Lecture 7+8 (MIKE URBAN modelling – Tommerup exercise) Flashcards
What does 1D modelling mean in MIKE URBAN in terms of velocity?
The velocity is calculated in one direction.
What does sewer separation mean?
That you separate an old, underscaled combined network into a two stringed network –> Waste water and stormwater in separate systems.
What is the function of a stormwater system?
It delays and clean the water to protect the recipient.
What is an optimal stormwater system?
No flooding at a 5 year CDS rain event and no extra volume in pipes.
Why is it important to have a well descripted MIKE URBAN model?
o Calculate optimal pipe dimensions
o Efficient tool if there afterwards are changes in the project:
- What happens if we make this change? Is it possible? Etc.
What is a well descripted MIKE URBAN model?
o Well defined catchments
o Imperiousness of catchments
o Linking catchments to the right manhole
o Measured data for existing elements: manholes, pipes etc.
Why do we need to decrease overflow to streams/lakes?
- To secure good environmental conditions –> EU Water Frame Directive
Which data are needed for creating a good MIKE URBAN model?
- Input from the utility’s database of their sewer system: manholes, outlets, pipes, pumps, weirs, basins, regulators
o Estimate missing information - Input from the utility’s old drawings of basins, structures, pumps, ect.
- Catchments: size and imperiousness
o Input from maps with information of buildings, roads, parking lots, land register (cadastral map)
o Or maximum allowed imperiousness (determined by the municipality) - Waste water input from measured water consumption
- Analyse system with 1 year rain event: dead ends? Errors?
- Calibrate model: Compare measured data with calculated data – agreement?
What can MIKE URBAN model be used for?
- Analyse the sewer network of the city
o Where are the large “high way” pipes?
o “Bottlenecks”?
o Flooding (blue spots)? - Input to the sewer renovation plan of the utility
o How to prioritise the work that needs to be done.
Describe the climate adaptation case in Tommerup.
The task of the project:
o Stream is flowing under terrain in pipes through the village
Needs to fulfil the Water Frame Directive (good environmental condition)
o The utility has to secure the stormwater system to the service demand
No flooding at a 5 year rain event (the village has a separated sewer system)
o The municipality has to reduce the risk of flooding under cloudburst.
o Create common solutions on terrain
Drainage function
Increase nature elements
Recreational values
What was the solutions for the climate adaptation case in Tommerup?
o Reopening the stream
o Detention of water in the upstream stormwater system: Basins, ditches, soakaways
Bigger pipes as last solutions
o Redirection of the stormwater – cut off from main system to separate outlet
o More stormwater outlets to the stream with a low discharge than few outlets with high discharge – reduce the risk of erosion
o Stormwater basins before discharge to the stream
Detention and cleaning of stormwater
What was assignment 7 about (Tommerup exercise)?
We got the model used for Tommerup in the climate adaptation case and then we needed to edit the model with solutions, that could prevent flooding at a 5-year rain event by using elements on terrain.
These elements could be:
o Insert basins with regulation – detention water in the upstream system
o Redirect the stormwater - cut off from main system to separate outlet (new pipes necessary)
o Bigger pipes as last solution
o Basin before outlet to stream.
How did our solution looks like for the assignment?
We made a simulation on the existing model to see where the floodings would be placed. Then we tried to incorporate a basin in between some of the pipes and then drain the water to a near stream.
