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Just published: our recent studies

The list of last scientific papers of the Department of Physical Geography and Geoecology.

Nedelcev O., Jenicek, M. (2021). Trends in seasonal snowpack and their relation to climate variables in mountain catchments in Czechia. Hydrological Sciences Journal, 66(16), 2340-2356.

This study investigated trends in snowpack for the period 1965–2014 in 40 catchments located in five mountain regions in Czechia. We analysed daily series of air temperature, precipitation, and snow water equivalent (SWE) that were simulated with a conceptual model. The Mann-Kendall test showed strong increasing trends in air temperature at all elevations, mostly at the end of the cold season. This increase caused a decrease in snowfall fraction and SWE. Maximum SWE decreased mainly in western parts of Czechia (by up to −45 mm/decade). The length of the snow-covered period decreased by up to −6.8 days/decade, mainly due to earlier melt-out. Snowpack was more sensitive to changes in air temperature at elevations below 900 m a.s.l., while precipitation had a larger impact on snowpack at elevations above 1200 m a.s.l. The relative importance of air temperature for snow variability increased at all elevations in the last few decades.

Dalton, A.S., Stokes, C.R., Batchelor, C.L. (2022). Evolution of the Laurentide and Innuitian ice sheets prior to the Last Glacial Maximum (115 ka to 25 ka)Earth-Science Reviews, 224, 103875. 

The Laurentide Ice Sheet was the largest global ice mass to grow and decay during the last glacial cycle (~115 ka to ~10 ka). Despite its importance for driving major changes in global mean sea level, long-term landscape evolution, and atmospheric circulation patterns, the history of the Laurentide (and neighbouring Innuitian) Ice Sheet is poorly constrained owing to sporadic preservation of stratigraphic records prior to the Last Glacial Maximum (~25 ka) and a case-study approach to the dating of available evidence. Here, we synthesize available geochronological data from the glaciated region, together with published stratigraphic and geomorphological data, as well as numerical modelling output, to derive 19 hypothesised reconstructions of the Laurentide and Innuitian ice sheets from 115 ka to 25 ka at 5-kyr intervals, with uncertainties quantified to include best, minimum, and maximum ice extent estimates at each time-step.

Juras, R., Blöcher, J.R., Jenicek, M., Hotovy, O., Markonis, Y. (2021). What affects the hydrological response of rain-on-snow events in low-altitude mountain ranges in Central Europe? Journal of Hydrology, 603(C), 127002.

Rain-on-snow (ROS) events influence the hydrological regime of rivers in regions with seasonal snow cover. We analysed eleven years of hourly meteorological, snow water equivalent and streamflow data from 15 catchments located in two mountain ranges in Czechia. We identified 611 ROS events which were further analysed and classified using selected meteorological, snow and runoff indices. The analysis of the runoff response of all ROS events revealed that only 5% of them resulted in high runoff exceeding the 1-year return period, but most of the events (82%) did not cause any significant runoff increase. High volumes of rain together with low snow cover were identified as important factors in the generation of high runoffs. In contrast, a deep and extended snowpack affected by rain under low air temperatures usually caused lower runoffs. The results of this study showed the importance of the snowpack, which can often prevent extreme runoff even when a large amount of rainfall occurs. 

Minařík, R., Langhammer, J., Lendzioch, T., 2021. Detection of Bark Beetle Disturbance at Tree Level Using UAS Multispectral Imagery and Deep Learning. Remote Sensing 13, 4768.

This study aimed to examine the potential of convolutional neural networks (CNNs) for the detection of individual trees infested by bark beetles in a multispectral high-resolution dataset acquired by an unmanned aerial system (UAS). We compared the performance of three CNN architectures and the Random Forest model to classify the trees into four categories: pines, healthy spruce, longer infested spruce trees when needles turn yellow,  and spruce trees under green attack. Based on our findings, we conclude that the CNN models are superior to the RF models and enable building learning models for the identification of infested trees and for distinguishing between different infestation stages. We see the potential application of the tested workflow in combination with multitemporal analysis for monitoring bark beetle disturbance, detecting hotspots, and predicting infestation spreading.

Tumajer, J., Buras, A., Camarero, J. J., Carrer, M., Shetti, R., Wilmking, M., Altman, J., Sangüesa-Barreda, G., & Lehejček, J. (2021). Growing faster, longer or both? Modelling plastic response of Juniperus communis growth phenology to climate changeGlobal Ecology and Biogeography, 30, 2229– 2244.

