Articles | Volume 20, issue 6
Review article
07 Jun 2016
Review article |  | 07 Jun 2016

A review of green- and blue-water resources and their trade-offs for future agricultural production in the Amazon Basin: what could irrigated agriculture mean for Amazonia?

Michael J. Lathuillière, Michael T. Coe, and Mark S. Johnson

Abstract. The Amazon Basin is a region of global importance for the carbon and hydrological cycles, a biodiversity hotspot, and a potential centre for future economic development. The region is also a major source of water vapour recycled into continental precipitation through evapotranspiration processes. This review applies an ecohydrological approach to Amazonia's water cycle by looking at contributions of water resources in the context of future agricultural production. At present, agriculture in the region is primarily rain-fed and relies almost exclusively on green-water resources (soil moisture regenerated by precipitation). Future agricultural development, however, will likely follow pathways that include irrigation from blue-water sources (surface water and groundwater) as insurance from variability in precipitation. In this review, we first provide an updated summary of the green–blue ecohydrological framework before describing past trends in Amazonia's water resources within the context of land use and land cover change. We then describe green- and blue-water trade-offs in light of future agricultural production and potential irrigation to assess costs and benefits to terrestrial ecosystems, particularly land and biodiversity protection, and regional precipitation recycling. Management of green water is needed, particularly at the agricultural frontier located in the headwaters of major tributaries to the Amazon River, and home to key downstream blue-water users and ecosystem services, including domestic and industrial users, as well as aquatic ecosystems.

Short summary
We apply the green- and blue-water perspective to Amazonia's water resources to highlight trade-offs that may arise with future land use change. We question how future irrigation may supply additional water vapour to the atmosphere with growing agricultural production. Maintaining precipitation recycling could prevent degradation of rainfall-dependent terrestrial ecosystems and has the potential to minimize blue-water trade-offs between up- and downstream water users within the Amazon Basin.