Modelling run-off during heavy stormwater events

SUDPLAN Newsletter 1 (December 2010): The City of Wuppertal has decided to use the software GeoCPM by tandler.com GmbH / Pecher AG as the model component for the SUDPLAN Wuppertal pilot. In parallel to this decision the modelling of the surface run-off during heavy stormwater events has been introduced into the continual planning process of Wuppertal’s sewer system, called ‘Generalentwässerungsplanung‘ (General Drainage Strategy). First results of this new modelling approach can be shown.

GeoCPM implements a hydrodynamic surface run-off model. It is a component for ++SYSTEMS, a GIS with subject-specific modules for all aspects of the sewerage domain. Therefore it can easily be combined with the module DYNA, that is already in use for the weak-point analysis of the sewage systems.

Calculate the stormwater surface run-off

In the SUDPLAN Wuppertal pilot GeoCPM will be used to calculate the stormwater surface run-off in model runs defined with the SUDPLAN Scenario Management System (SMS). The most complex input parameter for such a model run - besides the simulated precipitation data - is an optimised high-resolution digital elevation model (DEM), the so-called ‘calculation model’.

The labour-intensive step in creating a calculation model is to define all the relevant man-made break lines like the exterior walls of buildings or road kerbs. So far calculation models have been set up for the catchment areas of the two streams ’Varresbeck’ and ’Lüntenbeck’. First results of the modelling work are available now.

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Flooded areas calculated with GeoCPM and DYNA for the stream ’Lüntenbeck ’ (Pecher AG).

Execution of model runs

But what is the impact of these latest developments on the SUDPLAN Wuppertal pilot? It means that we are ready to tackle the use cases that are in the heart of the Wuppertal pilot, namely the definition and execution of model runs concerning stormwater flooding.
 
Both the necessary software components and the required data are on hand by now. Thus the next major activity in the Wuppertal pilot development will be a workshop that brings together the SUDPLAN partners who are in charge of the implementation of the SMS and the model component experts.

The main goal of this event will be the development of a clear specification for the communication between the SUDPLAN SMS and GeoCPM.