Geomorphology of the lake shewa landslide dam, badakhshan, afghanistan, using remote sensing data

Abstract

Lake Shewa in northeastern Badakhshan, Afghanistan, was dammed sometime in antiquity when a large rock avalanche (sturzstrom) from the faultshattered and strongly weathered Archean gneisses of the Zirnokh peaks to the north moved into the Arakht River valley. This rock avalanche dammed up the river and its tributaries to a dam thickness of c. 400 m, producing a 12-km-long lake that is as much as 270 m deep, leaving c. 80 m of freeboard to the top of the dam. At least four separate instances of slope failure have been mapped at the site of the landslide dam, as well as a rock glacier, using remotely sensed data, historical maps, and Google Earth™. Spring seepage through the dam face has caused several recent subsidiary debris slides, which if continued at a large enough scale for long enough, or with additional seismicity from the active strike-slip faults that cross beneath the landslide dam, could threaten its integrity. Otherwise the clean water that emerges from the dam face could be the source of an unvarying mini-hydroelectric power source, in addition to the agricultural irrigation that it provides at the present time.

Database and spatial distribution of landslides triggered by the Lushan, China Mw 6.6 earthquake of 20 April 2013

“…Such a phenomenon is also observed in the Wenchuan earthquake-triggered landslides , probably because many intrusive rocks crops out along the Longmenshan fault, and the movement of the fault would have weakened the strength of these rocks. Similar tectonic weakening effects have also been noticed in previous studies (Kellogg, 2001;Fisher, 2003;Korup, 2004;Osmundsen et al, 2009;Shroder and Weihs, 2010).…”

Watersheds of Want

“…A number of prior visitors ( Lindberg, 1961;Sawata, 1962;Desio, 1975) thought that the dam was glacial moraine, but Ruleman et al (2007) and Shroder and Weihs (2010) first recognized the slope-failure origin. Lake Shewa was dammed sometime in antiquity when a large rock avalanche (sturzstrom) from the fault-shattered and strongly weathered Archean gneisses of the Zirnokh peaks to the north moved down into the Arakht River valley.…”

Terrains of Torment

“…A large rock-slope failure from the fault-shattered and strongly weathered Zirnokh peaks to the north moved into the valley and dammed up the river and its tributaries to a dam thickness of ∼400 m, producing a 12-km-long lake that is as much as 270 m deep, leaving ∼80 m of freeboard to the top of the dam. At least five separate slope failures have been mapped at the site of the landslide dam where two strike-slip faults cross each other and presumably contribute to instability (Shroder and Weihs, 2010). The uppermost part of the Lake Shewa landslide dam is a prominent rock glacier, which as a slow moving accumulation of rock debris and internal ice cement, takes centuries to millennia to form, and thus testifies to the antiquity of the dam.…”

“…Other overlying and associated features developed over a long period of time, which attests to the considerable antiquity of the landslide feature. Lake Shiwa (or Shewa), a body of water about 15 km 2 in area in northeastern Badakhshan about 10 km from the Panj River border with Tajikistan also was dammed sometime in antiquity by one or more landslides (Shroder and Weihs, 2010). A large rock-slope failure from the fault-shattered and strongly weathered Zirnokh peaks to the north moved into the valley and dammed up the river and its tributaries to a dam thickness of ∼400 m, producing a 12-km-long lake that is as much as 270 m deep, leaving ∼80 m of freeboard to the top of the dam.…”