Physically based hydrogeological and slope stability modeling of the Turaida castle mound

This study explores the potential of integrating state-of-the-art physically based hydrogeological modeling into slope stability simulations to identify the hydrogeological triggers of landslides. Hydrogeological models considering detailed morphological, lithological, and climatic factors were elaborated. Groundwater modeling reveals locations with elevated pore water pressures in the subsurface and allows the quantification of temporal dynamics of the pore water pressures. Results of the hydrogeological modeling were subsequently applied as boundary conditions for the slope stability simulations. The numerical models illustrate that the hydrogeological impacts affecting hillslope stability are strongly controlled by local groundwater flow conditions and their conceptualization approach in the hydrogeological model. Groundwater flow itself is heavily influenced by the inherent geological conditions and the dynamics of climatic forcing. Therefore, both detailed investigation of the landslide’s hydrogeology and appropriate conceptualization and scaling of hydrogeological settings in a numerical model are essential to avoid an underestimation of the landslide risk. The study demonstrates the large potential in combining state-of-the-art computational hydrology with slope stability modeling in real-world cases

Chapter 8 The Status and Role of the alpine Cryosphere in Central Asia

The alpine cryosphere including snow, glaciers and permafrost are critical to water management in the Aral Sea Basin (ASB) and larger Central Asia (CA) under changing climate: as they store large amounts of water in its solid forms. Most cryospheric components in the Aral Sea Basin are close to melting point, and hence very vulnerable to a slight increase in air temperature with significant consequences to long-term water availability and to water resources variability and extremes. Current knowledge about different components of cryosphere and their connection to climate in the Basin and in the entire Central Asia, varies. While it is advanced in the topics of snow and glaciers, knowledge on permafrost it rather limited. Observed trends in runoff point in the direction of increasing water availability in July and August at least until mid-century and increasing possibility for water storage in reservoirs and aquifers. However, eventually this will change as glaciers waste away. Future runoff may change considerably after mid-century and start to decline if not compensated by increasing precipitation. Cryosphere monitoring systems are the basis for sound estimates of water availability and water-related hazards associated with snow, glaciers and permafrost. They require a well-distributed observational network for all cryospheric variables. Such systems need to be re-established in the Basin after the breakup of the Soviet Union in the early 1990s. This process is slowly emerging in the region. Collaboration between local operational hydro-meteorological services and academic sector, and with international research networks may improving the observing capabilities in high mountain regions of CA Asia in general and the ASB specifically

Using 81Kr and Noble Gases to Characterize and Date Groundwater and Brines in the Baltic Artesian Basin on the One-Million-Year Timescale

Analyses for $^{81}$Kr and noble gases on groundwater from the deepest aquifer system of the Baltic Artesian Basin (BAB) were performed to determine groundwater ages and uncover the flow dynamics of the system on a timescale of several hundred thousand years. We find that the system is controlled by mixing of three distinct water masses: Interglacial or recent meteoric water (\delta^{18}\text{O} \approx -10.4\unicode{x2030}) with a poorly evolved chemical and noble gas signature, glacial meltwater (\delta^{18}\text{O} \leq -18\unicode{x2030}) with elevated noble gas concentrations, and an old, high-salinity brine component (\delta^{18}\text{O} \geq -4.5\unicode{x2030}, \geq 90 \text{g Cl}^{-}/\text{L}) with strongly depleted atmospheric noble gas concentrations. The $^{81}$Kr measurements are interpreted within this mixing framework to estimate the age of the end-members. Deconvoluted $^{81}$Kr ages range from 300 ka to 1.3 Ma for interglacial or recent meteoric water and glacial meltwater. For the brine component, ages exceed the dating range of the ATTA 3 instrument of 1.3 Ma. The radiogenic noble gas components $^{4}$He* and $^{40}$Ar* are less conclusive but also support an age of > 1 Ma for the brine. Based on the chemical and noble gas concentrations and the dating results, we conclude that the brine originates from evaporated seawater that has been modified by later water-rock interaction. As the obtained tracer ages cover several glacial cycles, we discuss the impact of the glacial cycles on flow patterns in the studied aquifer system.Comment: Accepted for publication in Geochimica et Cosmochimica Act

Middle and Late Weichselian paraglacial and subglacial ervironments in the coastal plains of western Latvia

