Publications

Abflussmessungen Mittels Videos.

Mit kurzen Videosequenzen von Überwachungskameras und Smartphones können Oberflächengeschwindigkeiten in Abwasserkanälen gemessen werden. Eingesetzt wird dabei die bildbasierte Methode namens Surface Structure Image Velocimetry, kurz SSIV. Die resultierenden Ergebnissestimmen gut mit Ultraschall-Referenzmessungen überein und unterstreichen das Potenzial der innovativen Methode.

Oberflächenabflussmessungen im Urbanen raum mittels Videomaterial von Überwachungskameras.

Messungen von Oberflächenabflüssen werden selten im urbanen Raum durchgeführt, weil tradi­tionelle Messgeräte zu teuer sind oder direkt über oder innerhalb des Fliessgewässers installiert werden müssen. Deswegen sind Daten über Überschwemmungen im urbanen Raum nur selten vorhanden, was die Kalibrierung und Validierung von Überflutungsmodellen erschwert. In dieser Studie wird ein Ansatz vorgestellt, bei dem marktübliche Überwachungskameras zur Durchfluss­ messung eingesetzt werden.

Evaluation of the DischargeApp: a smartphone application for discharge measurements.

Herein we present a study that evaluates the DischargeApp to gauge water flow rates at 20–120 L/s in a clear water laboratory flume. In comparison to gauges of a magnetic flow meter the resulting absolute measurement error shows to be ±10 L/s, while for more of 85% of the measurements, the relative error is below 15%. This acceptable error, together with its simplicity and low cost characteristic, rank the DischargeApp as an ideal device for fast measuring of discharges. The DischargeApp has, therefore, the potential to gather useful and much needed hydrometric data in order to globally improve water resources management.

Urban overland runoff velocity measurement with consumer-grade surveillance cameras and surface structure image velocimetry.

Here we investigated the potential of using surveillance camera footage to measure surface flow velocity thanks to the Surface Structure Image Velocimetry (SSIV). Seven real-scale experiments conducted in a specialized flood training facility were used to test the SSIV method under varied and challenging conditions. In the best conditions tested, SSIV and conventional flow sensors differed by only 1.7% (0.1% standard deviation). While the method proved sensitive to light conditions, our results suggest that infrared lighting could be used to increase measurement consistency. Our study concludes that for measuring overland flow velocity in urban areas, surveillance and traffic cameras can be used.

Mobile device app for small open-channel flow measurement.

We present a mobile device app to measure discharge in open channels. With this tool flow data can be collected reliably and cheaply. The technology, on which the app is based, is derived from an already implemented and tested similar webcam application. The methodology has been tested for the webcam application in a pilot project in Switzerland. The results show that it is capable to produce continuous and reliable data for water level, surface velocity and runoff. The accuracy is within 5% of data obtained from a commercial radar sensor. The existing preliminary results for the smartphone application indicate similar accuracy. The tool has the potential to become the state of the art method for mobile runoff measurements, as it is truly high-tech and low-cost.