Flusskorridore und Auenstrukturen im schweizerischen Mittelland (nördliches Alpenvorland) | River corridors and alluvial structures in Central Switzerland (northern sub-alpine area)
Long-term spatial variation of river channel distribution in this alluvial valley zone is described for two examples by analysing historical maps covering a period of over 300 years. Such a time series enables the identification of the occupied river corridor or «Pendelband». Two river sections in northern Switzerland were chosen, one of the Aare river and one of the Reuss river to analyse the spatial evolution of the river channels over time, as well as alluvial structures. Knowledge of the river corridor as an historical reference give us an important guideline when developing appropriate regional measures for river restoration projects.
Die Abflussregimes der Schweiz
Die Abflussregimetypisierung der Schweiz fuhrt zu 16 Regimetypen, welche sich quantitativ beschreiben und in ihrer raumlichen Verbreitung festhalten lassen. Dadurch ist es nun moglich, in Einzugsgebieten (10-500 km2) ohne Direktmessung eine Abschatzung des mittleren Abflussverhaltens und der damit verbundenen Richtwerte zu erhalten. Methodisch wurden konventionelle Typisierungsverfahren und Verfahren der Distanzgruppierung z.T. kombiniert angewendet. Die raumliche Umsetzung gelingt in den alpinen Gebieten mittels der arealen Vergletscherung und der mittleren Einzugsgebietshohe; uber den letzteren Parameter lassen sich auch die sudalpinen Regimetypen raumlich einordnen. Im Mittelland geschieht die raumliche Festlegung der Typen mittels FOURIER- und Trendflachenanalyse. Es wird die praktische Bedeutung dieser Abflussregimetypisierung aufgezeigt.
Spatial distribution of interstitial assemblages in the floodplain of the rhǒne river
Interstitial invertebrate assemblages of the Rhǒne River were studied at the scale of the entire alluvial plain. Ten stations, located in five former channels, were sampled with a Bou-Rouch pump at 50 and 100 cm depth. The chemical characteristics of the interstitial water allowed the differentiation of stations without hydrological connections with the subterranean habitats, stations fed by surface water coming through the bank sediments and stations fed by true groundwater. The faunal assemblages reflect the difference between connected and isolated stations but did not demonstrate any differences related to the origin of the water. In fact the interstitial assemblages are distributed along a gradient from the margin of the floodplain (stations with a high physical stability associated with the absence of flood periods) to the area close to the main channel regularly influenced by floods. These results demonstrate that both groundwater characteristics and the position of the station in the floodplain influence the spatial distribution of interstitial fauna in the alluvial valley of the Rhǒne River.