The objective of this paper is to study long-term variations in runoff and flood frequency in Sweden. Runoff over the 20th century increased by about 4% on average, but the trend was not statistically significant. The runoff during 1981-2000 was about 8% above the century average, but runoff in the 1920s was also as high. Records from the 19th century indicate that runoff was higher then, but temperatures were lower. The combination of high temperatures and high runoff in recent years is quite different from earlier records. The increase in the average level of annual floods in northern Sweden was larger, about +10%, but problems with the reliability of older data made it difficult to conclude that the change is in fact significant. The average increase at a selection of the most reliable stations was considerably smaller.
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