Spatial Variation of Alluvial and Bedrock Channel Type in the Upper Guadalupe River, Texas
Abstract
<p>This dissertation investigates the spatial distribution of
alluvial and bedrock channel types in the Upper Guadalupe River in
central Texas. The objectives of this work are to investigate the
controls on the spatial distribution of alluvial-tending and
bedrock-tending reaches and gravel bars in the Guadalupe River.
Through traditional field and statistical techniques, this research
examines channel reach type and depositional landforms. The purpose
of this research is to investigate watershed scale controls on the
distribution of reach type in a mixed alluvial-bedrock channel in
central Texas and to explain observed differences between alluvial
and bedrock reaches. Observed differences between reach types
include the distribution of depositional landforms, channel
planform geometry, and channel width.</p>
<p>A comparison of reach characteristics between alluvial and
bedrock reaches is presented including slope, reach length and
transitions, sinuosity and floodplain width. An analysis of bar
characteristics including their spacing, type, and grain size is
also included. The spatial distribution of geologic and soil units
in the study area are compared for the correlation to different
channel reach types or transitions. Results that pertain to human
effects on the fluvial geomorphology in the study reach are
presented and separated from the natural processes. The
distribution of forcing agents, including roads and dams, is
included. The natural forcing effects of tributaries are also
addressed. The combined processes of bedrock incision and sediment
transport are active in creating the mixed alluvial-bedrock fluvial
landscape of the Upper Guadalupe River. Rivers in the Balcones
Escarpment region in central Texas are unique with respect to
climate, hydrology, and sediment supply. This research aims to
provide a foundation to build a conceptual model of mixed
alluvial-bedrock fluvial landscape evolution in central Texas.</p>