Control on the evolution of badlands and their erosional dynamics, Central Narmada Basin, India

Abstract

The Central Narmada Basin (CNB) in India is a seismically active region comprising the ENE-WSW trending Narmada-Son Lineament (NSL) bounded by the Narmada North Fault (NNF) and the Narmada South Fault (NSF). Despite the multiple badland zones in the Indian subcontinent, the Sher river valley badland of the CNB is yet to be adequately explored in terms of in-depth research on the evolution of badlands associated with intraplate zones. Using the Cartosat-1 digital elevation model, field investigation and morphometric analysis of the upper Sher river valley zone near the NSF, this study can help to understand the morphogenesis of the badlands in relation to tectonics or climate and describe the erosional history. Litho-stratigraphically, the bottom ∼ 7 m thick Baneta Formation is overlain by the 12–14 m thick Hirdepur Formation. According to peculiar litho-units chronology, the ravine’s expansion began post-LGM. Fractures filled with muddy carbonate material strike in a mean direction of 99°±7°. Moreover, the azimuthal direction of the first-order ravines indicates a mean direction of 81°±3°. Consequently, the direction of the conjugate fracture and the ravines corresponded to the ENE-WSW, suggesting that the basin is primarily controlled by movements along the boundary faults. The morphometric characteristics indicate relative movement along the NSF, which would lead to the incision of the Sher river and the formation of badlands. This also implies that the badlands were mostly tectonically controlled or formed by the reactivation of the NSF. A coarser badland landscape is characterized by an abundance of sandy silt to silty sand particles associated with badland surfaces. In addition, the smectite-rich swelling clay helps to promote instability and enhancement of gully surfaces. The average sediment yield of the seven sub-catchments of the Sher river valley varies from 1230 to 321 t/km2/yr, which is significantly lower than that of the Yamuna badlands.