Hydrologische Beobachtungen im Flyschgebiet beim Schwarzsee (Kanton Freiburg)

Birmensdorf

1965

S. 23-60

16 Abb., 12 Tab., 21 Lit. Ang.

Bandaufführung

157499

Two gaging stations in the Flysch-Region of the Swiss Pre-Alps near the Schwarzsee (Freiburg) have been in operation for research purposes since 1952. They measure continously the discharge of the watersheds Rothenbach and Schwändlibach. To measure precipitation a network of raingages has also benn installed. The data collected indicate generally much highe discharge rates in the Rothenbach than in the adjacentSchwändlibach, and the purpose of this paper is to discuss possible reasons for this obvious hydrological difference. The analysis of topography and relief of the two watersheeds shows a "warmer" exposure and orientation as well as a more regular relief for the Schwändlibach than for the Rothenbach. A correspondingly higher insolation has been calculated for the Schwändlibach. In the Rothenbach, however, we find large areas of swampy pasture land where annual precipitation has been found 10-15% higher than in the Schwändlibach. Differences in exposure, precipitation and wind conditions are indicated by the snow cover, resulting in a higher snow water storage an the Rothenbach in spring. Mean discharge values as well as hydrographs have been analysed. Low flow periods during fall and winters as well as the recession part of many hydrographs indicate greater groundwater storage and greater lw flow discharges in the Rothenbach than in the Schwändlibach. This might be due to lower insolation less evapo-transpiration losses, higher precipitation and larger area of swampy land. A frequency analysis of discharges shows the same tendency. Deep seepage inflow or outflow os probably not a reason to explain these hydrological differences. This investigationdoes not allow to relate quantitativelythe influence of single factors such as relief, radiation, precipitation, etc. to hydrologic effects. More field ivestigations and better quantitative interpretations of the dta collected will be necessary to do this. It is only possible, therefore, to discribe the entire effect of all the environmental factors together.