Alakhnanda–Bhagirathi River System

India has large numbers of rivers where human civilizations have flourished in the past. There has been a change in the landform caused due to interplay of climate overtime, which led to distribution of human settlement. The Himalayas is the birthplace of many important rivers which are perennial in nature. There are three main rivers and their tributeries in Himalayas: Brahmaputra, Ganges and Indus, which are responsible for shaping up of the Himalayan landforms and responsible for formation of Indo-Brahmaputra-Gangetic Alluvial Plain. The Ganges is a very long river in the Indian subcontinent with many tributaries, and it occupies the central part of the three main river systems. The Ganges and its tributaries are a typical example of antecedent rivers, which are going across the Himalayan range through primary geologic structures and post-date both metamorphism and development of collision-related structures. The river system has originated within the upper Higher Himalayan Crystallines (HHC); however, a few tributaries have their origin from Tethyan Sedimentary Zone close to Indo-China border. These tributaries cross Malari Fault or Martoli Fault which is also known as the South Tibetan Detachment System (STDS). This fault demarcates the boundary between Tethyan Sedimentary Zone and upper Higher Himalayan Crystallines (Vaikrita Group) and also seldom defines as Dar-Martoli Fault.