Miljøprojekt Nr. 1188 – Klimatilpasning af afløbssystemer og metodeafprøvning. Workshop som arbejdsmetode.

Klimatilpasning af afløbssystemer og metodeafprøvning. Workshop som arbejdsmetode.

Summary and conclusions

Introduction and scope

Climate changes are expected to cause significant changes in the water cycle in Denmark. In urban areas, some of the consequences will be increased sea water level and more frequent and heavy extreme rainfall. This project suggests an approach for analysing the consequences of these changes at the municipal government level.

The project has focused on creating a joint municipal approach to the problems caused by climate changes and finding the most adequate adaptation to the expected climate changes.

Method

Part of the project has been to test the need for data material to screen the consequences of the increased sea water level and extreme rainfall. In this connection, a two-day workshop was arranged with participation of officials from Aalborg and Roskilde municipalities and external experts.

The steps needed for a successful workshop are:

Determination of objective of the workshop
Preparation of basic data
Realisation of the workshop
Processing of results from the workshop

This report deals with the two first bullets, i.e. objective and basic data.

Concerning extreme rain, the objective of the workshop could be:

Review of scope
Focus on vulnerable areas
Determination of future service level
Key figures on damage compared to key figures on damage improvement
Specific solutions
Need for emergency plans in connection with extreme rain

In connection with extreme water level the objective could be:

Identification of affected areas, recognition of scope. Do we have a problem?
Are there particularly vital places/buildings, which must be protected prior other areas
Scope of damage
Costs related to damage
Possible solutions
Costs related to solutions

For the workshop, it is necessary to have thorough data material showing the consequences for the individual municipalities. This might include maps showing:

The extent of surcharge to terrain from sewage systems during heavy rain
Flow movement on terrain and local depressions where water will be stored temporarily
Areas located under a future critical level in connection with extreme water level
Map with indication of local experience, e.g. known problems and registered damage

Conclusions and future work

The method described in this report has been tested in two municipalities, i.e. Roskilde and Aalborg. Based on these two cases, the following is concluded:

The suggested method is suitable for placing focus on the need for climate adaptation across the municipality
The described basis for decision on extreme rain and sea water level was sufficient and suitable in relation to risk screening which was the objective of this study
A similar basis for decision could be necessary for other types of climate changes causing damage in cities. The municipal officials emphasized flooding caused by high groundwater level and heavy runoff through streams

At the time of writing, the results from the workshop are being further processed in the municipalities involved. In Aalborg, the results are incorporated into specific civil works projects, while the experience in Roskilde is used to bring a systematic cooperation across the municipal administration into focus in connection with preparation of a joint municipal strategy for climate adaptation. Furthermore, Roskilde municipality is working on a further improvement of the data material.