Field measurement of the erosion threshold of silty seabed in the intertidal flat of the Yellow River Delta with a newly-developed annular flume

Abstract

Accurately measuring the critical shear stress is crucial for numerous applications, such as sediment transport modeling, erosion prediction, and the design of sustainable coastal engineering structures. However, developing reliable and precise in-situ measurement devices faces significant challenges due to the harsh and dynamic nature of aquatic environments. Factors like turbulence and waves introduce complexities that must be considered when designing and calibrating these devices. The newly developed Openable Underwater Carousel In-situ Flume (OUC-IF) was used to determine the critical shear stress (τc) and quantify erosion rates. Acoustic Doppler Velocimeter (ADV) was employed to measure 3D near-bottom velocities, which were then used to estimate and pre-calibrate bed shear stress (τ) applied on the seabed in the annular flume. Three computation methods of shear stress were evaluated: turbulent kinetic energy (TKE), direct covariance (COV), and log profile (LP). In-situ erosion experiments were conducted for the first time at two sites in the tidal flat of the Yellow River Delta (site 1 with a water depth of 1.32 m and site 2 with a water depth of 0.75 m). The critical shear stress was found to be 0.10 Pa at site 1 and 0.19 Pa at site 2, and the erosion rates of the sediments were successfully measured. The effect of wave-seabed interactions on erosion resistance was explored by theoretically estimating the wave-induced pore pressure of the seabed based on the observed data. The max liquefaction degree of the seabed at site 1 and site 2 was 0.035 and 0.057, respectively, and the average erosion coefficient Me was 2.63E-05 kg m-2s-1 at site 1 and 3.48E-05 kg m-2s-1 at site 2.

Evaluation of water management after rehabilitation in the Terusan Tengah Swamp Irrigation Area, Kapuas Regency, Central Kalimantan

“…Deposition tends to occur when the bed shear stress (τ) does not exceed the critical shear stress value (τc). Understanding the critical shear stress (τc) is essential for identifying the threshold for sedimentation and erosion events, as well as for hydraulic modeling [18]. For fine silt material, the potential for erosion and deposition can be evaluated using the critical shear stress limit [19].…”

Evaluation of water management after rehabilitation in the Terusan Tengah Swamp Irrigation Area, Kapuas Regency, Central Kalimantan

“…Deposition tends to occur when the bed shear stress (τ) does not exceed the critical shear stress value (τc). Understanding the critical shear stress (τc) is essential for identifying the threshold for sedimentation and erosion events, as well as for hydraulic modeling [18]. For fine silt material, the potential for erosion and deposition can be evaluated using the critical shear stress limit [19].…”

Evaluation of water management after rehabilitation in the Terusan Tengah Swamp Irrigation Area, Kapuas Regency, Central Kalimantan

“…Deposition tends to occur when the bed shear stress (τ) does not exceed the critical shear stress value (τc). Understanding the critical shear stress (τc) is essential for identifying the threshold for sedimentation and erosion events, as well as for hydraulic modeling [18]. For fine silt material, the potential for erosion and deposition can be evaluated using the critical shear stress limit [19].…”

Evaluation of water management after rehabilitation in the Terusan Tengah Swamp Irrigation Area, Kapuas Regency, Central Kalimantan

“…Deposition tends to occur when the bed shear stress (τ) does not exceed the critical shear stress value (τc). Understanding the critical shear stress (τc) is essential for identifying the threshold for sedimentation and erosion events, as well as for hydraulic modeling [18]. For fine silt material, the potential for erosion and deposition can be evaluated using the critical shear stress limit [19].…”