On-line measurements provide more accurate estimates of nutrient loading: a case of the Yläneenjoki river basin, southwest Finland.

Automatic on-line measurement stations for water quality components and water level were equipped with dataloggers and GSM transmitters; the stations were installed at two sites in the Yläneenjoki river basin, SW Finland. Measurements during five seasons in 2006-2007 were conducted to find out whether the produced data would provide more accurate estimates of material and nutrient transport than traditional water sampling. Sensor-based monitoring estimates for transport of total suspended solids (TSS) were clearly higher (difference -6-61%), total phosphorus also higher, and that of nitrate (NO(3)-N) somewhat lower (difference (-51%-4%), as compared with manual sampling based estimates. The winter season studied here was mild i.e. winter-type which is becoming more common in Finland with the changing climate. Sensor-based monitoring proved its benefits particularly in such conditions.