Using Leading-Edge Deep-Sea Survey Technique to Validate the Sediment Transport Model in the Dominguez Channel Estuary
Dominguez Channel Estuary (DCE) is a soft bottom channel that is regulated by the Dominguez Channel Toxic Pollutants Total Maximum Daily Load (TMDL). This TMDL includes numeric targets to protect the waterbody from sediment-bound pollutants that may negatively impact the marine benthos and fishes. Therefore, the sediment and pollutant fate and transport along the DCE play a critical role in determining the sediment management actions for TMDL compliance. The Dominguez Channel Sediment Transport Study (Study) was conducted to determine the average sediment deposition rates along the DCE. A previously developed hydrodynamic and sediment transport model, namely the Water Resource Action Plan (WRAP) model, was used in the Study to simulate sediment movement in the estuary. One of the study objectives was to validate the WRAP model input parameters and output results via various field techniques. The project team was able to think out-of-the-box to bring in the technique that had only been used in deep-sea surveying. In 2018-19, a comprehensive bathymetry survey involving side-scan, single-beam, and multi-beam sonars were conducted along the entire length of the DCE to obtain sediment profile data. Pairing the Global Positioning System unit with real-time kinematic correction, the field crew was able to survey, correct and record real-time sediment profile data from a survey jon boat. A massive amount of sonar data was then processed in the Geographic Information System software to calculate the sediment depth accumulated in the estuary. In addition, flow rate and sediment loading that entered into the DCE were quantified at seven monitoring locations over a six-month period. The monitoring data was compiled and compared with the WRAP model’s input and output parameters. The results revealed that the WRAP model was calibrated correctly and was suitable for conducting long-term sediment simulation in the DCE. The success of the Study underscores the importance of conducting field validation when running a watershed model. More importantly, the Study re-defined how sediment monitoring could be conducted in the future with high precision and confidence that echoed with the 2020 CASQA Annual Conference Theme. During the presentation, audiences will receive an immersive experience by watching the high-definition underwater camera footages and drone footages to visualize the unparalleled challenges the field crew was facing in DCE.