University of Twente Student Theses


Validity assessment of D-Hydro Urban : comparing D-Hydro with Infoworks ICM in a Beverwijk sewer modelling study.

Besseling, L.S. (2020) Validity assessment of D-Hydro Urban : comparing D-Hydro with Infoworks ICM in a Beverwijk sewer modelling study.

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Abstract:The Dutch institute for water research Deltares is developing a new software package, D-Hydro, to replace their older water modelling software. D-Hydro will face the widely used Infoworks ICM as its main competitor on the market. The new software gained the interest of Wareco, an engineering firm specializing in the urban water system and providing service for the design and evaluation of sewer systems, including waste water, surface water runoff and groundwater control. This modelling study is aimed at generating knowledge on the performance of D-Hydro in comparison to Infoworks ICM, both for the validation effort of D-Hydro by Deltares, and for gaining insight in the potential and applicability of the software for Wareco. The case study for this research is the municipality of Beverwijk, the Netherlands. The municipality is located on sloping terrain, making it an interesting place to see how the model behaves in cases where flow across the surface level is relevant. In the research project, a model of the urban water system of Beverwijk was thus made in both Infoworks and D-Hydro. The two main components of the models were the sewer system and the surface level. The sewer system model contains manholes that allow water to enter the sewer system and leave the sewer system in case of sewer system overload; piping for transporting the water to the wastewater treatment plant; pumps to move the water into the treatment plant and out of the model; and overflows to spill the water into the surface water system. However, an actual surface water system model was not included due to delayed data and time restrictions. Therefore, the water is deleted once over an overflow. Of the sewer system, only parts that carry rainfall are considered. The surface level model is modelled on a 3x3 meter grid for D-Hydro, and an unstructured mesh of polygons of about 8.75-9.25 m2 each for Infoworks. The cells of the surface level are given a height that was obtained from a DSM map of the Netherlands, as well as a set of values that reflect properties of their type of surface. These include roughness and infiltration, which are important for the calculation of water flow across the surface. The surface level model and the sewer system model are linked at the manholes. Water can thus enter the sewer system if it lands on the grid cell of a manhole, or it can leave the sewer system and begin flowing on the surface from that same grid cell. Two rainfall events were used to conduct tests in this modelling study. They were retrieved from the Dutch guidelines for sewer system testing, and are also listed in the ambitions of the municipality of Beverwijk. The first is known in the Netherlands as bui09, in which 29.4 mm falls in an hour, with a peak at the beginning of the event. The second is a stress test for climate change: a constant intensity rainfall event of 60 mm in an hour. The results of both modelled rainfall events indicated that D-Hydro predicts a smaller water depth of street flooding, and less water in the 1D sewer system than Infoworks. This seemed impossible, unless D-Hydro had processed less water than Infoworks. Eventually, evaluation of the results of the model runs led to the conclusion that D-Hydro contains a bug that caused it to lower the amount of precipitation on roofing, while a modelling error in Infoworks caused a doubling of this rainfall . A workaround for the bug was set up and new model runs were conducted, but not enough time was left to thoroughly investigate the improved results. Therefore, this research cannot definitively conclude on where differences between the models originate, and what causes them. However, it can conclude that the workflow of D-Hydro, being in beta-testing, allowed for most elements of the water system to be successfully implemented, although doing so was more challenging than in Infoworks. Still, the research has been a useful experience for both Wareco and Deltares, the former gaining insight in the workflow of D-Hydro and the latter obtaining a lot of information on the performance and capabilities of their software.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Programme:Civil Engineering BSc (56952)
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