Tomas Saks Promocijas darbs: „Vidus Vislas un Vēlās Vislas laika paraglaciālie un zemledāja vides apstākļi Rietumlatvijas piekrastes līdzenumos” Anotācija Šajā pētījumā ir prezentēti Baltijas jūras stāvkrastu glaciotektonisko struktūru kartēšanas, glaciālo reljefa formu dešifrēšanas rezultāti un precizēta Rietumlatvijas pleistocēna slāņkopas augšējās daļas hronostratigrāfjija. Zem morēnas smilšainajos nogulumos ir veikti 13 jauni OSL datējumi. Glaciotektonisko struktūru kartēšanas rezultāti ļauj izšķirt trīs dažādus ledāja gultnes deformācijas veidus: (I) Atsegumu posmi, kas atbilst ledus mēļu centrālajai zonai, un kuriem ir raksturīgs mozaīkveida zemledāja deformācijas un morēnas akrēcijas sadalījums. (II) Atsegumu posmi, kas raksturojas ar kompresijas deformācijas struktūru sistēmu. Šie atsegumu posmi atbilst ledus mēļu marginālajām zonām, un ir šķērsgriezums bīdes sānu morēnām. (III) Atsegumu posmi, kuros nav zemledāja deformācijas pazīmes, kas ataino stagnanta ledāja apstākļus. Apriķu ledāja mēles gultnes dešifrēšanas rezultāti liecina, ka glaciālās reljefa formas un gultnes topogrāfija mainās strauji, līdz ar pamatiežu virsmas dziļuma un sastāva izmaiņām. OSL datēšanas rezultāti liecina par datētās slāņkopas uzkrāšanās laiku Vidus Vislas laikmetā, kas ļauj pārskatīt Rietumlatvijas pleistocēna slāņkopas augšējās daļas hronostratigrāfiju. Atslēgas vārdi: Diapīri, drumlini, sānu bīdes morēnas, OSL datējumi, Baltijas ledus lielplūsma. Latvijas Universitāte 19.06.2010Tomas Saks Promocijas darbs: „Middle and Late Weichselian paraglacial and subglacial environments in the coastal plains of western Latvia” Abstract In this thesis are presented results of: glacial geology and glaciotectonics of the Baltic sea coastal bluffs, mapping of the glacial landscape and established chronostratigraphy of the upper part of western Latvia Pleistocene sedimentary sequence. Results from the glaciotectonic structure reconstructions allow to differentiate three distinct subglacial deformation environments: (I) diapiric flow of the subglacial sediments induced by the changes of pore water pressure; (II) unidirectional compression deformation of the subglacial sediments; (III) areas of no subglacial deformation, resembling frozen to the bed ice conditions. Glacial bedform mapping results of the Apriķi glacial tongue bed allow to conclude that glacial landscape is changing abruptly along with the changes in bedrock composition and depth. Obtained OSL dates of the sandy sequence below upper till suggest Middle Weichselian age which allows reinterpreting the chronostratigraphy of the western Latvia Pleistocene sedimentary sequence upper part. Key words: Diapirs, drumlins, margin shear moraines, OSL dates, Baltic Ice Stream. Latvijas Universitāte 19.06.201

Personality and school performance: Incremental validity of self- and peer-ratings over intelligence

This paper examines the relationship of self and other-assessed personality with school grades in 255 (88 male) Croatian pupils. Conscientiousness was the strongest personality correlate of school grades for both self and peer-ratings. Grades were also negatively correlated with self-assessed Extraversion and Emotional Stability, and positively correlated with peer-ratings of Autonomy. When cognitive ability was partialled out correlations between personality and school grades showed little change, indicating that the effects of personality on academic performance were independent of intelligence. Hierarchical regressions indicated that personality accounted for unique variance in school grades: 18% by self- and 25% by peer-ratings. Self-ratings had only marginal incremental validity over peer-ratings in predicting school grades (3%), while incremental validity of peer- over self-ratings was larger (9%)

Hydrogeological model of the Baltic Artesian Basin

http://www.link.springer.com/article/10.1007%2Fs10040-013-0970-

Reconstructed Centennial Mass Balance Change for Golubin Glacier, Northern Tien Shan

Mass balance measurements for Golubin glacier in Northern Tien Shan, Kyrgyzstan, have been discontinuous over the last century, with significant data gaps. We provide a unique over 100-year-long mass balance series on daily resolution. We applied a temperature index model calibrated with glaciological measurements and validated with secular mass balances derived from independent length change observations. A comparison with other recent geodetic studies reveals good agreement. Golubin lost −0.16 ± 0.45 m w.e. a−1 from 1900/1901 to 2020/2021. From the long-term mass balance time series, we identify a shift to a more negative/less positive regime with time, with a steepening of the ablation and accumulation gradients, especially for the past two decades. We observe a parallel shift of the mass balance gradient accompanied by a rotation of the ablation gradient due to increased ablation at the glacier tongue and accumulation above the equilibrium line altitude. This tendency is believed to intensify in the future, affecting glaciers’ mass balance sensitivity to changes in atmospheric conditions and year-to-year variability and resulting in irregular melt water release feeding the rivers that provide water to Bishkek. These kinds of datasets are sparse for Tien Shan and, yet, indispensable to enhancing our understanding of glacier changes in High Mountain Asia

Glacier Runoff Variation Since 1981 in the Upper Naryn River Catchments, Central Tien Shan

Water resources in Central Asia strongly depend on glaciers, which in turn adjust their size in response to climate variations. We investigate glacier runoff in the period 1981-2019 in the upper Naryn basin, Kyrgyzstan. The basins contain more than 1,000 glaciers, which cover a total area of 776 km(2). We model the mass balance and runoff contribution of all glaciers with a simplified energy balance melt model and distributed accumulation model driven by ERA5 LAND re-analysis data for the time period of 1981-2019. The results are evaluated against discharge records, satellite-derived snow cover, stake readings from individual glaciers, and geodetic mass balances. Modelled glacier volume decreased by approximately 6.7 km(3) or 14%, and the majority of the mass loss took place from 1996 until 2019. The decreasing trend is the result of increasingly negative summer mass balances whereas winter mass balances show no substantial trend. Analysis of the discharge data suggests an increasing runoff for the past two decades, which is, however only partly reflected in an increase of glacier melt. Moreover, the strongest increase in discharge is observed in winter, suggesting either a prolonged melting period and/or increased groundwater discharge. The average runoff from the glacierized areas in summer months (June to August) constitutes approximately 23% of the total contributions to the basin's runoff. The results highlight the strong regional variability in glacier-climate interactions in Central Asia.ISSN:2296-665