Indo-Gangetic Plain(redirected from Gangetic Plains)
an alluvial plain in India, Pakistan, and Bangladesh, between the Himalayas in the north and the Deccan plateau in the south, approximately 3,000 km long and 250-350 km wide.
The Indo-Gangetic Plain is an alpine piedmont depression, filled with fragmented products from the contiguous Himalayan slopes and covered with old and recent alluvia. The plain has a flat surface, gently descending from a divide (at a height of 270 m) to the Indus and Ganges deltas. The plained relief is broken by protrusions of crystalline rock in the west and scarps of river terraces with heights of up to 60 m divided by ravines. The climate of the eastern part (Ganges and Brahmaputra basins) is subequatorial monsoon. A tropical climate prevails in the western region (Indus basin). Monsoon circulation weakens toward the west, and there is an increase in aridity of climate. Over large areas of the Indo-Gangetic Plain, average temperatures in July range from 30° to 36°C. Temperatures in January are approximately 20°C (in the northwest, 12°C). Temperature drops to 0°C occur. Annual totals of precipitation decline from 1,500 mm in the southeast to 100-150 mm in the southwest.
The river system is dense. Rivers are deep-water, especially in the east. The largest rivers are the Indus with its tributary the Sutlej (known as the Panjnad in its lower course), which collects waters from the Jhelum, Chenab, Beas, and Ravi rivers (in Punjab); the Ganges with the Jamuna and its powerful left tributaries the Gomati, Ghaghara, and Gandak; and the Brahmaputra. The rivers are characterized by considerable fluctuations in water discharge. Runoffs are greatest in the summer as a result of the impact of monsoons and thawing of mountain snows; destructive flooding is frequent. Alluvial soils with various textures predominate.
An increase in climate aridity from east to west has an effect on the nature of terrain. Thick mangrove and evergreen forests grow in the east in the Ganges and Brahmaputra deltas. Deciduous forests and savannas are found in central plain areas; in the west there are salt marshes and sandy deserts. Practically nothing remains of natural vegetation in central areas and in the east. The Indo-Gangetic Plain is one of the oldest centers of world civilization. Terrains of cultivated savannas prevail (fields of rice, wheat, millet, corn, cotton, and other crops) with separate groves of palms and fruit trees. Two natural regions are identified within its limits, the arid Indus Valley and the moister Ganges Plain.
L. I. KURAKOVA