Field and Numerical Investigation of Transport Mechanisms in a Surface Storage Zone

TY - JOUR

T1 - Field and Numerical Investigation of Transport Mechanisms in a Surface Storage Zone

AU - Sandoval, Jorge

AU - Mignot, Emmanuel

AU - Mao, Luca

AU - Pasten, Pablo

AU - Bolster, Diogo

AU - Escauriaza, Cristian

PY - 2019/5/19

Y1 - 2019/5/19

N2 - In-stream surface storage zones (SSZs) caused by lateral recirculation areas play a significant role in the transport and fate of contaminants in rivers. Lateral recirculating areas have long residence times that favor nutrient uptake, accumulation of pollutants, and interactions with reactive sediments. In watersheds affected by acid-mine drainage, SSZs have profound effects on biogeochemical processes, controlling the local concentration and distribution of toxic elements along the channel. Despite the importance of turbulent flow dynamics on these processes, limited work has been carried out to analyze mass transport in natural SSZs with complex geometries. In this investigation we study a SSZ in the Lluta River, located in a high-altitude environment in northern Chile, by coupling field measurements and 3-D numerical simulations to understand the transport mechanisms with the main channel. We measure the velocity field using an acoustic Doppler velocimeter (ADV) and large-scale particle image velocimetry (LSPIV), extracting the bathymetry from digital image processing. Using these data, we perform detached-eddy simulations (DES) to analyze the mean flow, turbulence statistics, and the dynamics of large-scale coherent structures. From this detailed description of the turbulent flow, we study the mass exchange and the time evolution of the mean concentration of a passive scalar in the SSZ by testing three upscaled models: a classical linear transport model, a two-storage formulation, and a fractional transport model. The analysis integrates temporal and spatial scales to provide a new perspective on the turbulent flow in SSZs and their effects on global mass transport in rivers.

AB - In-stream surface storage zones (SSZs) caused by lateral recirculation areas play a significant role in the transport and fate of contaminants in rivers. Lateral recirculating areas have long residence times that favor nutrient uptake, accumulation of pollutants, and interactions with reactive sediments. In watersheds affected by acid-mine drainage, SSZs have profound effects on biogeochemical processes, controlling the local concentration and distribution of toxic elements along the channel. Despite the importance of turbulent flow dynamics on these processes, limited work has been carried out to analyze mass transport in natural SSZs with complex geometries. In this investigation we study a SSZ in the Lluta River, located in a high-altitude environment in northern Chile, by coupling field measurements and 3-D numerical simulations to understand the transport mechanisms with the main channel. We measure the velocity field using an acoustic Doppler velocimeter (ADV) and large-scale particle image velocimetry (LSPIV), extracting the bathymetry from digital image processing. Using these data, we perform detached-eddy simulations (DES) to analyze the mean flow, turbulence statistics, and the dynamics of large-scale coherent structures. From this detailed description of the turbulent flow, we study the mass exchange and the time evolution of the mean concentration of a passive scalar in the SSZ by testing three upscaled models: a classical linear transport model, a two-storage formulation, and a fractional transport model. The analysis integrates temporal and spatial scales to provide a new perspective on the turbulent flow in SSZs and their effects on global mass transport in rivers.

U2 - 10.1029/2018JF004716

DO - 10.1029/2018JF004716

M3 - Article

SN - 2169-9003

VL - 124

SP - 867

EP - 1053

JO - Journal of Geophysical Research: Earth Surface

JF - Journal of Geophysical Research: Earth Surface

IS - 4

ER -