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The Indo-Gangetic Plain, also known as Indus-Ganga and the North Indian River Plain, is a 255 million hectare (630 million acre) fertile plain encompassing most of northern and eastern India, the eastern parts of Pakistan, and virtually all of Bangladesh. The region is named after the Indus and the Ganga, and encompasses a number of large urban areas. The Indus-Ganga plain is bound on the north by the Himalayas which feed its numerous rivers and are the source of the fertile alluvium deposited across the region by the two river systems. The southern edge of the plain is marked by the Chota Nagpur Plateau. On the west rises the Iranian Plateau. ==Divisions== Some geographers subdivide the Indo-Gangetic Plain into several parts: the Indus Valley Plain, the Punjab Plain, the Haryana Plain, and the middle and lower Ganges Plains. These regional distinctions are based primarily on the availability of water. By another definition, the Indus-Ganga Plain is divided into two drainage basins by the Delhi Ridge; the western part consists of the Punjab Plain and the Haryana Plain, and the eastern part consists of the Ganga–Brahmaputra drainage systems. This divide is only 300 metres above sea level, causing the perception that the Indus-Ganga Plain appears to be continuous between the two drainage basins. Both the Punjab and Haryana plains are irrigated with water from the Ravi, Beas, and Sutlej rivers. The irrigation projects in progress on these rivers have led to a decrease in the flow of water, which reaches the lower drainage areas in the state of Punjab in India and the Indus Valley in Pakistan. The benefits that the increased irrigation has brought to Haryana farmers are controversial due to the effects that irrigation has had on agricultural life in the Punjab areas of both India and Pakistan. The middle Ganga plain extends from the Yamuna River in the west to the state of West Bengal in the east. The lower Ganges plain and the Assam Valley are more verdant than the middle Ganga plain. The lower Ganga is centered in West Bengal, from which it flows into Bangladesh. After joining the Jamuna, a distributary of Brahmaputra, both rivers form the Ganges Delta. The Brahmaputra rises in Tibet as the Yarlung Zangbo River and flows through Arunachal Pradesh and Assam, before crossing into Bangladesh. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Indo-Gangetic Plain」の詳細全文を読む スポンサード リンク
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