Invigorating rain

Rain after a period of drought is like a breath of new life for the dry earth. Plants recover and the whole world looks brighter. The rain also replenishes lakes and rivers as well as groundwater reserves.

The yearly rainfall amount in Finland is around 600 millimetres, equalling an accumulation of 60 centimetres of water, or well over your knees, in a container with a flat bottom and sides. To factor in snow, its volume is converted into water for this calculation.

Rather than being the same in all parts of the country, the annual rainfall amounts are usually the lowest in Northern Lapland and highest in Southwest and Eastern Finland. Precipitation also varies from year to year, and this year’s rainfall may be twice the last year’s amount in the same area.

Precipitation affects the flow rates of rivers and water levels in lakes, but with a delay as the ground and especially peatlands absorb water like sponges. In a large catchment, it takes longer for the rainwater to reach a lake, whereas the situation is reversed when the rain stops: water keeps trickling into the rivers and lakes for a long while.

After a dry period, it may likewise take months of heavy rain before groundwater reserves start being effectively replenished.

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