Floods and the flood protection in Rovaniemi and Kittilä

• The river Kemijoki •The longest river of Finland, 550 km

•The Kemijoki’s drainage basin is the Finland’s second biggest, 50 000 km²

•Hydroelectric power production was started in 1948, there are found 8 hydroelectric power-plants in river Kemijoki

• The river Ounasjoki • The longest tributary of the river Kemijoki • The Finland’s longest river which flow free, length is 298 km

•The Ounasjoki drainage basin is almost 14 000 km² and it cover 27 % of the Kemijoki’s drainage basin

Floods

• The biggest floods arise after snow melting in spring• When discharges together in Kemijoki and Ounasjoki are

about 4 000 m³/s, Rovaniemi begins to suffer from flooding.

• When discharge in Ounasjoki is about 850 m³/s, Kittilä begins to have flood damages

• Risks for flooding are also caused by ice jams

• The lastest big flood was • in Rovaniemi in 1993

• in Kittilä in 2005

Saarenkylä in Rovaniemi in year 1973

Saarenkylä in Rovaniemi in year 1973

Kittilä in 2005

Kittilä in 2005

Kittilä in 2005

Flood area in Kittilä in year 2005 modeling on the air map

-Blue describes the flood area-Red line is the border of an area, where an accurate digital elevation model is available

The flood hazard map in RovaniemiHQ 1/100 year, discharge 5 102 m³/s

Saarenkylä’s flood area once in 100 years

Climate change and floods

• Climate change will not impact very much on flooding • The risks for flooding are same than today

• Floods in spring will first increase, but when climate become warmer floods can little decrease

• Floods will little increase in summer and autumn

The flood protection alternatives

• The flood embankments– Easy to carry out and good

choice in some places– Hide beautiful river view– Not be suitable in places

where is fine-grained land

• The flood embankments are planned in Kittilä

• Rovaniemi has made the preliminary plans of the flood embankments

The flood embankments in Kittilä

The preliminary plans of the flood embankments in Saarenkylä

The flood embankment

The flood protection alternatives•Dredging

•Improves flowing in river•Difficult and expensive to carry out•Need more investigations and many permissions before it can be carried out in Kittilä or Rovaniemi

The flood protection alternatives

• Reservoir for flood protection– Reservoir is big pool, where snowmelt water is stored if big

flood threatens– Reservoir is good choice but it is very expensive and slowly to

carry out– Two reservoir have as preliminary been planned for above

municipality of Kittilä

• The law of the river Ounasjoki and natural protection areas cause legal troubles if we want to carry out dredging or reservoir

Flood protection alternatives

• Change the regulation’s orders• That means: the old regulation’s orders are updated and

the capacity of the lake Kemijärvi is raised (Kemijärvi is situated about 100 km to the north from Rovaniemi, upriver to Kemijoki)

• Simultaneous flood peaks of the rivers Ounasjoki and Kemijoki in Rovaniemi can be avoided by the regulation of Kemijoki

• Impacts of the regulations are useful in the flood protection, but regulations help only few days because of the small capacity of Kemijärvi

Other alternatives on the flood protection

• Temporary flood protection structures• Sandbag walls and other structures• Structure’s material has to be fast built, easy to carry to

flood area and withstand water pressure

• Developing flood protection communication and co-operation between all actors

• The combination of different alternatives could be the best choice in flood protection

The temporary flood embankment in Kittilä

The sandbag wall in Kittilä

Thank you for your attention!