lnvestigations to study hydrologic characteristics in small partly forested catchments of the Alptal valley in Switzerland started 10 years ago. Out of 11 catchments, 0,5 to 3.2 km2 in area, three are under continuous, long term, three under continuous, temporary observation, and five are being investigated using periodic sampling procedures.
Weather and climate conditions are very similar in all catchments. Hydrologic parameters are studied to find their variation in time as well as between catchments. Subalpine spruce forests, pasture and wetlands are the main vegetation types, all under extensive use.
The temperature of stream water and the amount snowpack water are examples which demonstrate the annual variation of hydrologic parameters. Precipitation and stream flow, as well as electrical conducivity of streamwater and transport of dissolved solids, are the examples used to indicate differences of hydrologic behaviour belween catchments.
The study of both the variability of hydrologic parameters in time and differences between catchments calls for longterm maintenance of hydrologic investigations.