Observations on a Late Medieval megaflood in the lower Mahanadi Valley, eastern India

Abstract

We present circumstantial evidence for a catastrophic flash flood possibly associated with regional tectonic instability in the Mahanadi Valley, eastern India during Late Medieval period. Luminescence dating of broken brick structures from a submerged temple in the lower reaches of the Mahanadi River constrains its construction to the early 16^th Century CE at Padmabati village in the Nayagarh district of the present-day Odisha State. Radiocarbon ages obtained from detrital charcoal and rootlets within soil units of a ∼1.6 m-deep pit excavated ∼400 m from the buried structures on an adjacent abandoned terrace/paleo-floodplain provide valuable insights into the paleo-events that may have occurred at the site. Geochemical similarities between the temple bricks and the terrace soil confirm that the temple remains are in situ. Geological and chronological evidence together suggest the occurrence of a catastrophic flash flood, possibly resulting from regional tectonic instability in the Mahanadi Basin during or after late 16^th Century CE, which led to temple submergence at Padmabati. The inferred period of temple construction coincides with the rule of the Gajapati dynasty in medieval Odisha, thereby marking it as the youngest known medieval-era brick temple reported from the Indian subcontinent.