Multi-Proxy Records of Late Holocene Flood Events From the Lower Reaches of the Narmada River, Western India

Abstract

Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish a record of rhythmic cycles of sediment facies that represent floods during the late Holocene. The south-west Indian monsoon strongly influences the study area, and heavy rainfall or cyclones which originate from either the Bay of Bengal or the Arabian Sea, also affect the region. Optically stimulated luminescence dating places the 8 m thick sediment sequence in the climate transition phase which ranges from the Medieval Warm Period to the Little Ice Age. Multi-proxy analyses including high-resolution granulometry, magnetic susceptibility, ferromagnetic mineral concentration, facies major oxide geochemistry, and micro-fossil records (from two sedimentary units) are used to study these late Holocene flood events. The latter are characterised by multiple sediment facies, depositional events, changes in channel morphology, and distinctive flood signatures. Integration of these records enables to identify two distinct aggradations viz. phase I and phase II, as well as a relative change in channel morphology. The study describes 11 flooding events and their imprints over multi-proxy records. Historic documents and instrumental records from the town of Bharuch referring to floods, movement of channel sand, channel shallowing, and the dysfunction of the ancient port of Bharuch further validate the inferences drawn from the sedimentary sequence. The study exemplifies the need to use high resolution and multi-proxy studies to interpret paleoflood records and climate signatures in order to build archives of monsoonal rivers.

Revisit the Medieval Warm Period and Little Ice Age in Proxy Records from Zemu Glacier Sediments, Eastern Himalaya: Vegetation and Climate Reconstruction

“…The reconstructed climatic variables were further compared to the environmental geomagnetic data of the profile sediments. The study of the mineral magnetic properties of sediments has become an increasingly useful tool to understand the input of sediment flux in different depositional environments containing iron mineral particles [89][90][91][92][93]. The technique is useful for reconstructing climate and environment because the mineral magnetic characteristics of sediments are sensitive to variations in climate, transport medium, and environmental conditions [90,91,[94][95][96].…”

Remote sensing for monitoring the impacts of agroforestry practices and precipitation changes in particle size export trends

“…Rainfed annual crops are considered among the agricultural practices that influence soil erosion, particularly during the period when the soil surface of croplands has no plant cover protection (Lizaga et al, 2020). In this climate and land use distribution context, the importance of exceptional rainstorms has been highlighted and they have been found to be responsible for major geomorphological changes and the export of riverbed fine sediment to downstream water bodies (Nadal-Romero et al, 2012;Serrano-Notivoli et al, 2017;Sukumaran et al, 2021;Wu et al, 2021;Ramos et al, 2022). In the last decades, most cultivated fields with a high risk of erosion located at the headwaters in Mediterranean mountains have been abandoned and naturally replaced by vegetation or afforested.…”