1. River Kokemäenjoki – Flood risk management & WFD
Brussels
Juha-Pekka Triipponen
Southwest Finland Regional Environment Centre

2. 8 River basin districs in Finland (WFD)
The Kokemäenjoki River is located in the southwest part of Finland and flows to the Baltic sea. The catchment area is about km2
8 River basin districs in Finland (WFD)

3. The hydrology of the Kokemäenjoki River
is characteristic by the high proportion of lakes (11 %) in the catchment area.
The length of the main Kokemäenjoki River is about 110 km. The river has been harnessed to generate hydropower which means water level regulation of the main lakes and the river flow.

4. Flood risk management in the Kokemäenjoki river basin district
The pilot project of the Flood Directive implementation in Finland
Preliminary flood risk assessment -> Potential flood risk areas:
The City of Pori ( inh.) at the mouth of the river
Flat agricultural area with some smaller municipalities and towns in central parts of the river
Thousands of rural houses and summer cottages in the lake district

5. Flood hazard maps and flood risk maps
– partly done already, new height model by National Land Survey will help in the lake district
Flood risk management plan
Prevention: Possibilities to regulate water levels of four lakes in upper catchments is the most important mean to prevent and mitigate flood damages in the lower river reach (an extensive run-off forecast system available)
-> some contradictions between flood risk management, hydro power generation and recreational use.
Climate change -> Need to change the regulation permits?
Protection: The needed flood protection measures
Preparedness: Co-operation between rescue authorities and water resources authorities -> operational action plan for floods in the city of Pori (2008)

6. Flood hazard map of Pori during a serious ice jam flood :
- Probability: 1/200 years buildings wet Damages to housing and industry: mill.€
Flood protection project in The City of Pori :
Dredging m3
New embankments 25 km

7. Ice jam in the centre of the City of Pori January 1975
Cumulative factors affecting to winter floods in the river Kokemäenjoki:
- High discharge at the same time with freezing due to the heavy rainfall in late autumn -> frazil jams
- Warming up and rainfall during winter -> frazil jams and ice break-up jams
The high sea level

8. Connection between the flood risk management and the WFD
- The run-off from the catchment areas to the Baltic sea during winter has increased -> significant part of the total nutrient loading (even 90 %) comes during warm and rainy winters because lack of vegetation on the fields (erosion & leaching)
What is the significance of the flood risk management for the nutrient loading?
the retention of the run-off on land areas -> relative significance and effect on the water quality

9. The Kokemäenjoki river – a heavily modified water body
The Harjavalta hydropower plant –the first barrier for the fish migration 40 km from the sea
Almost totally dammed up by 4 hydropower plants which carry out short-term water level regulation (permit)
Assessment of hydromorphological alterations  HMWB
Is good ecological potential already achieved?
- potential hydro-morphological mitigation measures are identified
- assessment how much it is possible to improve the current status with the combination of measures unfinished