Common juniper (Juniperus communis) is the most widely distributed woody plant. Its range spreads across most of the northern hemisphere including Eurasia, North America, and Arctics. Juniper is a resistant shrub that survives in both extremely dry and cold environments. We tested whether intraannual growth patterns (i.e., timing and intensity of wood formation during the year) and their responses to climate change vary between contrasting environments. We used a process-based model to simulate the variability of wood formation at 16 sites and over 70 years of climate change. Geographically, there are three distinct intraannual growth patterns typical for cold (Arctic + Northern Ural), dry (Mediterranean + Southern Ural), and wet (Alps) environments. Recently, dry regions showed an extension of the growing season, but declining growth rates due to climate change (growing for longer, but not faster). By contrast, growth rates increased, but the duration of the growing season remained stable in cold environments (growing faster, but not longer). High intraannual growth plasticity enabled junipers to couple their intraannual growth dynamics with the local pattern of climate change. This might constitute an important advantage that facilitated the expansion of junipers to their large geographical range. 

Jenicek, M., Hnilica, J., Nedelcev, O., Sipek, V. (2021). Future changes in snowpack will impact seasonal runoff and low flows in Czechia. Journal of Hydrology: Regional Studies, 37, 100899.

Mountains are referred to as “water towers” because they substantially affect the hydrology of downstream areas. Main objectives of this study were 1) to simulate the future changes in snow for a large set of mountain catchments in Czechia, reflecting a wide range of climate projections and 2) to analyse how the snow changes will affect groundwater recharge, streamflow seasonality and low flows in the future. The future hydrological projections showed a decrease in annual maximum SWE by 30 %–70 % in the study area until the end of the 21st century. Additionally, snowmelt was found to occur on average 3–4 weeks earlier. Changes in snowpack will cause the highest streamflow during melting season to occur one month earlier, in addition to lower spring runoff volumes due to lower snowmelt inputs. The future climate projections leading to overall dry conditions in summer are associated with both the lowest summer precipitation and seasonal snowpack. The expected lower snow storages might therefore contribute to more extreme low flow periods.

Kropáček, J., Vilímek, V. & Mehrishi, P. A preliminary assessment of the Chamoli rock and ice avalanche in the Indian Himalayas by remote sensingLandslides (2021).

On 7 February 2021, a process chain disaster hit tributaries of the upper Alaknanda river in the Indian Himalayas referred to as the Chamoli disaster in the media. A large rock and ice avalanche was released from an elevation of approximately 5,100 m a.s.l. The avalanche turned into a debris flow and further downstream into a flood, leaving behind four damaged hydropower projects and dozens of casualties. The initially dry flow, as indicated by dust observed on a satellite image, turned into a moist flow by entrainment of water from water courses, snow and sediment. Using satellite images from Sentinel-2 and PlanetScope, we were able to map the geometry of the event. Furthermore, satellite data allowed us to reveal a drop in the snow line elevation of approximately 1,500 m, which indicated a snow fall three days before the event. We were also able to track the flood front propagation four days after the slope collapse. The analysis of temperature data from a near weather station indicated below zero temperatures in the detachment zone one month before the event and a temperature increase in the morning of the event. We suggest that the weather conditions may have been the final trigger, whereas a heavy predisposition was given mainly by the structural and morphological aspects of the slope.

Šípek, V., Jenicek, M., Hnilica, J., Zelíková, N. (2021). Catchment storage and its influence on summer low flows in central European mountainous catchments. Water Resources Management. 35, 2829–2843.

The objective of this study was to determine the role of spring catchment water storage on the evolution of low flows in central European mountainous catchments. The study analysed 58 catchments for which catchment storage, represented by snow, soil water and groundwater storages, was determined by the HBV hydrological model over a 35-year period.  The mean runoff in the summer and autumn periods was mostly related to rainfall sums from the respective season. The median relative contribution of rainfall to the total mutual information value was 48.4% in summer, and 44.2% in autumn period, respectively. The relative contribution of soil water and groundwater storages was approximately 25% for each of the components. In contrast, the minimum runoff, its duration and deficit runoff volume, were equally related to both catchment storage and seasonal rainfall, especially in the autumn period.

Ben J. Stoker, Stephen J. Livingstone, Iestyn D. Barr, Alastair Ruffell, Robert D. Storrar, Sam Roberson (2021). Variations in esker morphology and internal architecture record time-transgressive deposition during ice margin retreat in Northern Ireland. Proceedings of the Geologists' Association, 132, (4), 409-425.

The subglacial hydrological system has a strong influence on variations in ice flow velocity. Eskers are sinuous ridges formed as water beneath a glacier deposits sediment within a subglacial channel. We used ground penetrating radar to investigate the internal architecture of a large esker system. We identified that the eskers were formed by two styles of deposition. Subglacial deposition of poorly-sorted sediment forms the esker core. Then, the deposition of more well-sorted, delta sediments which are superimposed on the esker in certain locations. This sequence of deposition occurred repeatedly during ice margin retreat. Despite variations in esker morphology, the internal structure remained consistent. Therefore, the variations in esker morphology cannot be explained by past subglacial flow processes alone. Instead, topography seems to be a strong control on esker morphology in this region.

