Cryoplanation terraces at the Seward Peninsula: mechanisms of origin and influence on subsurface hydrology on the local scale
Abstract
Slope terraces are widespread feature at the Seward Peninsula. Many researches identify these landforms as solifluction lobs. But in fact the solifluction is the process of the flowage of the soil of active (seasonally frozen) layer oversaturated with water down a steep slope. So it is strongly associated with permafrost. At the same time we notice these feathers not only on the north facing slopes, underlined by permafrost but as well on the south slopes where permafrost is detached from the seasonally frozen layer where surface soil layer is undersaturated. We assume that in this region within the areas where permafrost absence close to ground surface these features originated in result of solifluction during the cold epochs now days are subjectd to development of the neval processes i.e. influence of perannual or late-lying snow patches. These landforms control the redistribution of snow during winter seasons and, thus controls soil temperature and moisture regime. In September of 2017 we established the 70 meters long observation transects across one of the slope terraces at the milepost 28 of the Teller road. We installed temperature sensors at the ground surface and the depths of 20, 50 and 120 cm in three points located in the rear, central and front parts of the terrace. We also conducted vegetation, soil and snow surveys along the transect. In according to our results at the spring time of the 2018 snow thickness across the terrace decreases from the 1.8 m in the rear part to less than 30 cm at the front. It provides the conditions for permafrost preservation at the front part, while at the rear we observe only shallow (about 30 cm) seasonal freezing. This thin seasonally frozen layer thaws completely soon after the melting of snow cover that allows melted water and precipitation to infiltrate to deeper horizons during the summer. Presence of permafrost close to the ground surface at the frontal parts of these terraces creates series of "frozen dumbs" across the slope. These dumbs make longer the paths of downhill flow of ground water and sometimes can event create local water catchments.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H21K1809K
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0438 Diel;
- seasonal;
- and annual cycles;
- BIOGEOSCIENCESDE: 1807 Climate impacts;
- HYDROLOGYDE: 1836 Hydrological cycles and budgets;
- HYDROLOGY