The use of continuous sediment‐transport measurements to improve sand‐load estimates in a large sand‐bedded river: The lower Chippewa River, Wisconsin

Accurately determining sediment loads is necessary for managing river environments but difficult because multiple processes can lead to large discharge-independent changes in transport. Thus, estimations of load using discharge–sediment rating curves fit sparse or historical sediment-transport measurements be inaccurate, necessitating alternative approaches reduce uncertainty. Continuous uncertainty they used detect transport and are therefore unaffected by hysteresis. We largely continuous measure sand the lower Chippewa River, a sand-supplying tributary Mississippi River. side-looking acoustic-Doppler profilers continuously suspended-sand concentration, bedform-tracking techniques episodically bedload Bedload was then estimated discharge-dependent ratio This approach allowed determination that were not based only on water discharge. Our show hysteresis between discharge concentration occurs during most floods. Quasi-continuous bed-elevation scour monitor lags dune geometric adjustment also common, causing Furthermore, comparisons our with indicate declines both since 1980s. These findings non-stationary function over timescales ranging from within individual floods decades. Consequently, although continuous-measurement yields ~20–30% improvement rating-curve estimates multi-year periods, up factor-of-five sand-load shorter, flood timescales, which largest occur.