G-44 The Filyos river has a length of 228 km and a drainage area of 13 000 km2. Near Gökçebey district, Gerede Streams, Araç Streams, Devrek Streams, Yenice Streams and Soğanlı Streams combine to form the Filyos River. Filyos River is the fourth largest river of the Southern Black Sea Region after Kızılırmak, Yeşilırmak and Sakarya. However, it is the first and largest in terms of sediment load discharged into the sea due to the absence of any dam on it. The Filyos River delta is a wave-dominated, narrow and long sediment stack because the coastal region is very energetic and prevents delta progression. The sediments of all beaches along the coast are supplied by the river itself and the delta. The last 10 km of the river is in a flat and low channel. For this reason, flood barriers made of gravel were built along the channel to prevent any flooding.