Norris, S. L., Garcia-Castellanos, D., Jansen, J. D., Carling, P. A., Margold, M., Woywitka, R. J., & Froese, D. G. (2021). Catastrophic drainage from the northwestern outlet of glacial Lake Agassiz during the Younger DryasGeophysical Research Letters, 48, e2021GL093919.

The Younger Dryas was a short-lived interval of cooling that interrupted warming during the last deglaciation. The cause of this rapid change in climate is debated. One suggestion is the drainage of meltwater from glacial Lake Agassiz, a large ice-dammed lake in central North America, into the surrounding oceans may have affected ocean circulation, contributing to this climatic event. Here we model the discharge of water from the northwestern outlet of this lake. We estimate the discharge and demonstrate the connection between Lake Agassiz and the Arctic Ocean during the Younger Dryas.

Helen E. Dulfer & Martin Margold (2021). Glacial geomorphology of the central
sector of the Cordilleran Ice Sheet, Northern British Columbia, Canada
. Journal of Maps, DOI:

Northern British Columbia was repeatedly covered by the Cordilleran Ice Sheet (CIS) during the glacial periods. However, its mountainous terrain and remote location have thus far impeded our understanding of the central sector of the ice sheet. In this study we use high resolution remotely sensed data to map glacial landforms across this inaccessible region and thousands of previously unrecognised glacial landforms have been mapped including eskers, moraines, meltwater channels, kame terraces and subglacial ribs. Our glacial geomorphological map can now be used to unravel the complex glacial history beneath the LGM ice divide region of the CIS and help us to better understand the advance and retreat dynamics of this ephemeral Pleistocene ice sheet.

Vlach, V., Matoušková, M., & Ledvinka, O. (2021). Impacts of regional climate change on hydrological drought characteristics in headwaters of the Ore Mountains. River Research and Applications, 1–12. 

Recent years suggested an increasing risk of drought occurrence and restricted water supply even in usually humid mountain regions. This study was focused on the effects of regional climate change on hydrological drought characteristics in headwaters of the Ore Mountains along the Czech/German border. Results pointed to significant, continuous warming in the region which is accompanied by decreasing trends in snow cover depths in the colder half of the year. The seasonality of hydrological droughts changed markedly after 1992, when most severe drought events started to concentrate between August and October within the study area. Increasing trends in deficit volumes were found in two catchments along with a significant decrease in average and minimum flows in spring and summer months between 1967 and 2018.

Dulfer, H., Margold, M., Engel, Z., Braucher, R., & Team, A. (2021): Using 10Be dating to determine when the Cordilleran Ice Sheet stopped flowing over the Canadian Rocky Mountains. Quaternary Research, 1-12.

The Cordilleran Ice Sheet (CIS) repeatedly covered the mountainous regions of western North America during the Pleistocene and formed part of the North American Ice Sheet Complex during the last glacial maximum (LGM). This paper confirms the eastward flow of the CIS over the Rocky Mountains during the LGM and uses in situ produced cosmogenic 10Be dating at two high elevation sites to determine when the Cordilleran Ice Sheet retreated from the central Canadian Rocky Mountains. Deglaciation at the eastern site (Mt Spieker) occurred around 15.6 ka while the western site (Mt Morfee) was inundated with ice from the west until the Younger Dryas stadial (around 12.2 ka). Our results represent the first application of 10Be dating on the deglaciation history in the Canadian Rocky Mountains and provide valuable new data on the timing of deglaciation of the central sector of the CIS.

Uxa, T., Křížek, M., and Hrbáček, F. (2021): PERICLIMv1.0: a model deriving palaeo-air temperatures from thaw depth in past permafrost regions, Geosci. Model Dev., 14, 1865–1884.

This study presents and evaluates a simple new inverse modelling scheme called PERICLIMv1.0 (PERIglacial CLIMate) that derives palaeo-air temperature characteristics related to the palaeo-active-layer thickness, which can be recognized using many relict periglacial features found in past permafrost regions. The evaluation against modern temperature records showed that the model reproduces air temperature characteristics with average errors ≤1.3 ∘C. The past mean annual air temperature modelled experimentally for two sites in the Czech Republic hosting relict cryoturbation structures was between -7.0 ±1.9 and -3.2±1.5 ∘C, which is well in line with earlier reconstructions utilizing various palaeo-archives. These initial results are promising and suggest that the model could become a useful tool for reconstructing Quaternary palaeo-environments across vast areas of mid-latitudes and low latitudes where relict periglacial assemblages frequently occur, but their full potential remains to be exploited.

