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The Impact of an Open Water-balance Assumption on the Understanding of the Factors that Control the Long-term Streamflow Components
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  • Andre Simões Ballarin,
  • Paulo Tarso Sanches Oliveira,
  • Bruno Ken Marchezepe,
  • Raquel Godoi,
  • Aline M Campos,
  • Fabrizio S Campos,
  • André Almagro,
  • Antonio Meira Neto
Andre Simões Ballarin
University of São Paulo

Corresponding Author:[email protected]

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Paulo Tarso Sanches Oliveira
Federal University of Mato Grosso do Sul
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Bruno Ken Marchezepe
University of São Paulo
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Raquel Godoi
University of São Paulo
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Aline M Campos
University of São Paulo
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Fabrizio S Campos
University of São Paulo
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André Almagro
Federal University of Mato Grosso do Sul
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Antonio Meira Neto
University of Arizona
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Abstract

Understanding how streamflow and its components, baseflow and quickflow, vary spatially according to climate and landscape characteristics is fundamental for dealing with different water-related issues. Analytical formulations have been proposed to investigate their long-term behavior and additional influencing factors, suggesting that they are mainly controlled by the aridity index ( Φ). Nevertheless, these studies assume the catchment as a closed water balance system, neglecting inter-catchment groundwater flow (IGF). This simplification makes the analysis of the long-term streamflow components and their main control mechanisms challenging, given that many catchments cannot be considered as closed hydraulic entities. Here, we assessed the controls of the mean-annual streamflow components and their behavior under an open water balance assumption, using observed data of 731 Brazilian catchments with diverse hydroclimatic conditions. Our results indicate that indeed streamflow components are primarily controlled by at the mean annual timescale. The consideration of an open water-balance significantly improved the performance of the functional forms to describe streamflow components while also elucidating the assessment of other influencing factors on the streamflow behavior. Land cover, groundwater, climate seasonality and topographic attributes appeared as the main control mechanisms beyond aridity. Overall, our study provides new insights of the main control mechanism of the streamflow behavior at the mean-annual scale, while shedding light on the importance of the open water-balance assumption for model development and water resources management.