<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "https://jats.nlm.nih.gov/nlm-dtd/publishing/3.0/journalpublishing3.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" specific-use="SMUR" dtd-version="3.0" xml:lang="en">
<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-1363</article-id>
<title-group>
<article-title>Same Streamflow, Different Water Stories: The Hidden Impacts of Streamflow-Only Calibration in Distributed Hydrological Modeling</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Vásquez</surname>
<given-names>Nicolás A.</given-names>
<ext-link>https://orcid.org/0000-0002-4651-8935</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Mendoza</surname>
<given-names>Pablo A.</given-names>
<ext-link>https://orcid.org/0000-0002-0263-9698</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Knoben</surname>
<given-names>Wouter</given-names>
<ext-link>https://orcid.org/0000-0001-8301-3787</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Clark</surname>
<given-names>Martyn</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Stadnyk</surname>
<given-names>Tricia</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Mizukami</surname>
<given-names>Naoki</given-names>
<ext-link>https://orcid.org/0000-0002-0893-5869</ext-link>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Civil Engineering, Universidad de Chile, Santiago, Chile</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Advanced Mining Technology Center (AMTC), Universidad de Chile, Santiago, Chile</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>NSF National Center for Atmospheric Research (NCAR), Boulder, Colorado, United States</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>now at: Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada</addr-line>
</aff>
<pub-date pub-type="epub">
<day>17</day>
<month>04</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>33</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Nicolás A. Vásquez et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1363/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1363/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1363/egusphere-2026-1363.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1363/egusphere-2026-1363.pdf</self-uri>
<abstract>
<p>Distributed hydrological models enable the characterization of spatial heterogeneities in states and fluxes, including streamflow at inner points of a basin. Despite the growing number of remotely sensed observations, calibrating the model parameters using only streamflow observed at the catchment outlet remains a popular practice. In this paper, we examine how streamflow-only calibration impacts the average seasonality and spatial patterns of simulated evapotranspiration (ET), soil moisture (SM), land surface temperature (LST), and fractional snow-covered area (fSCA). To this end, we conduct calibration experiments with the Variable Infiltration Capacity (VIC) model in six basins located in Chile, using (i) different streamflow-based objective functions, and (ii) regularizing parameters associated with different physical processes. For the latter step, we develop and test a novel spatial regularization strategy based on principal component analysis of physiographic attributes associated with the modeling units contained within each basin. Our results suggest that these decisions may have large effects on the spatial representation of ET, SM&lt;sub&gt;1&lt;/sub&gt; (i.e., SM from the first soil layer in VIC), LST, and fSCA, without degrading the performance of streamflow simulations. The average streamflow seasonality can be simulated reasonably well, with large biases in ET, fSCA, SM&lt;sub&gt;1&lt;/sub&gt;, and LST (in that order). In particular, different calibration configurations can yield the same annual cycle of streamflow through very different ET seasonalities, affecting the catchment-scale seasonal water balance. Additional calibration experiments incorporating ET and SM&lt;sub&gt;1&lt;/sub&gt; besides streamflow reaffirm tradeoffs in the fidelity of different simulated variables. Overall, the results presented here reinforce the benefits of including spatial patterns of hydrological variables in the calibration of distributed hydrological models and highlight the need to verify the seasonality of other simulated variables besides streamflow.</p>
</abstract>
<counts><page-count count="33"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>Agencia Nacional de Investigación y Desarrollo</funding-source>
<award-id>11200142</award-id>
<award-id>21230289</award-id>
<award-id>AFB230001</award-id>
</award-group>
<award-group id="gs2">
<funding-source>Global Affairs Canada</funding-source>
<award-id>Emerging Leaders in the Americas Program (ELAP)</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
<body/>
<back>
</back>
</article>