Coastal Research Group in the frame of CRMD – overview of research activities

The Coastal Research Group in the frame of CRMD Research Centre undertakes various research activities in Danube Delta, on the Romanian Black Sea Coast and along the Danube river valley related to coastal morphodynamics, coastal hazards, geoarchaeology, large-scale evolution of coastal environment, GIS and remote sensing analyses applied in coastal geomorphology and coastal system integrated management. The general aim of our group is to get a well-grounded understanding of the coastal processes and associated coastal behaviour at multiple spatial and temporal scales

Flood deposition and storm removal of sediments in front of a deltaic wave-influenced river mouth

International audienceFloods and storms are common phenomena at river mouths with some degree of wave influence. They can have a considerable impact on river-mouth sedimentation and morphological change, although studies elucidating this relationship are relatively rare. The present paper analyzes annual bathymetric changes based on surveys at the mouth of the Sfantu Gheorghe branch of the Danube river delta between 2004 and 2018, and relates bed changes with measured river freshwater and solid discharges, and wave height data. We found a strong inter-annual variability of morphological volume change which ranged from 5.23 x 10(6) m(3) deposited during the extreme flood of 2006 (maximum discharge of similar to 4000 m(3)/s), to -6.88 x 10(6) m(3) removed during the stormy year of 2012 (wave heights > 6 m). The sediment budget of the river-mouth area is modulated by the inter-annual variability of storms and floods, and can be estimated by the newly proposed Flood/Storm index based on river water or sediment discharge and wave height proxies (R-2 = 0.84). A selection of discharge and wave thresholds were simulated with Mike 21/3 by DHI (Danish Hydraulic Institute), a coupled hydrodynamic and wave model to characterize circulation and the applied bed shear stresses at this complex river-mouth sedimentary system. The model simulates 3D jet and plume hydrodynamics during floods, and the longshore current and wave dissipation during storms. Finally, field data are integrated with the Mike 21/3 model results to derive a conceptual hydro-morphodynamic model of an asymmetric wave influenced river-mouth bar during the two antagonistic phases of flood-driven and storm-driven dynamics. During floods, the importance of current circulation and counter- plume currents in trapping sediments in a seaward-thinning depositional wedge is discussed. During storms, the sediment deposited during floods is removed by the high bed shear stresses generated by waves and currents

The evolution of Sf. Gheorghe (Danube) asymmetric deltaic lobe

The wave asymmetric Sf. Gheorghe lobe is the only active in the Danube delta where river mouth bar (and the associated barrier islands and spits) continuously deployed a cyclic development for almost two millennia. During first stage, the Sf. Gheorghe distributary had a small discharge (with an order of magnitude lower than present) which after that experienced a rapid increase in consequence of the successive avulsions of Împuţita (southern distributary of Sulina arm) and Dunavăţ distributaries. Our morphological analyses together with the newly obtained chronology, revealed the multiple ridgesets structure of Sf. Gheorghe deltaic lobe. In fact, all ridgesets (10) follow a common morphodynamic pattern characterized by the cyclic succession of three stages: i) subaqueous mouth bar development, ii) barrier island emergence, iii) barrier spit phase with several secondary spits derived from an updrift trunk ridge. The size of each ridgeset increased exponentially with every new cycle due to the constant lengthening of the coastline as the downdrift side of the lobe advances seaward through a series of progressively larger similar quadrilaterals, yielding to a constant enlargment of the delta front size. </p

Meteorological information from Romanian newspapers of the 19th century (ROMETNEWS19)

The dataset contains meteorological information from the period 1880-1900 extracted from three Romanian newspapers (România Liberă, Gazeta de Transilvania and Foaia Poporului). Each entry represents a meteorological event, with its metadata and characteristics (date, location, category, impact, validation). Validation consisted in checking the consistency of the newspaper reports with meteorological observations from weather stations