Multi-decadal Evolution and North Atlantic Oscillation Influences on the Dynamics of the Danube Delta Shoreline

Abstract

VESPREMEANU-STROE, A.,CONSTANTINESCU, Ş., TĂTUI, F. and GIOSAN, L., 2007. Multi-decadal Evolution and North Atlantic Oscillation Influences on the Dynamics of the Danube Delta Shoreline. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 157 – 162. Gold Coast, Australia, ISSN 0749.0208 A comprehensive analysis of data collected over the last five decades on the Danube delta coast (topographic maps, satellite imagery, GPS surveys and beach profiles) revealed two different shoreline dynamics patterns: (1) high mobility during 1961-1979 interval with high retreating and; (2) advancing rates and low mobility afterwards (1979-2006). The divergence zones in the longshore sediment transport system experienced the highest rates of retreat (~20 m/yr and ~10 m/yr in the first/second time interval), whereas the shoreline advanced fastest along the coast of active lobes (i.e., Chilia and Sf. Gheorghe lobes). During the second interval the decrease of shoreline changes rates was similar for the erosive beaches (with 55-66%) and non-uniform for the accretionary coasts (20-61% for open beaches and 80% for the sheltered secondary deltas). Wind data analysis reveals a good connection between multi-decadal winter storm frequency along the Danube delta coast and negative NAO phases (r = -0.76). The results of the present study clearly show that shoreline changes at decadal time scales are also ultimately driven by the NAO which controls the storminess on the Danube delta coast. ADDITIONAL INDEX WORDS: shoreline retreat/advance, longshore sediment transport (LST), storms, multi-decadal climate variability, Black Sea