Agricultural expansion raises groundwater and increases flooding in the South American plains

• 成果类型: Article
• 署名作者: Houspanossian, Javier; Gimenez, Raul; Whitworth-Hulse, Juan I.; Nosetto, Marcelo D.; Tych, Wlodek; Atkinson, Peter M.; Rufino, Mariana C.; Jobbagy, Esteban G.
• 署名单位: Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Universidad Nacional de San Luis; Lancaster University; Technical University of Munich
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-11691
• DOI: 10.1126/science.add5462
• 发表日期: 2023-06-30
• 页码: 1344-1348
• 关键词: land-use; water; soil; variability; depletion; salinity; drainage; pampas

摘要

Regional effects of farming on hydrology are associated mostly with irrigation. In this work, we show how rainfed agriculture can also leave large-scale imprints. The extent and speed of farming expansion across the South American plains over the past four decades provide an unprecedented case of the effects of rainfed farming on hydrology. Remote sensing analysis shows that as annual crops replaced native vegetation and pastures, floods gradually doubled their coverage, increasing their sensitivity to precipitation. Groundwater shifted from deep (12 to 6 meters) to shallow (4 to 0 meters) states, reducing drawdown levels. Field studies and simulations suggest that declining rooting depths and evapotranspiration in croplands are the causes of this hydrological transformation. These findings show the escalating flooding risks associated with rainfed agriculture expansion at subcontinental and decadal scales.