The effect of snow-cover area change, precipitation and temperature on streamflow in Tärnaån drainage basin, northern Sweden

Sammanfattning: Snow cover is a fundamental component of the world’s cryosphere and plays an important role in the hydrological cycle. It is significant as a human water resource but can also be an influencing factor in flood and drought generation. Snow cover shows a great variability and understanding local snow cover and its effect on streamflow is therefore of importance. In this study, the effect of snow-cover area (SCA) change, precipitation and temperature on streamflow and its variability during the season, is studied in Tärnaån drainage basin in northern Sweden with the aim to see whether streamflow levels in Tärnaån drainage basin are mainly controlled by SCA change, precipitation and temperature, or if it is necessary to also consider other influencing factors. This aim will be reached by using MODIS snow-cover data products derived from satellite imagery, meteorological and hydrological data for the drainage basin and by visually analysing SCA changes, streamflow, precipitation and temperature data as well as performing a Pearson moment-product correlation analysis between some of these variables. The results show that the effect of SCA changes, precipitation and temperature on streamflow vary over the studied time period which is also shown by differing correlation coefficients for different sub-periods. The strongest correlations are shown between SCA change and streamflow and between temperature and streamflow during sub-period 2 and sub-period 3 respectively. It is further clear that other variables than SCA change, precipitation and temperature influence streamflow and need to be considered to correctly predict streamflow levels in Tärnaån drainage basin.