Cover Image

An illustration of the role of variable subsidence rate on surface morphology across the Ganga Plain, downstream of the Himalayas. How major rivers draining the Ganga Plain respond to changes in external forcing (sediment flux, discharge) is related to the subsidence rate of the underlying basin. Where changes in external forcing leads to a reduction in the fan slope between t0 (black solid line) and t1 (red solid line), this can be accommodated with net aggradation where subsidence rates are high (1) but requires incision into the fan apex where subsidence rates are lower (2).

The paper explores the probable controls on fluvial and surface morphology across the Ganga Plain through an analysis of floodplain and channel topography, basin subsidence rates, sediment grain size data and sediment supply from the main river systems that traverse the Plain. The authors propose that higher subsidence rates are responsible for a deeper basin in the east Ganga Plain with perched, low gradient river systems that are relatively insensitive to climatically driven changes in base-level. In contrast, the lower subsidence rates in the west are associated with a higher elevation basin topography, and entrenched river systems recording climatically induced lowering of river base-levels during the Holocene. See article by Dingle and others, p. 778–812.