In the Danube Delta, on the Sulina branch, the morphology, sediment, and bedform characteristics were investigated. Three-dimensional (3D) bathymetry, flow velocity, suspended-load concentration, and liquid and solid discharge data were acquired throughout several cross sections along the Sulina channel, in order to investigate the distribution of water and sediment discharges and their influence against the river bed. A single observation (in February 2007) was made regarding the geometry, sediment composition, and hydraulic conditions under which the dunes grew and degenerated. The investigation focuses here mostly on the geometrical parameters of these bedforms, such as height, length, as well as grain size characteristic of the sediment and water dynamics. Based on in-site measurements, different hydraulic parameters were calculated, such as bed shear stresses and Reynolds number. During the field campaign, the measured water mean velocity was from v = 0.22–1.13 m∙s⁻¹. At the same time, the measured range of shear stresses within the dune field formation was from τ₀ = 2.86 N·m⁻² (on the cutoffs) to 8.62 N·m⁻² (on the main channel). It was found that the correlation between height (H) and length (L) of the Sulina branch dunes describes the formula: H = 0.093L^0.5268. The bedforms of the Sulina channel are, in general, developed in fine sand (D₅₀ between 0.06 and 0.35 mm).

We present geochemical analyses (major, such as CaCO₃, TOC, Fe₂O₃, and minors such as MnO and TiO₂) and trace elements, as well as some trace elements with genetic significance (Rb, Sr, Zr) or toxic and potentially affected by anthropic influences (Cu, pb, Zn, Cd, Cr, V, Ni, Co) of the superficial bed sediments of the St. George distributary which is the most sinuous and morphologically dynamic branch of the Danube River. Bed sediment samples were collected onboard of R.V. Istros, in June 2017. The dataset is useful to evaluate the distribution of the sediment along the fluvial channel, the present ecological state of the environment and, the effects of artificial intervention on the fluvial channel (the cutoff of the natural channels by navigational canals between 1984 and 1988). The data are presented as tabular format.