Patna
Topography

Patna is on the southern bank of the river Ganges. The total area of Patna is 250 km (97 sq mi). The municipal area constitutes 109.218 km (42.169 sq mi). The suburban area covers 140.782 km (54.356 sq mi). It has an average elevation of 53 m (174 ft). A characteristic feature of the geography of Patna is its confluence of major rivers.

During the British Raj, Patna was part of the Bengal Presidency. After Nalanda district was carved out of Patna district in 1976, Patna was purged of all hilly regions. It is an alluvial, flat expanse of land. The land in the district is too fertile and is almost entirely cultivated with no forest cover. Alluvial soil is ideal for cultivating rice, sugarcane, and other food grains. The area under cultivation is studded with mango orchards and bamboo groves. In the fields along the banks of river Ganges, weeds such as ammannia, citriculari, hygrophile and sesbania grow. But palmyra, date palm, and mango orchards are found near habitations. Dry stretches of shrubbery are sometimes seen in the villages far from the rivers. Trees commonly found are bel, siris, jack fruit, and the red cotton tree. Patna is unique in having four large rivers in its vicinity. It is the largest riverine city in the world. The topography of Patna city is saucer shaped as per Patna City Development Plan prepared in 2006. The bridge over the river Ganges named Mahatma Gandhi Setu is 5575m long. It is the longest river bridge in the India.

Patna comes under India's seismic zone-IV, indicating its vulnerability to major earthquakes, but earthquakes have not been common in recent history. Patna also falls in the risk zone for floods and cyclones.
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