Proglacial geomorphodynamics on catchment scale with airborne/terrestrial laserscanning

Work package 5 of the PROSA project (High-resolution measurements of geomorphodynamics in rapidly changing proglacial systems of the Alps) coordinates the investigations of the four other work packages and cooperates with them in establishing the sediment budget of the Upper Kaunertal study area by regionalising localised measurements of sediment transport by various geomorphic processes along sediment cascades. The main aims of this work package for the next project phase are the following: 1.: Continuation of airborne (laserscanning, ALS; drone-based imagery for stereophotogrammetric analysis) and terrestrial (laserscanning, TLS) measurements, assessment and enhancement of data accuracy and reliability (e.g. the spatial distribution of measurement errors). In order to further optimise the quality of ALS data, natural ground control areas will be surveyed and employed for registration, using TLS; this is possible because of the enhanced absolute orientation of TLS surveys using the TLS radomes developed in the first project phase. The resulting digital elevation models are used to quantify surface changes between epochs, and to analyse and classify the topography on multiple spatial scales (from surface substrate to landforms), supporting the regionalisation of local- scale measurement results. 2. : Continuation of own measurements, and integration of the results of all work packages to establish the sediment budget of the study area. In order to reach this aim, the results of measurements conducted on test areas (on the local and hillslope scale) have to be upscaled to the whole catchment (regionalisation), using various methods such as simulation models, statistical approaches, and the analysis of the geomorphological and geotechnical map. The analysis of mapped and modelled sediment pathways leads to important insights into the interaction of various geomorphic processes that form sediment cascades in the study area, and a better understanding of the system (e.g. sediment connectivity). The temporal scale of the area-wide accounting of surface changes and process rates on the basis of multitemporal digital elevation models (generated from ALS surveys) will be extended by an elevation model to be generated from airborne imagery of the "Tyrolean Forest Monitoring Campaign" taken in the year 1953; this will enable the comparative analysis of short and longer-term process dynamics in relation with deglaciation and other factors. Finally, the sediment budget and its parts will be used to assess the relative contribution of glacial and non-glacial processes, for a comparative analysis of process rates in areas with different periods of time since deglaciation, and to judge the ratio of sediment transfer within and sediment export from the catchment; the latter quantity refers also to the sediment input to the Kaunertal reservoir. 3.: Additionally, this work package is in charge of coordination tasks for all work packages, most importantly the organisation and management of data collection and exchange, and the provisioning of digital elevation models, including the error assessment.

Aim of PROSA, (high-resolution measurements of morphodynamics in rapidly developing proglacial systems of the alps) is the investigation of the impact of the fast progressing glacial melting on the forms of the Earth's surface. The temporal development by erosion, transport and deposition of material is in the focus of the research project. Debris flow, rock fall and flooding are some of the possible consequences expected to increase because of ongoing climate changes. Within PROSA the relation among different geomorphological processes and their changes will be quantified as a sediment transport budget. This required the collaboration of different disciplines, including geomorphology, geology, geophysics and photogrammetry.The acquisition and processing of high-resolution spatial data in a temporal stable coordinate system was the main contribution by the research group Photogrammetry (Vienna University of Technology, funded by the FWF) to this project. This is a difficult task, especially because stable areas are rare due to the permanent changing of the surface (e.g. melting of snow and permafrost, debris flow). Laser scanner were used for the measurements primarily. As a rather new technology, laser scanning is one of the main fields of research in photogrammetry at the Vienna University of Technology. Laser scanning can provide dense and precise measurements of the terrain, either from the earth (terrestrial) or from above (aerial).Aerial laser scanning was used within this project for the measurements of the whole study area twice. Changes of the Earth's surface can be recognized by comparing these two data sets. Due to several error sources, the originally measured terrain points contain significant errors (up to several dm). An optimization method developed within this project reduces these errors to 1-2 cm. On the basis of this improved data, a detailed description of the present geomorphological processes was done by the involved disciplines in this project.For terrestrial laser scanning a new georeferencing method was developed within the PROSA project. This method can be used to adjust the terrestrial measurements with highest possible accuracy to the airborne laser scanning measurements. The method was provided to the science community as open source program. Multiple terrestrial laser scanning measurements were con- ducted within this project in order to observe terrain changes on specific slopes and to quantify material transports.The findings of the PROSA project lead to a deeper understanding of the ongoing processes in the Alps and consequently to a better assessment of natural hazards. In the end this increases the human protection from natural hazards.PROSA is a collaborative geoscientific project which is funded by the DFG (German Research Foundation / BE1118/27-2) and the FWF (Austrian Science Fund / I893-N24). The project was extended until 2017.