<p>The river Maltsch / Malše is an interesting waterbody from a historical, hydrological and ecological perspective. As a border river between Austria and the Czech Republic, it has had an eventful history. With the political separation into “East” and “West” in the middle of the 20th century, a region that initially had a similar land use structure was completely changed. On the Czech side, villages and settlements were removed and the land expropriated. In the course of the fall of the Iron Curtain, the land was mostly sold to large landowners. Changes also took place on the Austrian side. Agriculture and forestry have been intensified over decades.</p><p>This leads to the situation that on both sides of the river, under very similar geological and hydrological conditions, the effects of very different land use developments and changes on the water household and erosion can be documented. Thus, a transboundary, mainly EU-funded INTERREG project was launched to investigate this variability in general and to address the implications for the sediment regime in such river systems (concerning e.g. flood protection control, sedimentation of reservoirs) in specific. Moreover, it is examined how mitigation measures for water retention, erosion control and climate change adaption can be planned under these variable boundary conditions. Especially droughts and heavy rainfall events must be considered as threats in the region in the future.</p><p>In addition to the changes described above, the political situation in the border region has left a refuge for nature. The Maltsch is part of the so-called Green Belt that stretches across the whole of Europe. A key species of the region is the Freshwater Pearl Mussel (Margaritifera margaritifera), which is characterised by its very high demands on the environment. It, therefore, serves very well as an indicator / umbrella species and thus also as a condensation nucleus of the different topics of the project.</p><p>In summary, the following aspects will be presented: (1) documentation of historic, political driven land use changes and land use differences on GIS basis, (2) effects on soil erosion by means of modelling via USLE, (3) estimation of the effects on the landscape hydrology and (4) effects on the aquatic fauna, especially the key species Freshwater Pearl Mussel.</p>

<p>The intensification of agriculture over the last 50 years together with a constant change in climatic conditions has resulted not least in a deterioration of the aquatic habitat due to sediment input and siltation in the upper reaches of Bavarian streams. Concerned about this development, the  Fisheries Association Bavaria has launched a project to investigate the main causes of erosion on agricultural land.</p><p>By comparing aerial photographs from the 1960s with current orthophotos, by means of a detailed GIS-analysis, the size of agricultural plots in five representative catchment areas was first investigated. In a further step, erosion modelling based on the Universal Soil Loss Equation (USLE) was implemented in two catchment areas.</p><p>The intersection of the digitalized land uses from the two time steps showed that despite an almost constant proportion of arable land in the catchment area, the length of the fields had been increased by a third on average and their extent had at least doubled, due to wide-ranging changes in the landscape structure.</p><p>By considering the soil loss in the 1960s, that under today's conditions, and by modelling scenarios with conserving farming technics and further-reaching retention measures, conclusions can be drawn as to which measures will be necessary in the future to enable effective soil and water protection.</p><p>The erosion modelling showed that the average long-term soil loss - as a result of the USLE - currently exceeds a value of 40 t/ha*a under conventional farming in vast areas of the arable land. Likewise, even with conservation tillage (no-till), isolated erosion spots of more than 20 t/ha*a occur. Since a simple change to soil-conserving cultivation (reduction of the cultivation factor C) will not be sufficient to prevent future erosion events (increased precipitation erosivity R) and constant soil loss, targeted measures (improvement of the erosion protection factor P) against soil erosion must be implemented. This includes nature-based retention measures as wetlands, buffer strips or green waterways. All of which will also help to tackle the upcoming impacts of the Climate crisis. The chosen model supports the localization of the source of erosion as well as the selection and implementation of targeted measures.</p>