Sedimentary records of palaeohydrological variability during the Late Holocene in the Lower Narmada Basin, western India

Abstract It is important to understand the long‐term climate variability for better insight into the climate change scenario. The monsoon‐fed alluvial rivers of western India provide potential archives for palaeohydrological change. Here we attempt to reconstruct the palaeohydrological variability from the terrace sediments along the Orsang River, a tributary of the Narmada River during the last 1500 years using multiple proxies. The results reveal three distinct depositional phases: I. >1358–1003 cal yr. BP, II. 1003–600 cal yr. BP and III. 600–191 cal yr. BP in the Orsang Basin. The depositional phases I and III correlate with significant global cold and arid climatic phases i.e. DACP and LIA respectively whereas phase II represents the MWP. The high discharge conditions in the Narmada River during the MWP resulted in back flooding and slackwater sedimentation in the Orsang River especially ~704 cal yr. BP as suggested by the Sr‐Nd isotopic ratios and high AOM. A significant influx of terrestrial organic matter related to high erosion and runoff due to intense precipitation events prior to 1358, ~1003 and ~601 cal yr. BP in the Orsang River (tributary) marks the climatic transitions. The terrace deposits in the Orsang tributary have recorded the high‐magnitude flood events in the Narmada River during wet periods (MWP), and in the tributaries during dry periods, (DACP and LIA). The study demonstrates that tributary terrace sequences are valuable archives for palaeoflood inferences and the use of multiple proxies helps in demarcating local versus regional hydrological events. The inferences underscore the sensitivity of monsoon‐dominated fluvial systems to climatic excursions. The regional heterogeneity highlights that climatic shifts during the Late Holocene were not globally uniform. While periods of a stronger Indian Summer Monsoon matched those in Southeast Asia, they contrasted with trends in the Eastern Mediterranean and the Middle East.