The Preliminary Flood Risk Assessment in Tana River Basin
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In cooperation with: The preliminary flood risk assessment in Tana River basin Table of contents 1 Background .................................................................................................................................3 2 Description of the river basin ....................................................................................................5 2.1 Hydrology .................................................................................................................................6 2.2 Settled areas and land use .................................................................................................... 11 2.3 Planning ................................................................................................................................. 13 2.4 Protected areas and cultural heritage ................................................................................... 14 2.5 Flood protection ..................................................................................................................... 16 3 Historical flood information ................................................................................................... 18 3.1 Observed floods .................................................................................................................... 18 3.2 Ice jams and floods................................................................................................................ 19 3.3 An estimation of damages caused by floods in past nowadays ............................................ 21 4 Floods and flood risks in the future ...................................................................................... 22 4.1 Effect of climate change ........................................................................................................ 22 4.2 Effects of other long-term developments on flood risks ........................................................ 23 5 Using GIS-data in flood risk area estimation ........................................................................ 25 5.1 Finland ................................................................................................................................... 25 5.2 Norway .................................................................................................................................. 26 6 Identifying flood risk areas ..................................................................................................... 27 6.1 Empirical knowledge and earlier reports ............................................................................... 27 6.2 Flood risk to human health and security................................................................................ 27 6.3 Flood risk to essential services for community ...................................................................... 28 6.4 Flood risk to environment and cultural heritage .................................................................... 29 6.5 The flood risk caused by water construction structures ........................................................ 30 7 Suggestions for the significant flood risk areas .................................................................. 31 8 Sources .................................................................................................................................... 33 9 Annexes .................................................................................................................................... 35 Annex 1. Hydrological information Annex 2. Summary, In Inari Sámi Annex 3. Summary, In Skolt Sámi Annex 4. Summary, In North Sámi Preliminary Flood Risk Assessment in Tana River Basin 2 1 Background Finnish Act for flood risk management (620/2010) and decree on flood risk management (659/2010) came into force in summer 2010. The purpose of the law is to decrease flood risks, to prevent and reduce harmful consequences caused by floods and promote the preparation for floods. Another pur- pose is to reconcile the flood risk management and other management of the river basin taking the sustainable use of water resources and the needs for environmental protection into account. Besides means of water management attention is especially paid to land use planning, building guidance and rescue services. The goal of flood risk management is to reduce harmful consequences to human health and safety. By the Act and Decree EU's Directive on Floods is implemented in Finland. The flood risk management consists of preliminary flood risk assessment, nomination of possible sig- nificant flood risk areas, preparation of flood hazard and flood risk maps and also preparation of flood risk management plans. In preliminary flood risk assessment (deadline 22.12.2011) areas, that may suffer major damages from flooding, are found out. To those possible significant flood risk areas flood hazard maps and flood risk maps (deadline 22.12.2013) and flood risk management plans (deadline 22.12.2015) are prepared. In flood hazard maps the extent and the water depth of flood are presented by using certain flood frequency. Flood risk map describes possible damages caused by a flood, those damages are for example the amount of inhabitants that suffer from consequences and sites that are harmful for environment. In flood risk management plans the actions that reduce the flood risks are presented. Concerning river floods the flood risk management plans are prepared for river basins where exist one or more possibly significant flood risk area. The preliminary flood risk assessment creates an important basis for flood risk management. In Finland the preliminary flood risk assessment of river basins and shore areas are taken care by Cen- tres for Economic Development, Transport and the Environment (ELY-centre). Municipalities are re- sponsible for assessment of flood risks caused by storm water. According to the Act, the preliminary flood risk assessment is done by using available information about occurred floods and development of climate and hydrology; and also the climate change in future should be taken into account. In as- sessment information about occurred floods and possible floods in future and their harmful damages are gathered. The preliminary flood risk assessments are based on information that already exist, major new researches aren't done. The preliminary flood risk assessment is done by river basins and the assessment of flood risk from sea flooding is done by ELY-centres' operating regions. The ministry of agriculture and forestry accepts the significant flood risk areas in river basins and shore area by the proposal from ELY-centre. The goal of the preliminary flood risk assessment is in Finland to find the significant flood risk areas defined in the Finnish Act for flood risk management (620/2010). When estimating the significance of the flood risk area next mentioned from general viewpoint adverse possible consequences caused by flood are taken into account: 1) adverse consequence to human health or security 2) long-term interruption of essential services like water or energy distribution, telecommunica- tions, road traffic or other related services 3) long-term interruption of economical actions that secures the essential services of commu- nity 4) long-term or extensive adverse consequence to environment 5) irreparable adverse consequence to cultural heritage Norway is not included in EU countries, but it belongs to EEA (European Economic Area) via EFTA (European Free Trade Association). EU's Directive on Floods will be implemented in Norway by same timetable as EU countries. Ministry of Petroleum and Energy (MPE) is the state authority concerning Preliminary Flood Risk Assessment in Tana River Basin 3 EU's Directive on Floods. The Norwegian Water Resources and Energy Directorate (NVE) is an agency of the Ministry of Petroleum and Energy, NVE is responsible for the management of energy and water resources in mainland Norway (Ministry of petroleum and energy 2010). NVE will be also responsible for implementing the EU's directive on Floods. NVE and MPE are currently figuring out how to implement the Directive in Norway. Preliminary Flood Risk Assessment in Tana River Basin 4 2 Description of the river basin The Tana River basin is situated in the northern part of Lapland province in Finland and in the middle part of Finnmark province in Norway. In Finland Tana river basin is part of the Tana-Neiden-Pasvik river basin district and in Norway a part of Finnmark river basin district (Vannregion Finnmark). The Finland's area is divided to the areas of two municipalities, Inari and Utsjoki. In Norway the watershed is divided to the areas of three municipalities, Koutokeino, Karasjok and Tana. The Tana River forms together with its head waters 288 km national frontier between Finland and Norway. The river flows from south to north and the actual River Tana begins from the connection point of the River Inarijoki and the River Karasjohka downstream the Karigasniemi village. The river flows to the Tana fiord and the last 50 km it flows in Norway. Tana watershed (Finland no 68 and Norway no 234) has a total area of 16 389 km2, of which 31 % is in Finland and 69 % in Norway. The lake percentage of the watershed is 3,1. Between Karigasniemi and the national frontier there is approximately 109 meters fall and from the national frontier to the Arctic Ocean the fall is 15 meters. The river is one of the Europe's most signifi- cant rivers of migratory fishes.