1. Abstract
The purpose of this study is to investigate the effect of the bed slope on the hyporheic flow.
At the same time, this thesis gives insight into the interaction between the hyporheic flow
and the sediment transport.
The theoretical framework behind this research is built upon the laws which govern the
subsurface flow and the sediment transport. To begin with, the techniques of flow tracing
and the PIV method are introduced in the effort to measure the velocity of the subsurface
and surface flow, respectively.
This thesis first examines the properties of the channel’s bed, focusing on the estimation of
the hydraulic conductivity. Then the main experiments are conducted by applying the
selected flow tracer- Rhodamine 6G dye- and the PIV technique in the channel and by
measuring the sediment transport.
The results of the experiments using the rhodamine dye show that the increase of the
channel’s slope leads to the increase of the ratio of the hyporheic flow to the total flow and
that the subsurface flow follows a Forchheimer curve rather than Darcy’s law. By applying
the PIV technique, the velocity profile of the surface water is calculated and it is observed
that complex interactions appear in the surface-subsurface water interface that may affect
the sediment transport.
Keywords
Hyporheic flow, hydraulic conductivity, Darcy’s law, Darcy-Forchheimer equation, PIV