Geoinformation technologies for detecting spatial-temporal variability of suspended substances removal from the Danube delta

Abstract

The Danube Delta is one of the key natural systems in the northwestern part of the Black Sea, where riverine, lagoonal, and  marine waters interact, accompanied by sedimentation and resuspension of bottom material. Formed by river discharge, the Danube  plume spreads across the coastal zone and represents the largest plume in the Black Sea. Suspended particulate matter is a vital  component of this process, determining optical properties of water, transparency, the light regime, as well as the deposition and  transport conditions for certain pollutants. The objective of this study is to determine the spatiotemporal variability of total suspended  matter export from the Ukrainian part of the Danube Delta into the adjacent Black Sea waters using a multi-year series of satellite  observations. Satellite imagery from Landsat 8 and Landsat 9 over a five-year period was utilized. The concentration of total  suspended matter was determined using a methodology based on the red spectral band. Image composites were generated for each  calendar year. A conditional scale of export intensity was proposed to interpret the spatial structure of sediment transport. Significant  variability in the multi-year average area and configuration of the corresponding export zones was identified. The maximum width of  the export zone was recorded near the Bystre mouth. The scientific novelty lies in the spatial generalization of a multi-year series of  total suspended matter concentration indicators to characterize the geometric parameters of export zones rather than merely  individual concentration values. The obtained results can be applied to the remote sensing monitoring of the Danube plume and the  assessment of riverine suspended sediment transport impacts on Black Sea coastal waters.