Multi-year observations of near-bed hydrodynamics and suspended sediment at the core of the estuarine turbidity maximum of the Changjiang Estuary: the NP-ChaM campaign

Abstract. A comprehensive multi-year field campaign, the North Passage Channel Measurements (NP-ChaM), was designed and executed to enhance our understanding of the hydro- and sediment dynamics in the North Passage, the primary navigation channel of the Changjiang Estuary, China. The NP-ChaM campaign comprised eight observational sites and spanned 50 days, distributed over four years, including two dry seasons and two wet seasons. A series of tripod systems, equipped with multiple instruments, were deployed on the seabed to monitor near-bed physical processes reliably.

The resulting dataset comprises: (i) fluid motions, encompassing pressure, flow velocity and direction (at the bottom and throughout the entire water column), and wave patterns; (ii) near-bed environmental conditions, including temperature, salinity, and turbidity (at the bottom and across a near-bed 1-meter range); (iii) supplementary meteorological data sourced from credible providers; (iv) preliminary results from post-processing showcasing the practical application of the data, such as lateral flows and turbulent kinetic energy characterizations.

This dataset is especially valuable due to its extensive temporal and spatial coverage, and the high concentrations characterizing many of the observations (from several g/L to tens of g/L). Conducted annually from 2015 to 2018, the NP-ChaM campaign facilitated detailed observations of seasonal variations in environmental conditions and associated physical processes. The eight observational sites, positioned on either side of the deep channel, enables quantifications of channel-shoal exchanges, along-channel flow dynamics and saltwater intrusion. This dataset is suitable for advancing our understanding of along-channel and cross-channel dynamics in a channel-shoal system, and for calibrating numerical models. The dataset has undergone rigorous quality control to ensure reliability and accuracy.