Tectonic implication of drainage set-up in the Sub-Himalaya: A case study of Papumpare district, Arunachal Himalaya, India

The channel forms and landforms have been studied in relation to the neotectonics of the area. The watersheds exhibit their structurally controlled nature, with drainages following tectonic alignments. Rivers/streams experienced compressed meandering, narrowing, widening and deflection of channels. Longitudinal profiles of river/stream channels exhibit knick points. Unpaired terraces are observed at higher levels. Factors like the unconsolidated Siwalik rocks, tectonic instability along faults and high rainfall with the advent of the Holocene, led to the development of the present-day drainage set-up. A tectonic model is proposed for development of tectonic geomorphology of the area influenced by ultra-tremor to low magnitude earthquakes in seismically very active northeastern India, as moderate to big earthquakes (M ≥ 6.0) are scarce in this region.