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Updated: Jul 25, 2025

Capturing Flow-weighted Water and Suspended Particulates from Agricultural Canals During Drainage Events
Published on: November 7, 2017
Agricultural expansion raises groundwater and increases flooding in the South American plains
Javier Houspanossian1,2, Raul Giménez1,2, Juan I Whitworth-Hulse1
1Grupo de Estudios Ambientales, CONICET, San Luis, Argentina.
Abstract:
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.
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