Sediment resuspension mechanisms and their contributions to high‐turbidity events in a large lake

Abstract

High-resolution field data, collected during April to October of 2008-2009, were analyzed to investigate the quantitative contribution of sediment resuspension to high-turbidity events in central Lake Erie. Resuspension events were distinguished within high-turbidity events according to turbidity, fluorescence and acoustic backscatter timeseries, as well as satellite images. We observed 16 high-turbidity events, causing a total duration of 20 d (out of 344 d) with elevated nearbed turbidity (> 10 NTU). Of these events, 64% were correlated with algal biomass, with the remaining 18%, 5%, and 4% being attributed to sediment resuspension by surface waves, storm-generated currents and enhanced nearbed turbulence induced by highfrequency internal waves, respectively. This is the first time that resuspension by enhanced nearbed turbulence from high-frequency linear internal wave degeneration has been observed in a large lake. Resuspension was parameterized as a function of the instantaneous critical bottom velocity, bottom shear stress and the Shields parameter. From the in situ measurements, we suggest an extended Shields diagram for silty bed material that can be used to predict resuspension in other aquatic systems with similar sediment composition (20% cohesive sediment).

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

“…Large storms are known to cause benthic storms at great depths (e.g., Gardner et al, 2017). Valipour et al (2017) correlated maxima in ADCP signal amplitude to individual resuspension events in Lake Erie, similar to the event recorded at OC26 during the passage of Hurricane Isaac. Current meter data presented by Spencer et al (2016) indicate propagation of near-inertial energy from Hurricane Isaac into the water column at M1, M3, and M4 affecting currents near the seafloor at >1,250 m water depth (Figure 7) and producing bed shear stress of 0.06 to 0.1 Pa and peak velocities of 23 cm s -1 at the current meter (Figures 14-17).…”

“…Light green bars mark the collection intervals that sampled small-scale resuspension events in the near field; dark green bars mark the collecting periods that correspond to the far-field small resuspension events of 23 profiles spanning 5 years we observed a BNL 21 times ( Table 1). Sediment resuspension events occur from all depths of the seafloor and in a variety of environments, including large lacustrine environments (Valipour et al, 2017), and coastal and deep open ocean areas (Gardner, 1978;Gardner et al, 1984Gardner et al, , 1985Gardner et al, , 2017Walsh et al, 1988;Bonnin et al, 2002Bonnin et al, , 2005Bonnin et al, , 2006Bonnin, 2004;Puig et al, 2004Puig et al, , 2012Puig et al, , 2013Peine et al, 2009;Ross et al, 2009). Benthic nepheloid layers formed by erosion and resuspension of material from the seafloor are thus also found at all depths in the world ocean.…”

Wind and rainfall regulation of the diffuse attenuation coefficient in large, shallow lakes from long‐term MODIS observations using a semianalytical model

“…The floating algal bloom area was masked by FAI index [ Hu , ; Hu et al , ] due to the algal bloom preventing light from penetrating the water, such as in the northwest and southwest parts of the lake. High K d (490) values in summer (6 and 15 July 2007 in Figure ) were mainly caused by algal growth [ Valipour et al , ]. Low K d (490) values were distributed beyond the algal bloom area, such as in the center of the lake.…”

High‐turbidity events in Western Lake Erie during ice‐free cycles: Contributions of river‐loaded vs. resuspended sediments

“…(1) Fukuda and Lick (); (2) Lee et al (); (3) Lick et al (); (4) Lou et al (); (5) Cardenas et al (); (6) Hawley and Eadie (); (7) Harris et al (); (8) Hawley et al (); (9) Morales‐Marin et al (); and (10) Valipour et al ().…”