Linear Inversion of Fluvial Long Profiles to deduct the Upliftmet history:A case study of Siang Basin

Longitudinal river profiles record the uplift history of any tectonically active area. The tectonic forcing causes variation in the topography in the form of channel slope adjustments. The change in the gradient tends to migrate along the river profile at a definite rate. Thus, linear inverse modelling of the river profile can decrypt the spatiotemporal variability of the tectonic uplift rate. This approach relies on the analytical solution of the linear stream incision model. The inversion scheme is applied to the Siang Basin, a sub-basin of the tectonically active  Brahmaputra river system, to provide insight into the uplift history and paleo topography of the basin. The V-shaped Siang valley, located south of the Eastern Himalayan Syntaxis, undergoes a sudden change in slope descending from the Tsangpo gorge. The inversion is performed in the Siang Basin, assuming that the uniform tectonic uplift rate is time-independent but space-invariant. Inversion results reveal a temporal pattern of uplift acceleration between 1-2 Myr ago towards the present. The elevation profile indicates the occurrence of some prominent features that have rejuvenated the topography and increased erosion rates in the past. The base level plot also revealed a drastic fall in the base level since the past 2 Myrs. These results provide insights into the evolutionary history of the Siang Basin.