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Braiding and Planform Pattern of Ganga

2022; Springer International Publishing; Linguagem: Inglês

10.1007/978-3-030-77572-8_2

2366-8865

Zulfequar Ahmad, Mohammad Zakwan, Pradeep Kumar Garg,

Hydrology and Watershed Management Studies

Planform index, sinuosity ratio and braiding ratio are commonly used for defining the planform pattern of a river. The present chapter explores the spatial variation in the sinuosity ratio from Devprayag to Farakka, thereby identifying highly sinuous reaches of Ganga River. High sinuosity ratio represents chances of channel migration and landscape changes. In this regard, the present chapter aims to analyse the planform pattern and sinuosity of Ganga River. The entire studied reach was subdivided into 37 reaches. For the present study, toposheets with a scale of 1:50,000 were obtained from the Survey of India, and remote sensing digital data were obtained from GLCF website, USGS website and NRSC Hyderabad. From Devprayag to Farakka the maximum, minimum and average sinuosity ratios are of the order of 2.2, 1.1 and 1.38 for the years 1970, 1980, 1990, 2000 and 2010, respectively. Sinuosity ratios in the reaches 200–250 km, 600–700 km, 800–900 km and 1750–1824 km are relatively higher than the other reaches. As the average value of the sinuosity ratio for the whole reach of the river was 1.38; therefore, the Ganga shall be considered as sinuous river except in these reaches. Further, it may be concluded that except the meanders M-1(d/s Sultanganj), M-2 (Upstream of Sultanganj) and M-3 (Munger), all other meanders are stable. At the meanders M-1, M-2 and M-3, the river has left the meandering route and followed a relatively straight path over the years. The analysis of results reveals that Ganga River is prominently braided downstream of Haridwar, Garhmukteshwar, Ramghat (downstream of Narora), Kachlabridge, upstream of Farrukhabad, upstream of Allahabad, Balia, Raghopur and Krusela. High braiding in the Ganga River downstream of the Haridwar, upstream of Allahabad, Krusela, etc. was primarily due to aggradation, which occurs as the river was found to be incompetent to transport the sediment load that it brings or the tributaries were bringing from the relatively steep reach.