Fluvial landscapes of the Harappan Civilization

Liviu Giosan*, Peter D. Clift, Mark G. Macklin, Dorian Q. Fuller, Stefan Constantinescu, Julie A. Durcan, Thomas Stevens, Geoffrey Alastair Thomas Duller, Ali R. Tabrez, Kavita Gangal, Ronojoy Adhikari, Anwar Alizai, Florin Filip, Sam VanLaningham, James P. M. Syvitski

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

250 Citations (Scopus)

Abstract

The collapse of the Bronze Age Harappan, one of the earliest urban civilizations, remains an enigma. Urbanism flourished in the western region of the Indo-Gangetic Plain for approximately 600 y, but since approximately 3,900 y ago, the total settled area and settlement sizes declined, many sites were abandoned, and a significant shift in site numbers and density towards the east is recorded. We report morphologic and chronologic evidence indicating that fluvial landscapes in Harappan territory became remarkably stable during the late Holocene as aridification intensified in the region after approximately 5,000 BP. Upstream on the alluvial plain, the large Himalayan rivers in Punjab stopped incising, while downstream, sedimentation slowed on the distinctive mega-fluvial ridge, which the Indus built in Sindh. This fluvial quiescence suggests a gradual decrease in flood intensity that probably stimulated intensive agriculture initially and encouraged urbanization around 4,500 BP. However, further decline in monsoon precipitation led to conditions adverse to both inundation- and rain-based farming. Contrary to earlier assumptions that a large glacier-fed Himalayan river, identified by some with the mythical Sarasvati, watered the Harappan heartland on the interfluve between the Indus and Ganges basins, we show that only monsoonal-fed rivers were active there during the Holocene. As the monsoon weakened, monsoonal rivers gradually dried or became seasonal, affecting habitability along their courses. Hydroclimatic stress increased the vulnerability of agricultural production supporting Harappan urbanism, leading to settlement downsizing, diversification of crops, and a drastic increase in settlements in the moister monsoon regions of the upper Punjab, Haryana, and Uttar Pradesh.
Original languageEnglish
Pages (from-to)E1688-E1694
Number of pages7
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number26
DOIs
Publication statusPublished - 26 Jun 2012

Keywords

  • HISTORY
  • archaeology
  • droughts
  • INDUS VALLEY
  • DYNAMICS
  • climate change
  • Indus Valley
  • MONSOON
  • MOISTURE EVOLUTION
  • ALLUVIAL FANS
  • floods
  • CLIMATE-CHANGE
  • HOLOCENE
  • INDIA
  • CENTRAL-ASIA
  • Archaeology
  • Climate change
  • Droughts
  • Indus valley
  • Climate
  • Urban Population
  • Floods
  • Civilization
  • Geologic Sediments
  • History, Ancient
  • Asia

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