Transfer Function Modelling of Urban Drainage Systems, and Potential Uses in Real-Time Control Applications

According to the present state-of-the-art, sewerage systems, sewage treatment plants and their subsequent improvements are often planned and designed as totally separate entities, each subject to a specific set of performance objectives. As a result, sewage treatment efficiency is subject to considerable variability, depending both on general hydrologic conditions in the urban watershed (wet versus dry periods), and on specific “instantaneous” operating conditions. It has been postulated that the integration of urban drainage and wastewater treatment design and operation could allow minimization of the harmful effects of discharges from treatment plants, overflows and surface water runoff. This “ideal condition” can be achieved through the introduction of so-called “real-time control” technology in sewerage collection and treatment operations. To be a feasible goal, this technology poses the demand for more powerful simulation models of either aspect of the system - or, ideally, of a unified sewer-and-treatment plant model - than most of those currently available. This paper examines the requirements of rainfall/runoff transformation and sewer flow models with respect to real-time control applications, and focuses on the methodology of stochastic, transfer function modelling, reporting application examples. Modalities and limitations of the extraction of information from the models thus derived are also analyzed.

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INTEGRAL CONTROL REQUIREMENTS FOR SEWERAGE SYSTEMS

Water Science & Technology ◽

10.2166/wst.1994.0014 ◽

1994 ◽

Vol 30 (1) ◽

pp. 131-138

Author(s):

Andrea G. Capodaglio

Keyword(s):

Real Time ◽

Sewage Treatment ◽

Operating Conditions ◽

Ideal Condition ◽

Real Time Control ◽

Combined Sewer Overflows ◽

Integral Control ◽

Time Control ◽

Combined Sewer ◽

Harmful Effects

Sewerage systems and sewage treatment plants are often planned, designed and operated as totally separate entities. As a result, sewage treatment efficiency is subject to considerable variability, depending both on general hydrologic conditions in the urban watershed (wet versus dry periods), and on specific “instantaneous” operating conditions. It has been postulated that the integration of design and operation in urban drainage and wastewater treatment could allow minimization of the harmful effects of discharges from treatment plants, combined sewer overflows and surface runoff. This “ideal condition” can be achieved through the introduction of so-called “Real-Time Control” technology in sewerage collection and treatment operations. This paper examines the requirements of a hypothetical integrated sewer flow and sewage treatment model, the mathematical tools used to design and operate Real-Time Control systems, and the issues emerging from an integration of the conveyance and disposal aspects of the sewerage cycle.

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Modelling large urban drainage systems in real time

Water Science & Technology ◽

10.2166/wst.1999.0185 ◽

1999 ◽

Vol 39 (4) ◽

pp. 21-28 ◽

Cited By ~ 5

Author(s):

I. D. Cluckie ◽

A. Lane ◽

J. Yuan

Keyword(s):

Transfer Function ◽

Real Time ◽

Urban Drainage ◽

Transfer Function Model ◽

Real Time Control ◽

Function Model ◽

Drainage Systems ◽

Time Control ◽

Time Flow ◽

Urban Drainage Systems

The interactions between rainfall and urban drainage systems (UDSs) are complex and must be considered as a whole in order to maximise control efficiency whilst at the same time achieving environmentally acceptable solutions. More rigorous standards, as a result of recent EU and UK legislation, are increasingly encouraging intervention in system management rather than more traditional passive procedures. To achieve these goals a global predictive real-time control (RTC) strategy is required, in which real-time flow prediction plays an important part in the provision of necessary first-hand information on system status in both current and predictive modes. This paper describes one such strategy, which differs from existing methods in the following ways: the novel way in which the UDS is represented; the algorithm used for model parameter identification; the strategies associated with the system output prediction; and the transfer function model used to represent the system. This transfer function model is a conceptually parameterised transfer function (CPTF) model, which by its nature falls into the category of lumped, dynamic, linear and conceptual although its structure takes the form of a non-conceptual transfer function model. The modelling approach is described as the RHINOS (Real-time urban Hydrological INfrastructure and Output modelling Strategy).

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Modifications of rainfall runoff and decision finding models for on-line simulation in real time control

Water Science & Technology ◽

10.2166/wst.1999.0477 ◽

1999 ◽

Vol 39 (9) ◽

pp. 201-207

Author(s):

Andreas Cassar ◽

Hans-Reinhard Verworn

Keyword(s):

Real Time ◽

Urban Drainage ◽

Rain Event ◽

Rainfall Runoff ◽

Real Time Control ◽

Design Storm ◽

Time Control ◽

Timing Data ◽

On Line ◽

Rainfall Runoff Model

Most of the existing rainfall runoff models for urban drainage systems have been designed for off-line calculations. With a design storm or a historical rain event and the model system the rainfall runoff processes are simulated, the faster the better. Since very recently, hydrodynamic models have been considered to be much too slow for real time applications. However, with the computing power of today - and even more so of tomorrow - very complex and detailed models may be run on-line and in real time. While the algorithms basically remain the same as for off-line simulations, problems concerning timing, data management and inter process communication have to be identified and solved. This paper describes the upgrading of the existing hydrodynamic rainfall runoff model HYSTEM/EXTRAN and the decision finding model INTL for real time performance, their implementation on a network of UNIX stations and the experiences from running them within an urban drainage real time control project. The main focus is not on what the models do but how they are put into action and made to run smoothly embedded in all the processes necessary in operational real time control.

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A novel approach to the real-time modelling of large urban drainage systems

Water Science & Technology ◽

10.2166/wst.1997.0638 ◽

1997 ◽

Vol 36 (8-9) ◽

pp. 19-24 ◽

Cited By ~ 6

Author(s):

Richard Norreys ◽

Ian Cluckie

Keyword(s):

Real Time ◽

Dynamic Models ◽

Drainage System ◽

Radar Data ◽

Urban Drainage ◽

Real Time Control ◽

Empirical Modelling ◽

Time Control ◽

Novel Approach ◽

Non Linear Systems

Conventional UDS models are mechanistic which though appropriate for design purposes are less well suited to real-time control because they are slow running, difficult to calibrate, difficult to re-calibrate in real time and have trouble handling noisy data. At Salford University a novel hybrid of dynamic and empirical modelling has been developed, to combine the speed of the empirical model with the ability to simulate complex and non-linear systems of the mechanistic/dynamic models. This paper details the ‘knowledge acquisition module’ software and how it has been applied to construct a model of a large urban drainage system. The paper goes on to detail how the model has been linked with real-time radar data inputs from the MARS c-band radar.

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