ALBERT

Description: Effective conservation planning requires understanding and ranking threats to wildlife populations. We developed a Bayesian network model to evaluate the relative influence of environmental and anthropogenic stressors, and their mitigation, on the persistence of polar bears ( Ursus maritimus ). Overall sea ice conditions, affected by rising global temperatures, were the most influential determinant of population outcomes. Accordingly, unabated rise in atmospheric greenhouse gas (GHG) concentrations was the dominant influence leading to worsened population outcomes, with polar bears in three of four ecoregions reaching a dominant probability of decreased or greatly decreased by the latter part of this century. Stabilization of atmospheric GHG concentrations by mid-century delayed the greatly reduced state by ≈25 yr in two ecoregions. Prompt and aggressive mitigation of emissions reduced the probability of any regional population becoming greatly reduced by up to 25%. Marine prey availability, linked closely to sea ice trend, had slightly less influence on outcome state than sea ice availability itself. Reduced mortality from hunting and defense of life and property interactions resulted in modest declines in the probability of a decreased or greatly decreased population outcome. Minimizing other stressors such as trans-Arctic shipping, oil and gas exploration, and contaminants had a negligible effect on polar bear outcomes, although the model was not well-informed with respect to the potential influence of these stressors. Adverse consequences of loss of sea ice habitat became more pronounced as the summer ice-free period lengthened beyond four months, which could occur in most of the Arctic basin after mid-century if GHG emissions are not promptly reduced. Long-term conservation of polar bears would be best supported by holding global mean temperature to ≤ 2°C above preindustrial levels. Until further sea ice loss is stopped, management of other stressors may serve to slow the transition of populations to progressively worsened outcomes, and improve the prospects for their long-term persistence.

Description: ABSTRACT Multi-method geophysical investigations, accompanied by microclimatic measurements and vegetation mapping, were performed at an undercooled scree slope near Schladming (Austria) in the eastern Alps in order to detect, map and monitor mountain permafrost. The study site, at an elevation of 990 m asl, is one of the lowest-lying examples of a cold, undercooled scree slope in the Alps. Geophysical measurements with electrical resistivity tomography, ground-penetrating radar and seismic refraction indicate the presence of several isolated areas of frozen ground over a full year, far below the regional lower limit of mountain permafrost. Frozen sediments identified at shallow depths (beneath 1–3 m) were 5–20 m thick and ice-rich. Near-surface temperatures at the foot of the scree slope were strongly influenced by pronounced cooling. Vegetation mapping showed a dominance of cryophilic plant species. The results suggest that the scree slope is strongly influenced by the interplay of vegetation cover, ground thermal regime and the distribution of frozen sediments. Copyright © 2014 John Wiley & Sons, Ltd.

Description: The impact of global climate change on runoff components, especially on the type of overland flow, is of utmost significance. High-resolution temporal rainfall plays an important role in determining the hydrological response of quick runoff components. However, hydrological climate change scenario analyses with high temporal resolution are rare. This study investigates the impact of climate change on discharge peak events generated by rainfall, snowmelt, and soil-frost induced runoff using high-resolution hydrological modelling. The study area is Schäfertal catchment (1.44 km 2 ) in the lower Harz Mountains in central Germany. The WaSiM-ETH hydrological model is used to investigate the rainfall response of runoff components under near future (2021-2050) and far-distant future (2071-2100) climatic conditions. Disaggregated daily climate variables of WETTREG2010 SRES scenario A1B are used on a temporal resolution of 10-minute. Hydrological model parameter optimization and uncertainty analysis was conducted using the Differential Evolution Adaptive Metropolis (DREAM_(ZS)) uncertainty tool. The scenario results show that total runoff and interflow will increase by 30% and 29% in the near future and decrease by 15.9% and 14% in the far-distant future compared to the baseline scenario. In contrast, overland flow and the number and size of peak runoff will decrease moderately for the near future and drastically for the far-distant future compared to the baseline scenario. We found the strongest decrease for soil-frost induced discharge peaks at 79.6% in the near future and at 98.2% in the far-distant future scenario. It can be concluded that high-resolution hydrological modelling can provide detailed predictions of future hydrological regimes and discharge peak events of the catchment. Copyright © 2014 John Wiley & Sons, Ltd.

Description: Simulation of quick runoff components such as surface runoff and associated soil erosion requires temporal high-resolution rainfall intensities. However, these data are often not available because such measurements are costly and time consuming. Current rainfall disaggregation methods have shortcomings, especially in generating the distribution of storm events. The objectives of this study were to improve point rainfall disaggregation using a new magnitude-category rainfall disaggregation approach. The procedure is introduced using a coupled disaggregation approach (Hyetos and Cascade) for multisite rainfall disaggregation. The new procedure was tested with 10 long-term precipitation data sets of central Germany using summer and winter precipitation to determine seasonal variability. Results showed that dividing the rainfall amount into four daily rainfall magnitude categories (1-10, 11-25, 26-50, 〉 50 mm) improves the simulation of high rainfall intensity (convective rainfall). The Hyetos model category approach (Hyetos Cat ) with seasonal variation performs representative to observed hourly rainfall compared to without categories on each month. The mean absolute percentage accuracy of standard deviation for hourly rainfall is 89.7% in winter and 95.6% in summer. The proposed magnitude category method applied with the coupled Hyetos Cat -Cascade approach reproduces successfully the statistical behavior of local 10-minute rainfall intensities in terms of intermittency as well as variability. The RMSE performance statistics for disaggregated 10-minute rainfall depth ranges from 0.20-2.38 mm for summer and from 0.12-2.82 mm for the winter season in all categories. The coupled stochastic approach preserves the statistical self-similarity and intermittency at each magnitude category with a relatively low computational burden. This article is protected by copyright. All rights reserved.

