Uitgangspunten falen keringen template
This page describes the assumptions that are used as input for the falen keringen template and manual.
Introduction
The manual describes the steps that need to be taken to quickly and in an efficient manner create a new Tygron Platform project with a flooding scenario. The following settings/presence of data influences the accuracy and outcome of the calculation (in order of importance):
- The size of the breach
- The upstream (?)water level of the breach
- Capacity of water body upstream(?) breach (how quickly does the water level lower as a result of the breach?)
- Grid size
- Culverts in (the to be) inundated area
- Initial water level in (the to be) inundated area
Below the assumptions about these settings are explained in more detail.
Breach size
A breach is a modification to the terrain height, with an optional in- or outflow of water for the hydrological model. With breach size, the placement of the active breach area in the 3D model is meant. This breach area can be imported or manually drawn. In the falen keringen manual, the breach area is drawn in he 3D world.
Breach water level area
In the Tygron Platform there are two methods of determining the amount of water that will flow through the breach: with an internal area or an external area. For this falen keringen template, the external area is used, since it is easier to determine in the wizard the parameters for the external area and it is not necessary to import water depth data of the main system to calculate a correct capacity of the water body. On the other hand, by using an external area, it is not possible to see the water in the main system lower to a different water level.
Breach capacity
Grid size
The grid cell size influences the accuracy and the calculation time of the project. Since is assumed that projects are rather larger (magnitude: .. x .. km or larger), the grid cell size is set to 2 x 2m. Also, the calculation preference is set to normal. (Note: outcome of tests should be added.)
Culverts
By default in the Tygron Platform in the Netherlands and if available, culverts are imported from the IMWA dataset. Due to the unknown culvert diameter of these hydrological constructions, the default diameter of 1m is used. Through tests, this default diameter proved to show differences in Flooding results, therefore in the manual, culverts with their known diameter need to be imported. Other hydrological constructions such as weirs and pumps proved to be insignificant for this use case.