potential flow paths in heavy rain
Description
A unidirectional D8 algorithm was used for the purely topographical determination of potential flow paths in the terrain. This determines the drainage direction of each grid cell of a digital terrain model from 8 possible directions. The approach can be imagined as follows: From each point of the terrain surface, you let a ball roll out one after the other and record the path taken. Where the paths of many spheres overlap, it is more likely that concentrated surface drainage will occur in heavy rain. If a ball reaches a sink from which it is not possible to “roll on”, the terrain is filled at this point in the model so that the ball can “roll out”. The investigation approach assumes that the replenished area is potentially filled with water in the heavy rainfall, as the drainage is also hindered and therefore likely to accumulate water. The area is identified as a terrain sink. The determined flow paths are blended with the water areas (from the ALKIS dataset Actual Use). The methodology used is independent of loads. It is not based on a defined heavy rain event with a certain duration or intensity, so the indications cannot be assigned to any particular annuality or probability of occurrence. In terms of potential flow paths, the methodology does not provide information on expected flow depths (water level), flow velocity and spatial expansion of a flood area (e.g. width of the flow path). The potential flow paths are classified according to the size of their connected catchment area. In a larger catchment area, it is assumed that the likelihood of surface runoff is also greater. In general, the indications of potential flow paths at settlement edges and on open areas should be considered more reliable. Within settlements, reliability can decrease, as the flow paths are influenced by numerous small structures (edge stones, walls parked vehicles, etc.), which, however, cannot be mapped in the digital terrain model. Notes from this layer must be verified locally with local knowledge. In principle, it cannot be ruled out that floods occur outside the areas and indications shown.
For more information see FAQ document - https://s.bayern.de/StarkregenFAQ
Resources
| Name |
Format |
Description |
Link |
Tags
- überschwemmungsgefahr
- oberflächenabfluss
- dauerregen
- gdiby
- umweltatlas
- naturgefahr
- inspireidentifiziert
- hios
- bayern
- fließwege
- sturzflut
- cc-by-sa
- starkregen
- überschwemmungsgefährdet