Recent dynamics of hydro-ecosystems in thermokarst depressions in Central Siberia from satellite and in situ observations: Importance for agriculture and human life

• Published in: Science of The Total Environment
• Main Authors: Zakharova, Elena, Kouraev, Alexei, Guillaso, Stephane, Garestier, Franck, Desyatkin, Roman, Desyatkin, Alexey
• Other Authors: Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Water Problems Institute of the Russian Academy of Sciences, Russian Academy of Sciences Moscow (RAS), Tomsk State University Tomsk, Technical University of Berlin / Technische Universität Berlin (TU), GIPSA - Signal Images Physique (GIPSA-SIGMAPHY), Département Images et Signal (GIPSA-DIS), Grenoble Images Parole Signal Automatique (GIPSA-lab ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Grenoble Images Parole Signal Automatique (GIPSA-lab ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Landsat-8; Fodder supply; Lake water regime; Grasslands productivity; Satellite altimetry; Alas; Yakutia; Local agriculture; TerraSAR-X; [SDU]Sciences of the Universe [physics]; Thermokarst; Siberia
• Online Access: https://hal.science/hal-01691983; https://doi.org/10.1016/j.scitotenv.2017.09.059

(IF 5.59; Q1) International audience Alases, which are thermokarst depressions that are occupied by grasslands and lakes, are an important element of the Central Yakutian periglacial landscape. In recent decades, climatic changes in Central Yakutia have resulted in important changes in environmental conditions. We use different remote-sensing instruments (Landsat 8, TerraSAR-X, ENVISAT-RA2, and Jason-2) alongside in situ observations to investigate 1) the spatial distribution and water regime of alas lakes and their relationships with climatic and geomorphologic factors, 2) the relationship of the alas' grassland productivity with the water regime and 3) the potential of alas grasslands for local agriculture. During the 2002–2010 period, the lake water level rose by 1.3 m on average, resulting in lake expansion throughout the region. Since 2011, the lake area decreased and the water level declined by 70 cm on the middle terraces (low ground-ice content), while the wetting trend continued until 2016 at higher elevations. Small thermokarst lakes (< 0.025 km2), which indicate regions of young thermokarst, comprise up to 11% of the total lake area and experience high (30%) seasonal variations. In situ observations of the grassland dynamics show their synchronous cyclic variability with the lake extent and a general increasing trend for their productivity since 1985. Around 50% of these dynamics can be explained by the amount of pre-winter precipitation with a delay of two years. We explain this delay through the buffering effect of watershed soils. The cyclic variability of alas hydro-ecosystems strongly affects the local agriculture, which is based on horse and cattle breeding. We estimate that these alas grasslands can provide enough forage supply for local communities. However, the real alas yield is several times less than the theoretical value because of grassland degradation that is caused by recent thermokarst and waterlogging in the most productive phytocenosis.