Green and blue water demand from large-scale land acquisitions in Africa

Research output: Contribution to journalArticle

Abstract

In the last decade, more than 22 million ha of land have been contracted to large-scale land acquisitions in Africa, leading to increased pressures, competition, and conflicts over freshwater resources. Currently, 3% of contracted land is in production, for which we model site-specific water demands to indicate where freshwater appropriation might pose high socioenvironmental challenges. We use the dynamic global vegetation model Lund-Potsdam-Jena managed Land to simulate green (precipitation stored in soils and consumed by plants through evapotranspiration) and blue (extracted from rivers, lakes, aquifers, and dams) water demand and crop yields for seven irrigation scenarios, and compare these data with two baseline scenarios of staple crops representing previous water demand. We find that most land acquisitions are planted with crops that demand large volumes of water (>9,000 m3·ha-1) like sugarcane, jatropha, and eucalyptus, and that staple crops have lower water requirements (<7,000 m3·ha-1). Blue water demand varies with irrigation system, crop choice, and climate. Even if the most efficient irrigation systems were implemented, 18% of the land acquisitions, totaling 91,000 ha, would still require more than 50% of water from blue water sources. These hotspots indicate areas at risk for transgressing regional constraints for freshwater use as a result of overconsumption of blue water, where socioenvironmental systems might face increased conflicts and tensions over water resources.

Details

Authors
Organisations
External organisations
  • Federal Institute of Hydrology
  • Mediterranean Institute of marine and terrestrial Biodiversity and Ecology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Environmental Sciences related to Agriculture and Land-use

Keywords

  • Irrigation, Land grabbing, Lpjml, Water footprints, Water scarcity
Original languageEnglish
Pages (from-to)11471-11476
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number41
Publication statusPublished - 2016 Oct 11
Publication categoryResearch
Peer-reviewedYes