Palaeochannels evoke interest in view of its geological/ tectonic history, sediment domain and ground water prospects. Palaeochannel deposits are unconsolidated fluvial sediments, often coarse grained than adjoining flood plain deposits, and are valuable from ground water point of view. This was stated by Union Minister for State for Water Resources, River Development and Ganga Rejuvenation Prof. Sanwar Lal Jat while inaugurating a workshop on “Palaeochannels – Evolution and Groundwater Prospects” in New Delhi . He said because of better flushing mechanism in the groundwater system of palaeochannels due to coarser nature of sediments and fast recharge, the quality of groundwater is often better than the surrounding environment. The Minister said Palaeochannels of Late Quaternary (1- 0.5million year) period are of particular interest from ground water point of view. Optimum utilization of water resources warrants detailed understanding of ground water prospects of the palaeochannels, the Minister added.
With an objective to promote wide-ranging discussions on palaeochannels of India and collate available information and research outputs, Central Ground Water Board (CGWB) under Ministry of Water Resources, River Development and Ganga Rejuvenation organized the day long workshop. The workshop synthesized views, ideas, information through deliberations by pan-India experts, stakeholders etc. The focal points of the deliberations were geologic/ climatic/ tectonic reasons for disappearance of rivers, location, alignment and geometry of palaeochannels, sedimentological characteristics, ground water prospects and recharge potentials, developing priorities for future investigation and research.
CGWB has already organized three such workshops at Ahmadabad (July 2015), Allahabad (October 2015) and Jodhpur (March 2016). Discussion and deliberations of these workshops helped understanding the suitable methodologies to delineate the palaeochannels including synergetic and integrated use of multi-sensory satellite data, aerial photo, advance geophysical investigations, hydro-geochemical modeling, hydrogeological investigation, characterizing the sediments through drill cut samples etc. Substantial work has been done on those aspects by CGWB, State Ground Water Departments, Research Organizations, Academic Institutes and individual researchers.
Rivers, through ages, have been lifeline of civilizations in the World and Indian subcontinent as well. Besides the existing flowing rivers with active flood plains, there are remnants of old rivers which are identifiable. These remnants are called palaeochannels, and are characterized by relatively coarse clastics, in comparison to their floodplains over the banks.
Palaeochannels have been reported from different parts of India, covering the Indo-Gangetic plains as well as the central and peninsular India. Several ancient rivers now turned into Palaeochannels, which once supported civilization, agriculture and economic growth along its flood plains. Of all the reported palaeochannels, most widely researched, investigated and discussed are those located in the western and north-western parts of India, covering the states of Haryana, Rajasthan and Gujarat which is often linked to erstwhile mighty river Sarasvati.
It has always been intriguing to the researchers as to how the rivers migrate, disappear or get captured, leaving palaeochannels thereby. The palaeochannels reveal plethora of information about the history of the rivers, palaeoclimate, sedimentation process and the civilization along its banks, interwoven with its course and flood plains.