Monthly hydrological report in February 2000
Accumulation of snow continued during February particularly in eastern and northern Finland, where the snow cover was already heavy. In these regions the snow cover resembled that of the record-breaking winters of 1997 and 1998. In the south and west
the snow was compressed and partially melted. Water volumes in the watercourses were rather abundant for the time of year, with the exception of the largest lakes and groundwater formations of eastern Finland. Ice covers were weaker than normal.
Precipitation during February, in the form of rain and snow, was considerably above the seasonal mean in many areas. The recorded precipitation was generally between 30 and 60 mm, i.e. the measured precipitation figures were typically 1.5-2-fold
compared with the long-term February mean. Particularly heavy precipitation was recorded in northern Karelia and in southern parts of Lapland.
The snow cover was particularly heavy in an area extending from northern Karelia to the eastern parts of the county of Oulu and into Lapland. In some places the water equivalent of the snow cover was as high as 250 mm, and values in excess of 180 mm
were encountered over wide areas. The snow became compressed during the mild and rainy weather at the beginning of the month throughout the country. After the middle of the month the snow cover again increased.
Lake water levels in some larger lakes of central and eastern Finland were still below the seasonal mean. In other regions water levels were at least at the seasonal mean. The deviation of the level of lake Pielinen at the end of the month from the
mean February level during the period 1960-1999 was -3 cm, and corresponding figures in some other Finnish lakes were: Kallavesi +12, Saimaa -26cm, Keitele -13, Päijänne -13, Pyhä-järvi, Säkylä +15, Längelmävesi +16, Näsijärvi -6, Lappajärvi +21, Lentua
+18, Oulujärvi +6, Lokka +73, and Inari +40 cm.
The discharge of e.g. the river Vuoksi was still lower than normal. However, in many rivers of southern and central Finland the discharge increased in atypical fashion for the time of year, and eventually exceeded the seasonal mean. Discharges
increased in coastal zone rivers at the very end of the month as a result of melting of snow. The monthly discharge of the river Pielisjoki in February 1999 was 78 % of the seasonal mean during the period 1961-1990, and corresonding figures in some other
Finnish rivers were: Vuoksi 82 %, Kymijoki 91, Kokemäenjoki 144, Kalajoki 177, Oulujoki 117, Kemijoki 142 and Tornionjoki 141 %.
Groundwater and groundfrost
Groundwater levels remained clearly below the seasonal mean in groundwater formations of southern, central and particularly eastern Finland. In morraine soils groundwater abundance was at or above the seasonal mean, and the groundwater level even
increased in many areas, in contrast to the normal situation in winter. Groundfrost was shallower than normally in February. Depths of 10-30 cm were recorded in coastal areas, 0-15 cm in southern and central Finland extending even to southern Lapland and
10-90 cm in Lapland itself.
Lake ice thicknesses in February, with only a few exceptions, were still 5-15 cm less than the seasonal mean. In southern Finland ice thicknesses at the end of the month were about 30-40 cm, in central regions 40-50 cm and in Lapland 50-70 cm. Ice
thicknesses decreased at the end of the month in the south as a result of a period of warm weather occurring at this time.