stations, a hydraulic model of the sanitary sewer network, and hydrological data of the nearby creek. Leveraging this input data, the urban flood management tool performs analytics to provide hydro-meteorological forecasting and overlays this data on a real-time visualization and forecasting map. In addition, this tool also provides Toronto Water users with the ability to perform 'what-if' scenarios to analyze potential flooding and overflow events based on estimated (user input) rain accumulation and intensity levels. The main analytical components included in this tool are:

*Hydro-meteorological Forecasting Maps for the estimation of fluvial flow rates based on real-time hydrological models and visualization maps. In addition, rainfall maps for aerial interpolation using geostatistical methods are created. Toronto Water uses these maps for visualization and quantification purposes to complement the analytical data outputs of the Real-time Early Warning System and Early Warning Prediction System.

*Real Time Early Warning System provides flood event warnings based primarily on real-time sensor data, from both the sewer level monitors, rain gauges, and MSC weather data. This is a short-term alerting system that provides alerts of expected time to flood events and potential overflows in the near future. This early warning system enables Toronto Water to proactively manage the sewer system in real-time, dispatching field crews to the most critical points in the system to help manage the system in a way that will reduce flooding levels and eliminate potential overflows.

*Early Warning Prediction System for the prediction of urban flooding and overflow events over the next 24 hours, at any point or area within the sewershed, based on analytics of rainfall forecasts and hydrological modeling data. Similar to the real-time early warning system, but forecasting events over a longer future period, Toronto Water leverages this tool to proactively management the sewer system in preparation for potential flooding events. As this digital tool enables Toronto Water to predict urban flood events and potential overflows within the sanitary sewer network, they are leveraging the tool to optimize decision making and implement early activation protocols and improve decision-making processes for system management by developing coordination plans. In addition, to these analytical components, Toronto can leverage the 'what-if' scenario functionality of the tool to estimate the magnitude of flooding events based on different rainfall scenarios. This functionality enables them to simulate scenarios based on varying (heavier) rainfall events that are predicted to ensure there is sufficient system capacity and their system management plan is optimal in each case.