| dc.description.abstract | This thesis aims to investigate the factors controlling the dynamics of temporary streams, i.e.,
streams that do not flow throughout the year. Temporary stream hydrology is a relative
unexplored scientific field. The field work for this thesis was conducted in a pre-alpine
headwater catchment, the Lümpenenbach, in canton Schwyz, Switzerland. The streams were
first mapped and then divided into segments. During ten surveys, each segment was assigned
one of six flow types (dry, wet, weakly trickling, trickling, weakly flowing and flowing). By
comparing the results from the mapping with topographic indices, in particular the
Topographic Wetness Index (TWI) and upslope accumulated area, the effect of wetness and
topography on the presence of water in temporary streams could be found.
The study was conducted during a limited timeframe and therefore only event-based changes,
not seasonal changes, could be studied. The conditions during the field campaigns had a
relative small effect on the flowing stream length because of the short timeframe of the study
and the relative stable weather conditions and low temperature. The discharge changed 2.8
times between the driest and wettest field campaign. Based on field observations, the stream
network reacts quickly to rain fall events, both with a quick response, and a fast drainage and
recession. However, there are some smaller areas where the stream initiation mainly is driven
by springs, resulting in a slower recession. The Lümpenenbach main stream is a perennial
stream, and were always flowing. The flowing stream length varied 1.4 times during the
surveys. There were a higher spatial and temporal variation in the stream state for the small
tributaries. There is a clear relation between the topographic indices and the likelihood of a
stream segment flowing: a higher topographic index value increases the chance for a stream to
flow. | sv |
