Publication Date:
2021-07-19
Description:
The summer water balance of a typical Siberian
polygonal tundra catchment is investigated in order to
identify the spatial and temporal dynamics of its main
hydrological processes. The results show that, besides
precipitation and evapotranspiration, lateral flow considerably
influences the site-specific hydrological conditions.
The prominent microtopography of the polygonal tundra
strongly controls lateral flow and storage behaviour of the
investigated catchment. Intact rims of low-centred polygons
build hydrological barriers, which release storage
water later in summer than polygons with degraded rims
and troughs above degraded ice wedges. The barrier
function of rims is strongly controlled by soil thaw, which
opens new subsurface flow paths and increases subsurface
hydrological connectivity. Therefore, soil thaw dynamics
determine the magnitude and timing of subsurface outflow
and the redistribution of storage within the catchment.
Hydraulic conductivities in the elevated polygonal rims
sharply decrease with the transition from organic to
mineral layers. This interface causes a rapid shallow
subsurface drainage of rainwater towards the depressed
polygon centres and troughs. The re-release of storage
water from the centres through deeper and less conductive
layers helps maintain a high water table in the surface
drainage network of troughs throughout the summer.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
