CEDRENS EnviPEAK has entered its last year. It was a very exciting project with many partners working on the ecological effect of frequent flow fluctuations. The field site chosen for this project were Surna among some others. Surna is a strongly regulated river located 120km west of Trondheim, at the northern edge of Trollheimen. In 2010 we identified to sites at Surna river which has been subject to our investigations. Harang was a mildly curved reach and Svean a straight one. Both are characterized by a deeper, pool-like upstream part and a riffle-like downstream part. In addition, in both reaches, an island is present in the middle of the river. Since 2010, we are monitoring the bed and substrate changes as well as the discharge and water levels. This years measurement campaign starts in Mars with a week of topography and bathymetry measurement. Stefan Haun, Ingo Schnauder and Sonja Huber joined in and we went to Surnadal. The primary goal was to measure the bathymetry in order to quantify if there were bed changes happening. The secondary goal was to measure grain size distribution at the river bed via a photogrammetric analysis. In addition we brought the freeze core equipment and the LISST SL.
We were facing extreme weather conditions which made it difficult to access the site and conduct the measurements. We successfully measured the bathymetry and took underwater photos of the river bed but this was all we could do. The first two days the temperature was around zero degrees Celsius but the wind blew heavily and brought in heavy snow storms every other hour. The last three days we had clear sky but the temperature dropped to minus 18 degree so that the daily routine of starting the base station of the D-GPS and the other devices were quite painful for fingers and toes. However, we were very happy with the data we took. The kayak mounted with the M9 and the D-GPS proved to be a very handy and robust solution to measure the bathymetry. As far as it concerns the photogrammetric analysis with BaseGrain, I can only say that we are in a trial phase, both in taking good quality pictures and using the software. However we are getting somewhere.