<p>Glacial lake outburst floods (GLOFs) have occurred across the planet throughout the Quaternary and are a significant geohazard in Arctic and alpine regions today. Iceland experiences more frequent GLOFs&#8212;known in Icelandic as j&#246;kulhlaups&#8212;than nearly anywhere on Earth, yet most research focuses on floods triggered by subglacial volcanic and geothermal activity. However, floods from proglacial lakes may be a better analogue to most global GLOFs.</p><p>As the Icelandic Ice Sheet retreated across Iceland in the Late Pleistocene-Early Holocene, meltwater pooled at ice margins and periodically drained in j&#246;kulhlaups. Some of the most catastrophic floods drained from ice-dammed Glacial Lake Kj&#246;lur, surging across southwestern Iceland from the interior highlands to the Atlantic Ocean. These floods left extensive geomorphologic evidence along the modern-day course of the Hv&#237;t&#225; River, including canyons, scoured bedrock, boulder deposits, and Gullfoss&#8212;Iceland&#8217;s most famous waterfall. The largest events reached an estimated maximum peak discharge of 300,000 m<sup>3</sup> s<sup>-1</sup>, ranking them among the largest known floods in Iceland and on Earth.</p><p>Yet, all our evidence for the Kj&#246;lur j&#246;kulhlaups comes from only one publication to date (T&#243;masson, 1993). My research employs new methods to better constrain flood timing, routing, magnitude, and recurrence interval at this underexplored site. This talk presents new and synthesized j&#246;kulhlaup geomorphologic evidence; HEC-RAS hydraulic modeling results of flow magnitude and routing; and ongoing geochronological analyses using cosmogenic nuclide exposure dating and tephrochronology. It also situates these events within Icelandic Ice Sheet deglaciation chronology and environmental change at the Pleistocene-Holocene transition. Finally, it examines the Kj&#246;lur floods as an analogue to contemporary ice sheet response, proglacial lake formation, and j&#246;kulhlaup processes and landscape evolution in Arctic and alpine regions worldwide, where GLOFs pose an increasing risk to downstream communities due to climate-driven meltwater lake expansion. &#160;</p><p>Citation: T&#243;masson, H., 1993. J&#246;kulst&#237;flu&#240; v&#246;tn &#225; Kili og hamfarahlaup &#237; Hv&#237;t&#225; &#237; &#193;rness&#253;slu. N&#225;tt&#250;rufr&#230;&#240;ingurinn 62, 77-98.</p>