Hartvich, F., Tábořík, P., Šobr, M., Janský, B., Kliment, Z., and Langhammer, J. (2020): Landslide‐dammed lake sediment volume calculation using waterborne ERT and SONAR profiling. Earth Surf. Process. Landforms, 45: 3463– 3474.

Experimental stationary ERT profiling across a landslide‐dammed lake using custom‐made flotation devices was performed. Combining with the SONAR sounding proved very suitable and yielded very good results allowing to reconstruct original lake floor. Sediment volume accumulated during 145 years long history of the lake was calculated. Sedimentation velocity was assessed to predict the future development of the lake.

Tumajer J, Kašpar J, Kuželová H, Shishov VV, Tychkov II, Popkova MI, Vaganov EA and Treml V (2021): Forward Modeling Reveals Multidecadal Trends in Cambial Kinetics and Phenology at Treeline. Front. Plant Sci. 12:613643.

Woody plants experience prominent variability in their annual growth rates due to climate change. Increasing temperature stimulates formation of wider tree-rings mainly in cold environments but associated higher drought stress can reduce the tree-ring formation at dry locations. However, it is not known whether this alteration of growth is due to shifting phenology (changing growing season duration) or trends in growth kinetics (the production of cells is faster/slower). We seek the answer for this question at the treeline of the Krkonoše Mts. We employed the Vaganov-Shashkin process-based model of tree-ring formation to ‘slice’ the tree-ring width into daily growth segments. By the analysing specific model outputs, we were able to identify two main drivers of increased tree-ring widths of treeline trees since 1960 – (i) higher summer rate of cell production due to temperature increase and (ii) earlier spring onset of cambial activity. By contrast, autumn growth rates and phenology do not show significant trends. Surprisingly, we observed a clear pattern of drought stress on trees during warm and dry summer days controlling the formation of around 22 % of tree ring. The increasing drought stress might slow-down the future positive response of a cold treeline ecosystems to increasing temperature.

Lendzioch T, Langhammer J, Vlček L, Minařík R. (2021): Mapping the Groundwater Level and Soil Moisture of a Montane Peat Bog Using UAV Monitoring and Machine Learning. Remote Sensing. 13(5):907. 

This paper presents a novel approach for using UAV thermal and multispectral imagery to enhance the spatio-temporal predictions of groundwater level and top-layer soil moisture of montane peat bogs using a machine learning model. Our research aimed to obtain information and predict the dynamic properties of groundwater level (GWL) and top-layer soil moisture (SM) in 2 dimensions and time based on data from digital surface models (DSMs), RGB, multispectral, and thermal data from drone imagery. We used a CAST spatiotemporal Machine Learning (ML) prediction model using the Random Forest algorithm. For two seasons, we have launched recurrent UAV monitoring campaigns and field sampling of GWL and SM ground truth data at the Rokytka Peat bog within the Sumava Mountains, Czechia. We used 34 predictors, derived from UAV imaging datasets to feed the random forest model. Results showed that the ML model, using the UAV-derived datasets, delivers accurate predictions of GWL and SM spatial distribution. The method is well suited and unique for planning and decision-making about the best sampling strategy, most notably with limited data.

Engel, Z., Křížek, M., Braucher, R., Uxa, T., Krause, D., Aster Team (2021): 10Be exposure age for sorted polygons in the Sudetes Mountains. Permafrost and Periglacial Processes, 32, 1, 154-158.

Tento článek jako první na světě datuje tříděné strukturní půdy pomocí kosmogenního radionuklidu 10Be. Poskytuje prahové hodnoty numerického datování pro reliktní polygony odebrané na čtyřech místech ve Vysokých Sudetech (Luční hora a Vysoké Kolo v Krkonoších, Břidličná a Větrná louka v Hrubém Jeseníku, které představují nejvyšší oblast středoevropských středohor). Výsledky naznačují, že se tyto tvary začaly formovat na konci MIS 3 a hlavní fáze jejich formování proběhla před 30 až 20 tis. lety. Tento článek potvrzuje hypotézu formování tříděných polygonů během posledního (viselského) glaciálu (před 110,6-11,7 tis. lety) a naznačuje, že případné starší tříděné polygony se nezachovaly. Identifikované období zvýšené periglaciální aktivity tříděných polygonů odpovídá v regionálním i nadregionálním měřítku drsnějšímu klimatickému období identifikovanému i jinými proxy daty získanými ze severní polokoule.


Published: Jan 07, 2022 12:00 AM

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