Assessing the magnitude and frequency of hydrological processes and their effect on threshold channel morphology, North Bosque River, TX.

Abstract

The North Bosque River (NBR) is a dynamic fluvial system experiencing geomorphic change resulting from hydrological and sedimentological influences. This thesis describes the forces that influence hydrological and geomorphological shifts along the NBR corridor, emphasizing the relationship between the frequency and magnitude of high flow events. An increase in NBR mean daily discharge from 5.6 to 8.4 m3/s is attributed to a historical 100-yr flood recorded in late 1991. The NBR’s geomorphic response to flow increases are primarily observed as planform and slope profile changes. Vertical profile changes are limited by the presence of rigid beds, which degrade at a rate of 0.73 mm/yr. Planform erosional assessments indicate that NBR cutbanks are shearing at 0.5 to 0.75 m/y. The NBR’s slope increased and sinuosity decreased from 1995 to 2019. These morphological and hydrological changes characterize the NBR’s response to a historical flood event.