Landslide dams acting as sediment traps: Example of the lake Hintersee, Berchtesgadener Land, south-eastern Germany&#160;
Authors: Hauthaler Thomas , Argentin Anne-Laure , Robl Jörg , Prasicek Günther , Hölbling Daniel , Hergarten Stefan , Abad Lorena , Dabiri Zahra 
Published: March 2021

&lt;p&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Landslide dams occur when a landslide deposits in the riverbed and stop the river flow, creating lakes. They act as big sediments traps that modify the sediment flux in the whole catchment. By changing the sediment load, &lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;the dams &lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;change the erosion rates upstream and downstream. Although most landslide-dammed lakes are ephemeral, some stay in place and disappear only when they have been filled with sediments. We study the &lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Hintersee&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;lake in the&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Berchtesgadener&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;Land&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;, Germany, and aim to determine the sediment budget of the infilled lake and the dam&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;duration &lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;before breaching. This landslide dam formed 3520 years BP from a rockslide of 15-18 x 10&lt;/span&gt;&lt;/span&gt;&lt;sup&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;6&lt;/span&gt;&lt;/span&gt;&lt;/sup&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;m&lt;/span&gt;&lt;/span&gt;&lt;sup&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;3&lt;/span&gt;&lt;/span&gt;&lt;/sup&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;. We propose to reproduce the formation of the&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Hintersee&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;landslide dam and its infilling using different scenarios. We first use a 1 m resolution digital elevation model to rebuild the valley floor before the rockslide event, three different rockslide source areas and the landslide dam shape before fluvial incision. We apply the&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Gerris&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;shallow water flow solver to simulate the landslide runout and to recreate the landslide dam deposition characteristics from the different source topographies and several&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Voellmy&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;rheologies&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;. We&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;choose&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;&amp;#160;the best-fitting scenario to assess&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;a sediment budget of the&amp;#160;&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt;Hintersee&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;none&quot;&gt;&lt;span&gt; landslide-dammed lake.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;