Under our towns and cities lie complex networks of pipes and other facilities that remove the waste water from our homes, industries and rainfall and transfer it to treatment centres and discharge points. Over time the performance of these networks can become unsatisfactory. This may be because of their physical deterioration, or because of a change in demand due to industry, housing or rainfall. Under these circumstances the network owner must determine the best strategy for revising or developing the network to recover satisfactory performance. Planning this type of intervention is a very sophisticated process since the costs are potentially very high, and the disruption to communities can be severe. In common with most industries, the hydraulic engineering community has developed sophisticated modelling techniques upon which they base their analysis of the effects of any proposed change. The starting point for the modelling process is a representation of the existing network based on historical and survey data. Many of the parameters of this baseline representation are known only to a limited precision, so some tuning or "verification" is required at the beginning of the analysis process. During verification, the performance of the simulated network is tuned to match physical results from flow monitors obtained during dry weather and rainstorms. This verification phase can take a substantial period of time as even a simple network may incorporate over one thousand pipes and land sub-regions, along with all the attendant infrastructure of pumps, storage tanks and so forth.
In this paper we demonstrate the use of modeFRONTIER to improve the time taken to verify these sewer models. To assist in the verification process it was necessary to link modeFRONTIER to Infoworks, for which an interface was developed. This enabled modeFRONTIER to control Infoworks through a custom-developed spreadsheet application. Using this interface, trial verifications of real networks were explored for both dry days (where the flow is undisturbed by rainfall) and storms, where the flow is dominated by the influx of rainwater.
Methods are included in the interface for coping with defective physical test data and for adjusting the variables selected for adjustment. The user is able to inspect the progress of the developing model using the normal Infoworks capabilities as well as through modeFRONTIER. The paper describes the background, capabilities and use of this interface.
An example verification is presented, beginning with dry day data undisturbed by rainfall and matching the night time and peak flows across the network. This phase of the verification is developed to cover storm performance where the flow data is dominated by an influx of rainfall water - in this case multiple storms are analysed simultaneously to match the industry standard target parameters of peak flow, pipe water depth and total daily flow. The quality of the resulting verified networks is discussed, with indications of the methods by which the process may be applied in practice. Preliminary analysis suggests that the time required for verification can be substantially reduced, and measures are given of the potential savings in time and therefore cost of this type of activity.
Beyond the work described above, the paper discusses future plans for the interface, further developing the capabilities in the area of verification and extending them to cover the optimisation of proposed design changes once verification is completed.
The work was undertaken by Grontmij and EnginSoft UK Ltd. Grontmij are one of the leading hydraulic and civil engineering consultancies in the UK. Invaluable support was provided by Wallingford Software, the developers of the Infoworks CS sewer simulation software, upon which the simulations were based. United Utilities also played a significant role in providing a real-world test case for the investigation. |
