NEWS

Summary of the 10th Flood Risk Symposium of the “German Association for Water, Waste Water and Waste”

Feb 22, 2019 | News & Views, What's New

Written for ASFPM by Dr. Klaus
Piroth, CDM Smith, Conference Technical Chair

On Nov. 29, the 10th
Flood Risk Symposium of the “German
Association for Water, Waste Water and Waste” was held in Magdeburg, the
capital of Saxony-Anhalt, Germany. The symposium was established as one of the
outcomes of the research project RIMAX (Risk Management of Extreme Floods),
initiated after the 2002 floods in Germany and elsewhere in Europe and was
sponsored by the German Federal Research ministry. The DWA established a
working group for transferring the results of the RIMAX-Projects into practice.
This working group recommended a yearly Flood Risk Symposium where results and
progresses in flood risk management in Germany are presented and discussed.

Regionality is one of the keywords to
describe the German water management situation. This refers to the hydrologic
and hydrodynamic situation as well as to the structure of the water authorities
– in Germany the responsibility for water legislation, and execution, is up to
the states and not the federal government. So the Flood Risk Symposium is
rotated among various regions with a focus on the specific regional problems
being the subject of presentations.

The River Elbe, which runs through
Magdeburg, is the dominant river in the state of Saxony-Anhalt. There are big
former flood areas and meadows that were partly “reactivated” by several dike
breaks during the 2013 floods.

The program had four parts:

In Part 1 the
actual state of the implementation of the EU Floods Directive in Saxony-Anhalt
was discussed. In
Saxony-Anhalt, flood risk was evaluated along 67 rivers with a total length of
about 1,900 km (1,180 mi). The total flooded area is about 3,500 km2
(734 mi2) for a 200-year flood. Saxony-Anhalt follows the “room for the rivers” concept.
Former flooding areas are now planned to be reactivated by relocation of dikes
and the construction of polders (pastures or farms). In the renovation or
reconstruction of flood protection measures the state invested since 2002 more
than 940 Million Euros (US$1.067B). More than 868 km (539 mi) of dikes have
been renovated or constructed completely new and about 1.500 ha (3.7 ac) of
retention areas has been activated. Along the river Elbe, 266 Million m3
(9394 ft3) effective storage will be activated by means of nine
polders that are now being planned and constructed. In addition to the
Technical Flood Protection Measures, the flood warning model for the river Elbe
is being permanently improved. Another important topic is the risk management
of flash floods caused by heavy rainfall and the adoption of flood risks maps
for smartphones use. These risks can occur statewide and is therefore a real
challenge.

Part 2 was
dedicated to risk communication issues.
An overview of concepts and experiences with public risk communication of flood
protection measures were provided. This issue is becoming more important. In
many cases, professional moderators or communicators are being involved to support
technical staff.

Part 3 addressed
the opportunities provided by space and regional planning tools. German federal law directs the states to require
more strict rules for all buildings in areas at risk, in particular at the 100-year-flood
recurrence.

Part 4 gave an
impressive insight to the possibilities of dike/dam breach modelling and the online prediction of the flooding due to
the breach. These calculations help the responsible committees
(“Katastrophenstab”) to decide on evacuations and give information about which
areas can still be accessed. The use of drone technology for airborne surveys
was discussed to improve the online prediction of flooding by comparing
observations with calculations.

In summary, the Flood
Risk Conference gave an excellent overview on the ongoing work along the Flood
Directive. The next Flood Risk Conference will be held in Cologne in November
2019.

Below: Central Park in
Magdeburg, Germany flooded by the River Elbe in June 2013 (The Irish
Independent).

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