Flood Risk Management Plan A National Pilot from the River Kokemäenjoki

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1 Flood Risk Management Plan A National Pilot from the River Kokemäenjoki 26-27th January 2010, Maastricht Olli-Matti Verta & Juha-Pekka Triipponen Southwest Finland Centre for Economic Development, Transport and the Environment

2 The River Kokemäenjoki Fourth largest river catchment in Finland, approx km 2 It flows to the Baltic Sea, avg. flow 245 m 3 /s High proportion of lakes in the catchment area, 11 % Most of the largest lakes are regulated There are eleven significant water power plants The ecological state is good in most of the lakes and mainly satisfactory in the main river

3 Pori January 1975 Initial data for FRMP Existing data quite adequate First historic data about floods and damages from the year 1899 Hydrological monitoring since the year 1863 Different open water, frazil and ice jam floods hydraulically modeled New elevation model (laser scanned) 2009, elevation accuracy at least 15 cm Flood hazard and risk maps partly done Pori January 1982 Pori January 2005 viraston nimi, tekijän nimi ja osasto

4 Collaboration The preparation of the pilot FRMP started in the year 2007 and will be finalized during 2010 Steering group of the FRMP 16 organization persons 6 meetings so far Working groups (experts and steering group members)

5 The Preliminary Flood Risk Assessment Done mainly according to the historic data, e.g. January 1975 ice jam flood In addition a GIS-based preliminary flood risk assessment is being carried out At least two significant flood risk areas: Pori January The City of Pori ( inh.) at the delta of the river 2. Flat agriculture area with some smaller municipalities and towns in the central part of the main river?? The large lake district with thousands of rural homes and summer cottages still in consideration viraston nimi, tekijän nimi ja osasto

6 Flood Hazard and Risk Maps and Damage estimations Flood hazard and risk maps for several water level and flow probabilities: 2 % yearly probability (=once in fifty years repetitiveness) 1 % (1/100) 0,4 % (1/250) Several different sea level, frazil and ice jams and flow combinations for the City of Pori The City of Pori Partly still in process buildings damaged people exposed - Direct damages to buildings and industry: mill

7 Climate Change Several different climate change scenarios used Modeled periods , , Snow cover time and amount of snow will decrease Spring floods will decrease Late autumn and winter rainfall will increase Autumn and winter floods will increase Frazil and ice jam risk will increase

8 Flood Risk Management Objectives Overall objectives: Avoid loss of human lives Diminish economic, ecologic and social damage Enhance preparedness for operative flood management Increase public awareness and preparedness Separate objectives for each substantial flood risk area 1. The City of Pori Objective is to prepare for serious frazil and ice jam flood, estimated probability 0,5 1 % This also prevents serious damages in 0,4 % probability open water flood 2. Central part of the main river Objective is to prepare for 1 % probability open water flood Single important objects such as large piggeries and other pounds and residential buildings are prepared for 1. 0,4 % probability open water flood

9 Flood Risk Management Measures 90

10 Conclusions The main challenges: Adaptation to the climate change both flood prevention measures, specially adaptive lake regulations, and substantial flood protection measures are needed Adaptive lake regulations requires Changes to legitimate regulation permits Changes to current water act more coercive means for authorities to ensure regulation that minimizes overall flood damages The reconciliation of flood risk management and other interests (e.g. hydropower, recreational use, nature conservation) The pros and cons are not necessarily directed to the same area not easy to get local endorsement Findings from the cooperation: Readiness for cooperation is widespread Need for explicit leader in operational river basin flood management current system shifts from water authority to rescue authority and by regions Some political intentions also involved in the process makes the decision making more difficult Collaboration between authorities, municipalities and hydropower companies is the key element to successful flood risk management