The Ganges & Brahmaputra Delta

Course

The upper phase of the river Ganges begins at the confluence of the Bhagirathi and Alaknanda rivers in the town of Devprayag in the Garhwal division of the Indian state of Uttarakhand. The Bhagirathi is considered to be the source in Hindu culture and mythology, although the Alaknanda is longer, and therefore, hydrologically the source stream. The headwaters of the Alakananda are formed by snow melt from peaks such as Nanda Devi, Trisul, and Kamet. The Bhagirathi rises at the foot of Gangotri Glacier at Gomukh, at an elevation of 4,356 m (14,291 ft) and was mythologically referred to as residing in the matted locks of Shiva; symbolically Tapovan, which is a meadow of ethereal beauty at the feet of Mount Shivling, just 5 km (3.1 mi) away.

Hydrology

Major left-bank tributaries include the Gomti River, Ghaghara River, Gandaki River and Kosi River; major right-bank tributaries include the Yamuna River, Son River, Punpun and Damodar. The hydrology of the Ganges River is very complicated, especially in the Ganges Delta region. One result is different ways to determine the river's length, its discharge, and the size of its drainage basin.

The name Ganges is used for the river between the confluence of the Bhagirathi and Alaknanda rivers, in the Himalayas, and the first bifurcation of the river, near the Farakka Barrage and the India-Bangladesh Border. The length of the Ganges is frequently said to be slightly over 2,600 km (1,600 mi) long, about 2,601 km (1,616 mi), 2,525 km (1,569 mi) or 2,650 km (1,650 mi).

History

During the mature phase of the Indus Valley Civilisation, the Ganges was not the primary center of urban life, as larger settlements were concentrated in the Indus River basin. However, due to climate shifts and the drying of the Saraswati River around 1900 BCE, populations began a gradual eastward migration toward the more humid Indo-Gangetic Plain. This period marked the transition from Bronze Age urbanism to the "Ganga Culture," characterized by the Painted Grey Ware (PGW) settlements.

By the late Vedic period, the Ganges became the central sacred geography of South Asia. The river facilitated the rise of the Mahajanapadas, particularly Magadha. The river served as a vital trade artery for the Mauryan Empire.

Ecology and environment

Human development, mostly agriculture, has replaced nearly all of the original natural vegetation of the Ganges basin. More than 95% of the upper Gangetic Plain has been degraded or converted to agriculture or urban areas. Only one large block of relatively intact habitat remains, running along the Himalayan foothills and including Rajaji National Park, Jim Corbett National Park, and Dudhwa National Park.

Geography

The upper reaches of the Brahmaputra River, known as the Yarlung Tsangpo from the Tibetan language, originate on the Angsi Glacier, near Mount Kailash, located on the northern side of the Himalayas in Burang County of Tibet. The source of the river was earlier thought to be on the Chemayungdung glacier, which covers the slopes of the Himalayas about 60 mi (97 km) southeast of Lake Manasarovar in southwestern Tibet.

From its source, the river runs for nearly 1,100 km (680 mi) in a generally easterly direction between the main range of the Himalayas to the south and the Kailas Range to the north.

In Tibet, the Tsangpo receives a number of tributaries.

History

The Kachari group called the river "Dilao", "Tilao". Early Greek accounts of Curtius and Strabo give its name as Dyardanes (Ancient greek Δυαρδάνης) and Oidanes. In the past, the course of the lower Brahmaputra was different and passed through the Jamalpur and Mymensingh districts. Some water still flows through that course, now called the Old Brahmaputra, as a distributary of the main channel.

A question about the river system in Bangladesh is when and why the Brahmaputra changed its main course, at the site of the Jamuna and the "Old Brahmaputra" fork that can be seen by comparing modern maps to historic maps before the 1800s.