a river in southeastern Spain. The Segura is 341 km long and drains an area of 16,200 sq km. It originates in the Sierra de Segura, part of the Andalusian mountain system, at an elevation of approximately 1,500 m. It flows primarily to the east, through the mountains and across the Murcian plain, and empties into the Mediterranean Sea. There are flash floods in the winter and autumn; in the summer the river is shallow. The mean flow rate at the point where the Segura flows out of the mountains is 21 cu m per sec; the rate decreases farther downstream because of extensive irrigation. There are reservoirs and hydroelectric power plants on the river. The Segura is not navigable. The city of Murcia is located on the Segura.