The total area of Tianjin is 11,000 square km. Its territory is 900 km in circumference and the length of its coastline is 153 km. The topography of Tianjin with mountainous areas, hilly land and the plain is high in northwest and low in southeast. The area of the plain makes up 94 percent of the total. Rivers passing the city include the main stream of the Haihe River, the South and North Canals of the Grand Canal, Ziya Daqing, Yongding, Chaobai and Jiyun rivers, constituting a rich hydrographic net in Tianjin.