Identifikasjon av step-­pool geometri ved bruk av differensiell GPS i Vekveselva : et sammenlignende studie av en bratt fjellelv i Trollheimen, Norge, med eksisterende litteratur

Abstract

Steep mountain streams have traditionally received less attention than larger, alluvial streams due to resources such as fish in lowland rivers. In a wetter and wilder future there’s a need for increased attention regarding mountain streams to understand their properties during flood, and thereby limit damages in the downstream direction. Investigation of step-pools, which is a fluvial and climate-sensitive landform, can give important information concerning streams in mountainous areas. This thesis identifies the step-pool geometry in Vekveselva, a steep mountain stream in Trollheimen, Norway, and investigates how it can be compared to existing literature. Step-pools and their geometry were identified by application of a differential GPS over a one-year period, leading to a combination of longitudinal and cross-sectional profiles. Geometry was further investigated by a correlation analysis to see how different parameters covariate. Step-width is narrower than pool-width in Vekveselva, and pool-length correlates with parameters such as grain size. Pool-width seems to correlate with dimensions for height and grain-size in the upstream step. These correlations can be compared to existing literature were there are found similar results from other areas. In contrast there’s no covariance between parameters such as step-height and grain size, or drop- height and pool-depth, which contradicts existing literature. It is concluded that step-pool geometry in Vekveselva shows both similarities and dissimilarities with other empirical studies, and that dimensions for width and length in pools seems to covariate with step-height and grain-size.