Recovering head and flux distributions at the sediment-water interface for arbitrary, transient bedforms by inversion of photographic time series

Abstract

We consider streambed head and flux distributions induced by hyporheic exchange flux through irregular and dynamic natural sand bedforms. It has not previously been feasible to study these in the laboratory owing to incompatibility between fixed-location pressure transducers and shifting sand bedforms. We address this problem, presenting a noninvasive technique for regularized inversion of photographic time series of dye front propagation in the hyporheic zone to recover head and flux distributions, compatible with arbitrarily-shaped, generally transient bedforms. We employ the technique to analyze three bench-scale flume experiments performed under different flow regimes, presenting a new data set of digitized bed profiles, corresponding head distributions, and dye fronts. To our knowledge, this is the first such data set collated for naturally-formed sand bedforms.