Implementation of automatic sensors for continuous monitoring of runoff quantity and quality in small catchments

Development of new automatic sensor-based techniques has expanded the possibilities for intensive monitoring of water quality in small catchments. In this study turbidity and concentration of nitrate-N were monitored with probes in the Savijoki catchment, which has been observed with traditional methods for decades. Particular attention was paid to implementation of the equipment, calibration of the probes and calculation methods. All equipment functioned technically well during the one year monitoring period. Calibration of turbidity and nitrate-N proved that the sampled values agree well with the probe results. However, it seems that loading estimates made with the traditional method arc not very reliable for individual years. The research period in this study was exceptional with its many runoff peaks in winter. It is not possible to catch the peaks with traditional monitoring, why the results and comparisons between automatic probes and traditional monitoring cannot be generalized. However, the results proved that novel monitoring techniques have to be continued and extended. In further studies the calculation methods need developed and improved to be to get reliable loading estimations from the sensor data as simply as possible. In a changing climate, the monitoring, loading estimations, and consequently the assessment of the effect of agricultural water protection measures will probably turn even more difficult and challenging.