Modeling channel erosion in cohesive streams of the Blackland Prairie, Texas at the watershed scale.

Stream bank erosion is a product of submerged and subaerial processes. The goal of this research was to assess the application of the submerged jet test to predict erosion of cohesive stream banks in the Blackland Prairie of North Central Texas, an area with over 40% of the State’s population. In situ erosion monitoring was conducted by utilizing erosion pins and water level loggers at seven field sites with contributing drainage areas of 5-239 square kilometers. Erosion pins were placed at two locations on the cutbank wall and monitored over one year. Erosion rates during the monitoring period were a function of bank height and flow duration. Submerged jet test values from samples taken at the same locations as the erosion pins predicted erodibility of the material ranged from 0.0034-0.0065 cm3/N-s. Erosion pins indicated 30.35-572.00 mm of loss. The predicted erosion coefficients from the jet test, tractive force, and cumulative flow duration was within 31% of the field erosion. This study evaluates the first in situ testing of the erodibility of cohesive stream banks with cumulative flow duration, cumulative tractive force, and subaerial processes.