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<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-2026-4592</article-id>
<title-group>
<article-title>Compound Flooding in Surabaya: A Multi-driver Sensitivity and Interaction Analysis</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Larasari</surname>
<given-names>Agustia</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Reyns</surname>
<given-names>Johan</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Nawarat</surname>
<given-names>Khin</given-names>
<ext-link>https://orcid.org/0009-0003-2741-8896</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</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>Dastgheib</surname>
<given-names>Ali</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Civil and Resource Engineering, Dalhousie University, Halifax, Canada</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Coastal and Urban Risk &amp; Resilience Department, IHE Delft, Delft, the Netherlands</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Deltares, Delft, the Netherlands</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>University of Twente, Enschede, The Netherlands</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>International Marine and Dredging Consultants, Antwerp, Belgium</addr-line>
</aff>
<aff id="aff7">
<label>7</label>
<addr-line>Department of Civil Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia</addr-line>
</aff>
<pub-date pub-type="epub">
<day>20</day>
<month>08</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>36</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Agustia Larasari 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-2026-4592/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4592/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4592/egusphere-2026-4592.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4592/egusphere-2026-4592.pdf</self-uri>
<abstract>
<p>Coastal compound flooding, caused by interactions between various flood drivers, presents serious threats to urban coastal regions. In this study, a process-based modelling framework was applied by integrating statistical analysis of historical data with reduced-physics numerical simulations to assess compound flood hazards. A very low correlation between extreme sea level and heavy rainfall events in the study area was demonstrated, which confirmed the initial assumption of flood driver independence. Single-driver and compound-driver scenarios corresponding to a 100-year return period were simulated for present-day and future conditions, accounting for relative sea-level rise and intensified extreme rainfall under SSP2-4.5 and SSP5-8.5 by 2100. Results indicate that non-linear interactions between drivers lead to a considerable amplification of flood hazards. The primary impact mechanism is increased inundation depth within existing floodplains due to backwater effects, which affects 8.6 % to 20.9 % (10.7 to 36.6 km&amp;sup2;) of the total inundated area. A secondary effect is the expansion of the flood extent into previously unaffected areas by 0.82 % to 1.1 % (1 to 1.7 km&lt;sup&gt;2&lt;/sup&gt;) of the total inundated area. Climate change is projected to exacerbate these hazards substantially. Under the high-emission SSP5-8.5 scenario, a coastal compound event with a current 100-year return period is projected to occur as frequently as every 2&amp;ndash;3 years by 2100. This dramatic increase in frequency, along with a substantial rise in flood intensity, is primarily driven by sea-level rise.</p>
</abstract>
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