@article{BartholdTurnerElsenbeeretal.2017, author = {Barthold, Frauke Katrin and Turner, Benjamin L. and Elsenbeer, Helmut and Zimmermann, Alexander}, title = {A hydrochemical approach to quantify the role of return flow in a surface flow-dominated catchment}, series = {Hydrological processes}, volume = {31}, journal = {Hydrological processes}, number = {5}, publisher = {Wiley}, address = {Hoboken}, issn = {0885-6087}, doi = {10.1002/hyp.11083}, pages = {1018 -- 1033}, year = {2017}, abstract = {Stormflow generation in headwater catchments dominated by subsurface flow has been studied extensively, yet catchments dominated by surface flow have received less attention. We addressed this by testing whether stormflow chemistry is controlled by either (a) the event-water signature of overland flow, or (b) the pre-event water signature of return flow. We used a high-resolution hydrochemical data set of stormflow and end-members of multiple storms in an end-member mixing analysis to determine the number of end-members needed to explain stormflow, characterize and identify potential end-members, calculate their contributions to stormflow, and develop a conceptual model of stormflow. The arrangement and relative positioning of end-members in stormflow mixing space suggest that saturation excess overland flow (26-48\%) and return flow from two different subsurface storage pools (17-53\%) are both similarly important for stormflow. These results suggest that pipes and fractures are important flow paths to rapidly release stored water and highlight the value of within-event resolution hydrochemical data to assess the full range and dynamics of flow paths.}, language = {en} } @article{WetterichSchirrmeisteNazarovaetal.2018, author = {Wetterich, Sebastian and Schirrmeiste, Lutz and Nazarova, Larisa B. and Palagushkina, Olga and Bobrov, Anatoly and Pogosyan, Lilit and Savelieva, Larisa and Syrykh, Liudmila and Matthes, Heidrun and Fritz, Michael and G{\"u}nther, Frank and Opel, Thomas and Meyer, Hanno}, title = {Holocene thermokarst and pingo development in the Kolyma Lowland (NE Siberia)}, series = {Permafrost and Periglacial Processes}, volume = {29}, journal = {Permafrost and Periglacial Processes}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {1045-6740}, doi = {10.1002/ppp.1979}, pages = {182 -- 198}, year = {2018}, abstract = {Ground ice and sedimentary records of a pingo exposure reveal insights into Holocene permafrost, landscape and climate dynamics. Early to mid-Holocene thermokarst lake deposits contain rich floral and faunal paleoassemblages, which indicate lake shrinkage and decreasing summer temperatures (chironomid-based T-July) from 10.5 to 3.5 cal kyr BP with the warmest period between 10.5 and 8 cal kyr BP. Talik refreezing and pingo growth started about 3.5 cal kyr BP after disappearance of the lake. The isotopic composition of the pingo ice (delta O-18 - 17.1 +/- 0.6 parts per thousand, delta D -144.5 +/- 3.4 parts per thousand, slope 5.85, deuterium excess -7.7 +/- 1.5 parts per thousand) point to the initial stage of closed-system freezing captured in the record. A differing isotopic composition within the massive ice body was found (delta O-18 - 21.3 +/- 1.4 parts per thousand, delta D -165 +/- 11.5 parts per thousand, slope 8.13, deuterium excess 4.9 +/- 3.2 parts per thousand), probably related to the infill of dilation cracks by surface water with quasi-meteoric signature. Currently inactive syngenetic ice wedges formed in the thermokarst basin after lake drainage. The pingo preserves traces of permafrost response to climate variations in terms of ground-ice degradation (thermokarst) during the early and mid-Holocene, and aggradation (wedge-ice and pingo-ice growth) during the late Holocene.}, language = {en} }