Details

Autor(en) / Beteiligte

• Sandoval, Jorge
• Mignot, Emmanuel
• Mao, Luca
• Pastén, Pablo
• Bolster, Diogo
• Escauriaza, Cristián

Titel

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

Ist Teil von

• Journal of geophysical research. Earth surface, 2019-04, Vol.124 (4), p.938-959

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2019

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• 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. Key Points Large‐scale turbulent coherent structures are the fundamental mechanisms of transport between surface storage zones (lateral recirculation areas) and the main channel in rivers A combination of field measurements and 3‐D numerical simulations provides a better understanding of the flow field and transport in the recirculation zone Three global mass transport models are used to study the exchange processes and represent the temporal evolution of solute concentration