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Investigating the Effects of Land Use Change on Subsurface, Surface and Atmospheric Branches of the Hydrologic Cycle in central Argentina
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  • Sujan Pal,
  • Francina Dominguez,
  • Pablo Bollatti,
  • Yi Yang,
  • Javier Alvarez,
  • Carlos Marcelo Garcia
Sujan Pal
University of Illinois at Urbana Champaign
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Francina Dominguez
University of Illinois at Urbana-Champaign-Department of Atmospheric Sciences

Corresponding Author:[email protected]

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Pablo Bollatti
Instituto National de Technologi ́a Agropecuaria
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Yi Yang
University of Illinois at Urbana-Champaign
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Javier Alvarez
Institute for Advanced Studies for Engineering and Technology (IDIT CONICET-UNC) and Exact, Physical and Natural Sciences College, National University of Córdoba, (FCEFyN - UNC)
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Carlos Marcelo Garcia
Universidad Nacional de Córdoba
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Since the 1970s, agricultural production in central Argentina has shifted away from perennial crops and grasses towards annual crops, largely soy. In this work we use observations and modeling to understand how this shift in land cover has affected the sub-surface, surface and atmospheric fluxes of moisture and energy in a flat agricultural area. We analyze the flux tower data from a paired site at Marcos Juarez in central Argentina during the period of the RELAMPAGO field campaign (2018-2019). When compared to perennial alfalfa, the observations over soy show lower evapotranspiration and specific humidity, higher sensible heat, higher outgoing shortwave radiation and soil temperature. Furthermore, water table depth is shallower below the soy than the alfalfa sites. To better understand the long-term temporal behavior from 1970s to present, the Noah-MP land surface model was calibrated at both soy and alfalfa sites based on RELAMPAGO data. Long-term simulation of the calibrated model suggests that ~95% of precipitation is evaporated in the alfalfa site with negligible recharge and runoff. In the case of soy, ET is about 68% of precipitation, leaving nearly 28% for recharge and 4% for runoff. Observed increases in streamflow and decreases in water table depth over time are likely linked to shifts in land cover. The changes in water table depth are enhanced in El Nino years. Furthermore, the partitioning of net radiation shifts from latent heat to sensible heat resulting in a 250% increase in Bowen ratio (from 0.2 to 0.7).
Nov 2021Published in Water Resources Research volume 57 issue 11. 10.1029/2021WR029704