Tectonic control on alluvial fans, piedmont streams and Ganga River in western Ganga Plain (India) using satellite remote sensing data

摘要

The present study pertains to a segment of the western Ganga Plain drained by the River Ganga and its tributaries in the area between Haridwar, Roorkee and Bijnor. Various geomorphic surfaces were identified on the basis of satellite remote sensing data aided by field investigations. The dominant geomorphic surfaces identified are megafan surface (MF), older flood plain (T-1), piedmont fan surfaces, viz. PF2 (older) and PF1 (younger), and active flood plain (T-0). The disposition of these geomorphic surfaces and the trends of streams are interrelated and tectonically controlled. Upland terrace surface (T-2), which is the oldest depositional surface of Ganga Plain, is not exposed in this area and it is the reworked MF on which all other surfaces are superposed. The large sized coalescing fans of PF2 and superposed PF1 evolved by the deposition of sediments derived from the rising Himalayan and Siwalik ranges. The narrow widths of T-1 and T-0 terrace surfaces of the Ganga and its tributaries are the result of deep incision by these rivers owing to their tectonic control. There are evidences of progressive lateral migrations of the Ganga channel to both directions. The study also indicates that presently the processes of deposition are active mainly on T-0 and upper part of the PF1.