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

Research output: Contribution to journalArticle

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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