Around the start of this year the disicion was made to install new measuring weirs. These weirs are designed according to the "Field manual for research in agricultural hydrology" from the United States Department of Agriculture (Handbook number 224). By evaluating the existing measurements over the past eight years, it was decided to use modified H-Flumes. These modified H-Flumes can measure higher flows through raised walls. Other advantages are less welding work and therefore little warping of the stainless steel, and not to forget the price-performance efficiency.
The calibration process for establishing the water level-discharge relationship can be seen in the pictures.
Shallow core drilling to confirm the occurence of biogeochemical hotspots delineated with geophysical imaging
On 14th of November, two boreholes with depths of 8 and 6 m respectively, were drilled at the HOAL site next to the stream in the alder forest area. Previous geophysical investigations in this area have revealed a significant anomaly characterized by high induced polarization signatures, which so far has been interpreted as the accumulation of biominerals such as iron sulfides associated to the occurrence of a biogeochemical hot-spot.
Such hot-spots are spatially constrained areas associated with disproportional high rates of microbial activity and the enhancement of biogeochemical processes, such as the precipitation of minerals as metabolic products. As part of the research activities, we have been working on the development of geophysical methods to delineate the occurrence and geometry of such hot-spots; thus, the two boreholes were planned to compare the geochemical status of the sediments from material recovered within the expected biogeochemical hot-spot, and a control point away of the geophysical anomaly.
Initial analysis of the sediment reveal large contents of organic matter in the materials within the geophysical anomaly, which are not observed in the material recovered in the control drill. Further analysis in the laboratory will be conducted to gain detailed information about physical and geochemical parameters, as required to for the quantitative interpretation of the geophysical data.
On the 5th of June, a group of students of the Vienna Doctoral Programme on Water Resource Systems, with a research interest focusing on hydrology, visited the Hydrological Open Air Laboratory, HOAL. They got an introduction about the history and ongoing projects of the Institute for Land and Water Management Research. Then they visited the laboratories of the Institute, to learn about the experiments and physical and chemical measurements conducted there. Then the Hydrological Open Air Laboratory was introduced by the HOAL manager, which was followed by an excursion to the catchment, where the students learnt about the long-term and specific field measurements and the general instrumentation of the catchment. Some pictures from the day:
On 17th of April there was a big maintenance at the HOAL weather station with repairing and maintaining equipment like humidity, temperatur and wind sensors. Casings of data and power supply cables were checked for damages, which e.g. sometimes can occur by animals. Also the weather conditions in winter can cause broken cables which needs to be repaired.
Professor Thomas Dunne is an expert of fluvial geomorphology and hydrology, working at the University of California, where he is currently conducting his own research in theoretical studies in hillslope evolution, and sediment transport and river-basin sediment budgets. On Monday, the 15th of April, the Institute of Hydraulic Engineering and Water Resources Management (TU Wien) under the direction of Prof. Günter Blöschl, and the Federal Agency of Water Management (BAW) had the pleasure of hosting him for a meeting on the responsibilities of the Hyrological Open Air Laboratory (HOAL), and an introduction of the Vienna doctoral Programme on Water Resource Systems managed by the Vienna Technical University.