Teesta River - Climate and Tectonics of Teesta River

Climate and Tectonics of Teesta River

The Teesta river has preserved good imprints of climatic and tectonics along its valleys and catchments. The significant fluvial landscape of the Teesta river has been described by few workers, e.g., Archarya, Mukhopadhyay, Malay Mukul, Ingocha Meetei Lukram. Not many international papers have been published about the Teesta river. The recent paper of Ingocha Meetei Lukram suggested that climate change, particularly on a millennial to multi-millennial scale, during late Quaternary had a strong system-wide influence on sediment production, transport and deposition in the Teesta river system (Meetei et al., 2007)

The interrelationship between climate, erosion, deposition and tectonic activities is not properly understood to date. However, it appears that major alluviation and incision events could be ascribed to the factors associated with climatic processes such as strengthening or weakening of monsoonal precipitation and related fluvial discharge. Tectonic activity affects sediment fluxes and is responsible for the insetting of younger terraces/fanlobes into the older terraces/fanlobes. During seismic events, landslide activity along the slopes of river valleys influences sediment delivery into the valleys, causing the effects of tectonics to be intricately coupled with that of climate (Meetei et al. 2007).

The terraces and floodplains, valley-side slopes and landslide slopes, alluvial cones of different generations, kettle-shaped depressions, sickle-shaped ranges, leveled plains, undulating plains and deeply dissected valleys, and glacial and periglacial deposits are some of the geomorphological features observed in the Teesta river basin in Sikkim (Mukhopadhayay, 1982). Three prominent knick points have been observed along the Teesta river profiles which correspond to the zones of tectonic discontinuities, the important ones being the MCT and MBT (e.g. Seeber and Gornitz, 1983). From the recent studies of Mukul (2000) and Mukul et al. (2007), it is proved that the southern part of the frontal wedge near the foothill zone is tectonically active along with the formation of NKT, SKT and MFT structures within the sub-Himalaya in the Teesta basin.