Holocene evolution and Anthropocene destruction of the Krishna Delta on the east coast of India: Delta lobe shifts, human impacts, and sea-level history

Kakani Nageswara Rao*, Yoshiki Saito, K. Ch V. Naga Kumar, Sumiko Kubo, Shilpa Pandey, Zhen Li, G. Demudu, A. S. Rajawat

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The Holocene evolution of the Krishna Delta was inferred using landform characteristics and 11 sediment cores with 59 Accelerator Mass Spectrometry 14C dates. The landform assemblages in a 5880 km2 area of the Krishna Delta indicate an upper (landward) river-built fluvial plain and a lower (seaward) marine-built beach-ridge plain. Holocene sediment unconformably overlying a Pleistocene basement consists of 11 sedimentary facies, mainly shallowing-upward and deltaic succession. Sea level indicators such as the basal mangrove peat layers above the Pleistocene basement and the foreshore sediments indicate that the sea level rose from −9 m to −3 m during 8.3–6.3 cal ky BP, and stabilised at the present level around 5 cal ky BP. The 3539 km2 area of the Krishna Delta beach-ridge plain developed in five major stages during the last 6 cal ky, with distinct lateral and seaward migration of delta lobes (depocentre shifts). Delta progradation accelerated in the last 500 years, forming an out-building lobate delta. However, predominant erosion along the sediment-starved coast during the past five decades, due to impoundment of riverine inputs at the burgeoning upstream dams, has pushed the Krishna Delta into a persistent destruction phase.

Original languageEnglish
Article number106229
JournalMarine Geology
Volume427
DOIs
Publication statusPublished - 2020 Sep

Keywords

  • Beach-ridge plain
  • Coastal erosion
  • Delta lobes
  • Pleistocene–Holocene unconformity
  • Sedimentary facies

ASJC Scopus subject areas

  • Oceanography
  • Geology
  • Geochemistry and Petrology

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