Fload and coastal protection

Flood Risk Management Guideline (2nd cycle): Lower Main area - models and calculations as a basis for flood hazard maps/flood risk maps (HWGK/HWRK)

In preparation for the creation of the flood hazard and flood risk maps within the framework of Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks (EC FRMD), the flood hazard areas were to be newly determined. Together with Aquasoli, Siegsdorf, Tractebel Hydroprojekt was awarded the contract for two lots. Tractebel Hydroprojekt focussed on the 'Lower Main' lot. This lot included 22 watercourse sections.

These were often narrow watercourses in residential areas, often with long culverted sections. Separate 2D models were created for these sections in order to adequately take their capacity into account and thus to be able to map the overflow discharge in the hydronumerical model.

The project workflow was carried out in delivery packages, each approved after a technical review by quality assurance and water management authorities. Delays in the area of surveying were made up for by flexible management on the part of the project management and by carrying out supplementary surveys ourselves.

Client: Bayerisches Landesamt für Umwelt

Processing period: 2017 – 2019

Main data:
Number of waters sections: 22
Length of surveyed watercourses: approx. 140 km
Length of modelled watercourses: approx. 170 km
Total modelled areas: approx. 6600 ha

Watercourse surveys incl. photo documentation
Coordination of terrestrial surveying of 19 bodies of water by several surveying offices (NAN)
Realisation of terrestrial survey for 2 water bodies
Data preparation for HIS'3D
Development of hydronumerical models for 21 watercourses (FSG, LASER_AS-2D, SMS)
Revision of the 2D model for one water body
Calibration and sensitivity analysis for the models (depending on the data situation)
Dike laying scenarios (1 model)
Hydronumerical calculations for 5 load cases each
Regular coordination with quality assurance, water management authorities and the LfU