Sensitivity of River Channel Morphology to Streamflow Regimes in Small Piedmont Watersheds

Keywords: Channel morphology, sensitivity, Piedmont province, streamflow, seasonality
Abstract Type: Paper Abstract

Abstract

We study the sensitivity of specific channel capacity (capacity of channels at specific discharge values) with regard to streamflow regimes in small Piedmont watersheds. Twenty years of channel change is assessed using specific-gage analysis based on United States Geological Survey (USGS) rating curve calibration data from fourteen sites (< 500km2 drainage area). We compare observed changes to the hydrological record using regression modeling to suggest potential drivers of change and infer sensitivity. Our results reveal coherent sub-decadal variability as well as decadal signal in the specific capacities of our sites over time (1999―2020). The trendlines from the specific-gage plots equally indicate that an average of six sites are increasing in their capacities while the remaining eight sites may be reducing. Bed elevation data suggest changes in channel depth are more important than width changes in explaining the capacity records. Our inference from regression results comparing annual change in specific channel capacity and a variety of streamflow metrics including average monthly discharges (R^2 0.3―0.8) is that a single dominant control common to all sites is unlikely. More generalized controls may be discernible for observed coherent decadal trends.