Conditions
The winter canoe trips take place in the specific conditions. In the water, when the temperature falls down, below 0°C, the little icy crystals are being formed and float out on the water creating the so called – pancake ice. It looks like a spongy mass, through which you can easily canoe – it is just like paddling through the duckweed. Next drop in temperature forms the ice float. When the temperature falls below -10°C at night, the river complete freezes-up within few days. The process of water’s freezing begins from forming of the microscopically small ice needles, which opalesce in the sun when you pour the water into container. Before the entire water surface ices up, the water becomes thicker with the pancake ice creating the ice floats. In the same time the ground ice, in the shape of the grey-brownish sponges, gradually covers bottom and all the obstacles of the river. On the surface, the consistence of ice is different – it resembles the glass. By the riverbanks – especially in backwaters – the ice crust increases slowly but inexorably and can finally cover the whole surface of river. The ice float drifting by the river becomes thicker and starts to solidify. Finally, the ice blockades begin to form on the obstacles. The ice floats bind together forming a compact icy layer. The process of formation and accumulation of the ice blockade is very fast – the front part of the ice blockade gradually shifts upstream, as the water brings the new ice floats. The ice blockades often cause the local inundations – the water accumulates and floods the banks.