A generalised Dynamic Overflow Risk Assessment (DORA) for Real Time Control of urban drainage systems

Abstract

An innovative and generalised approach to the integrated real time control of urban drainage systems is presented. The Dynamic Overflow Risk Assessment (DORA) strategy aims to minimise the expected Combined Sewer Overflow (CSO) risk by considering (i) the water volume presently stored in the drainage network, (ii) the expected runoff volume (calculated by radar-based nowcast models) and -most important -(iii) the estimated uncertainty of the runoff forecasts. The inclusion of uncertainty allows for a more confident use of Real Time Control (RTC). Overflow risk is calculated by a flexible function which allows for the prioritisation of the discharge points according to their sensitivity and intended use. DORA was tested on a hypothetical example inspired by the main catchment in the city of Aarhus (Denmark). An analysis of DORA's performance over a range of events with different return periods, using a simple conceptual model, is presented. Compared to a traditional local control approach, DORA contributed to reduce CSO volumes from the most sensitive points while reducing total CSO volumes discharged from the catchment. Additionally, the results show that the inclusion of forecasts and their uncertainty contributed to further improving the performance of drainage systems. The results of this paper will contribute to the wider usage of global RTC methods in the management of urban drainage networks.

Coordinating Rule-Based and System-Wide Model Predictive Control Strategies to Reduce Storage Expansion of Combined Urban Drainage Systems: The Case Study of Lundtofte, Denmark

“…This predictive approach applies a global, system-wide risk-based optimization strategy, called Dynamic Overflow Risk Assessment (DORA) [16], which combines actual measurements from the system (in this case, states were simulated with the MU model), rainfall-runoff forecasts, and the uncertainty of these forecasts. DORA minimizes a global risk function, which is calculated as:…”

“…In this case, the monetary value of overflow, expressed by the risk factor R i , was defined as an arbitrary value, reflecting the different sensitivity of the different discharge points (see Section 2.4.2). A constant forecast uncertainty was assumed, allowing the calculation of the CSO risk with an analytical solution, as in Vezzaro and Grum [16].…”

Distinguishing high and low flow domains in urban drainage systems 2 days ahead using numerical weather prediction ensembles

“…detention basins and pumping stations implemented to improve the UDS management, e.g. (Vezzaro and Grum, 2014).…”

“…Radar extrapolation is e.g. often used to forecast flow (Rouault et al 2008;Vezzaro & Grum 2014). However, radar forecast are limited by their prediction horizon of 1 to 3 hours and by the need to dynamically calibrate the radar images to ground observations from rain gauges (Thorndahl and Rasmussen, 2012).…”

Application of CityDrain3 in Flood Simulation of Sponge Polders: A Case Study of Kunshan, China

“…Flooding is a natural disaster that causes damage to human lives, as well as the economy [3]. However, compared with plain catchments [4][5][6][7][8], less effort has been made in mitigating the flooding risks of polders [9][10][11]. Therefore, investigating measures to control polder flooding problems is of a significant value.…”