{"id":450660,"date":"2026-04-23T23:31:30","date_gmt":"2026-04-23T23:31:30","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/450660\/"},"modified":"2026-04-23T23:31:30","modified_gmt":"2026-04-23T23:31:30","slug":"remote-sensing-and-process-attribution-uncertainties-in-the-dharali-event","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/450660\/","title":{"rendered":"Remote sensing and process attribution uncertainties in the Dharali event"},"content":{"rendered":"

The event occurred during active monsoon conditions. Persistent rainfall can rapidly elevate pore-water pressures in saturated paraglacial sediments, triggering landslides and high-solid-fraction debris flows without requiring glacial detachment12<\/a>,13<\/a>. Paraglacial slopes in the Himalaya are particularly susceptible to rainfall-induced destabilization due to steep channel gradients, substantial supply of unconsolidated glacial sediments from a retreating glacier, and evolving permafrost conditions. Under such conditions, rainfall-triggered failures represent a physically sufficient and well-documented mechanism.<\/p>\n

This mechanism provides a coherent explanation for the occurrence of multiple debris flows within ~5\u2009h of the main Dharali (31\u00b0 2’26.05\u201cN; 78\u00b046’51.31\u201cE) event in the Kheer Gad catchment, for the contemporaneous flash flood reported in the adjacent Tel Gad catchment, which impacted the Harshil Army Camp (31\u00b0 2’4.31\u201cN; 78\u00b045’17.10\u201cE) located ~4\u2009km downstream of Dharali, and for another one near Lohari Nag Pala (30\u00b057’46.26\u201cN; 78\u00b041’52.01\u201cE), downstream of Sukhi (Fig. 4<\/a>). The near-synchronous nature and close spatial proximity of the source zones for these events are more consistent with a common hydrometeorological trigger upstream than with a localized, single-source cryospheric failure causing Dharali event1<\/a>.<\/p>\n

Fig. 4: Field photographs of the deposition zones of the three channels with proximalsource zones which experienced near-synchronous mudflows on 5 August 2025.<\/b>\"Fig.The alternative text for this image may have been generated using AI.<\/p>\n

a<\/b> An overview of the Dharali Village after the destructive mudflow. b<\/b> Mudflow deposits at Dharali. c<\/b> An overview of the Harshil Army Camp after the mudflow. d<\/b> A closer look of the Tel Gad channel. e<\/b> An overview of the Lohri Nag Pala after the debris flow. f<\/b> Debris flow deposits at Lohari Nag Pala.<\/p>\n

A rigorous process attribution framework requires systematic investigation of competing hypotheses for high-mountain mass movement events. For example, such debris flows can be caused by several triggers such as ice collapse, glacial lake outburst flood (GLOF), rock\u2013ice avalanche, rainfall-triggered landslide, followed by progressive channel bulking. The published interpretation1<\/a> does not demonstrate such hypothesis testing, instead, it privileges a cryospheric explanation without excluding simpler rainfall-driven mechanisms. A recent article8<\/a> on this event is a good example of multiple possibility consideration, where the author has investigated rainfall triggered reactivation of older landslide, GLOF, and wind convergence, as several potential or interacting triggers.<\/p>\n

Another analysis14<\/a> of the Dharali event and several similar events across the Uttarakhand state have proved that the frequency, magnitude, and direct loss due to landsliding in 2025 was significantly higher mainly due to intense rainfall and cloudbursts. The study14<\/a> reported that the variance of the rainfall data during August-September 2025 was relatively higher indicating intense and distinct rainfall peaks. The rainfall during June-September 2025 was also considerably higher throughout the state compared to previous years, including a total rainfall of 4808.6\u2009mm in Gaurikund (Rudraprayag), 1321.6\u2009mm in Kalagarh (Pauri Garhwal), 1547.8\u2009mm in Pipalkoti (Chamoli), and 1701.8\u2009mm in Uttarkashi14<\/a>. All these places also experienced multiple landslides and mudflow events, thus, highlighting a potential atmospheric hydrometeorological trigger which was a large-scale phenomenon impacting several valleys across the state of Uttarakhand.<\/p>\n","protected":false},"excerpt":{"rendered":"The event occurred during active monsoon conditions. Persistent rainfall can rapidly elevate pore-water pressures in saturated paraglacial sediments,…\n","protected":false},"author":2,"featured_media":450661,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[269],"tags":[86364,18705,18,440,63772,19,17,7021,133,198618],"class_list":["post-450660","post","type-post","status-publish","format-standard","has-post-thumbnail","category-environment","tag-atmospheric-sciences","tag-climate-sciences","tag-eire","tag-environment","tag-environmental-policy","tag-ie","tag-ireland","tag-natural-hazards","tag-science","tag-solid-earth-sciences"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/116456632483256418","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/450660","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=450660"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/450660\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/450661"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=450660"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=450660"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=450660"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}