Spatiotemporal variations of hyporheic temperature and its biogeochemical implications in a dam regulated river

Abstract:

Temperature plays an important role in modulating biogeochemistry in the hyporheic zone by controlling the dissolved oxygen concentration and microbial reaction rates. The quantification of spatiotemporal variations of hyporheic temperatures is important in understanding various hydrological and biogeochemical processes in river corridors. The endeavors by multiple field research campaigns in installing aquifer tubes along the shoreline of the Hanford Reach of the Columbia River provided abundant spatially distributed hyporheic temperature measurements over a 50km long dam-regulated river reach. Our recent survey using a new multi-depth dense aquifer tube array (a 100×30×3 m domain instrumented with nearly 70 thermistors) further informed significant spatiotemporal variations of hyporheic temperatures at the finer local scale that have not been identified before. In this study, we pursue a deeper and wider understanding of the hyporheic temperature characteristics in this typical dam-regulated river reach through model and data integration approaches, including 1) wavelet spectrum and clustering analysis to investigate the variability of the measured hyporheic temperature and its relation with sampled dissolved oxygen, nitrate and other biogeochemical species; 2) evaluation of existing models using hyporheic exchange flux estimation from the temperature measurements; 3) new conceptual model that captures the multiscale variations of the hyporheic temperature.