Description: ABSTRACT Rock moisture during freeze-thaw events is a key factor for frost weathering. Data on moisture levels of natural rockwalls are scarce and difficult to obtain. To close this gap, we can benefit from the extensive knowledge of moisture-related phenomena in building materials, which is incorporated into simulation software, for example the WUFI® package of the Fraunhofer Institute of Building Physics. We applied and adapted this type of simulation to natural rockwalls to gain new insights on which moisture-related weathering mechanisms may be important under which conditions. This article is protected by copyright. All rights reserved. We collected the required input data on physical rock properties and local climate for two study areas in the Eastern European Alps with different elevation (Sonnblick, 3106 m a.s.l. and Johnsbach, 700 m a.s.l.) and different lithologies (gneiss and dolomite, respectively). From this data, moisture profiles with depth and fluctuations in the course of a typical year were calculated. The results were cross-checked with different thermal conditions for frost weathering reported in the literature (volumetric expansion and ice segregation theories). The analyses show that in both study areas the thresholds for frost cracking by volumetric expansion of ice (90% pore saturation, temperature 〈 -1 °C) are hardly ever reached (in one year only 0.07% of the time in Johnsbach and 0.4% at Sonnblick, mostly in north-exposed walls). The preconditions for weathering by ice segregation (-3 to -8 °C, 〉60% saturation) prevail over much longer periods; the time spent within this “frost cracking window” is also higher for north-facing sites. The influence of current climate warming will reduce effective frost events towards 2100; however the increase of liquid precipitation and rock moisture will promote weathering processes like ice segregation at least at the Sonnblick site. This article is protected by copyright. All rights reserved.

Description: The association between increasing water intensive land-cover, such as the use of turf grass and trees, and increasing water use is a growing concern for water-stressed arid cities. Appropriate regulatory measures addressing residential landscaping, such as those applied by Homeowner Associations (HOAs), may serve to reduce municipal water use, joining other water-use reducing measures under consideration by arid cities. This research assesses quantitatively the role that Covenants, Conditions, and Restrictions (CCRs) applied to landscaping by HOAs play on water consumption. Statistical comparisons and models of n=1,973 parcels in Goodyear, Arizona, USA, reveal that: HOA yards have less vegetation cover and those households use less peak-season water (July) than those households in non-HOA neighborhoods. This hold true even though the HOA CCRs regulate only the minimum required front-yard vegetation and most residents maintain more than the minimum vegetation level. Furthermore, front-yard landscaping tends to be mimicked in the backyard such that total yard landscaping tracks best with total household water use. Results of the study suggest that HOA landscaping regulations have the potential to reduce peak-season water use by up to 24% if CCRs were to set maximum vegetation regulations rather than minimum and if compliance were enforced. Lowering residential water consumption in this way potentially involves tradeoffs with the cooling effects of vegetation and its consequences on the urban heat island effect, on energy use, and on home values. This article is protected by copyright. All rights reserved.

Description: Fine-grained sediments constitute a major stressing factor for the aquatic ecosystem in the 15,000 km 2 Kharaa River catchment in Northern Mongolia. The objectives of this study were to identify the suspended sediment (SS) sources and quantify the sediment budget of the basin. Sediment sources were identified with the help of sediment tracing methods utilizing Be-7, Cs-137 and Pb-210 radionuclides. High resolution discharge data were used in combination with daily suspended solid measurements to calculate the SS budget. These calculations were compared with the monthly archive data on SS and discharge to investigate temporal load variations. In addition, the sediment budget model SedNet was used to estimate the SS budget and test its applicability in a cold semi-arid region. Results of the sediment tracing showed that riverbank erosion generates 74.5% of the suspended sediment load, whereas surface erosion contributes 21.7% and gully erosion only 3.8%. In the most intensely used agricultural tributary catchment Zagdelin Gol, upland erosion contributed only 12.7% to the total SS losses. The calculated mean annual sediment load for the years 1990-2002 was 20.3 kt⋅a -1 . The SedNet model computed SS export from the catchment in the same order of magnitude as measured data (16.2 kt⋅a -1 ). The results help to identify effective management measures to reduce sediment loads and mitigate its impact on the aquatic environment. Copyright © 2012 John Wiley & Sons, Ltd.

Description: A continuum-mechanical finite element model of skeletal muscle contractions that includes force enhancement based on actin-titin interaction is presented. This model can simulate muscles with a descending limb in the total force-length relation, which has previously led to unstable behaviour. The model predictions are in agreement with results of active stretch experiments. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)