Spatial and temporal variability of precipitation in Serbia for the period 1961–2010     

Milovanović  Boško  Schuster  Phillip  Radovanović  Milan  Vakanjac  Vesna Ristić  Schneider  Christoph 《Theoretical and Applied Climatology》2017,130(1-2):687-700

Monthly, seasonal and annual sums of precipitation in Serbia were analysed in this paper for the period 1961–2010. Latitude, longitude and altitude of 421 precipitation stations and terrain features in their close environment (slope and aspect of terrain within a radius of 10 km around the station) were used to develop a regression model on which spatial distribution of precipitation was calculated. The spatial distribution of annual, June (maximum values for almost all of the stations) and February (minimum values for almost all of the stations) precipitation is presented. Annual precipitation amounts ranged from 500 to 600 mm to over 1100 mm. June precipitation ranged from 60 to 140 mm and February precipitation from 30 to 100 mm. The validation results expressed as root mean square error (RMSE) for monthly sums ranged from 3.9 mm in October (7.5% of the average precipitation for this month) to 6.2 mm in April (10.4%). For seasonal sums, RMSE ranged from 10.4 mm during autumn (6.1% of the average precipitation for this season) to 20.5 mm during winter (13.4%). On the annual scale, RMSE was 68 mm (9.5% of the average amount of precipitation). We further analysed precipitation trends using Sen’s estimation, while the Mann-Kendall test was used for testing the statistical significance of the trends. For most parts of Serbia, the mean annual precipitation trends fell between −5 and +5 and +5 and +15 mm/decade. June precipitation trends were mainly between −8 and +8 mm/decade. February precipitation trends generally ranged from −3 to +3 mm/decade.

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Estimating water balance components in irrigated agriculture using a combined approach of soil moisture and energy balance monitoring,and numerical modelling     

Stephan Schulz  Rike Becker  Juan Carlos Richard-Cerda  Muhammad Usman  Tim aus der Beek  Ralf Merz  Christoph Schüth 《水文研究》2021,35(3):e14077

Information on water balance components such as evapotranspiration and groundwater recharge are crucial for water management. Due to differences in physical conditions, but also due to limited budgets, there is not one universal best practice, but a wide range of different methods with specific advantages and disadvantages. In this study, we propose an approach to quantify actual evapotranspiration, groundwater recharge and water inflow, i.e. precipitation and irrigation, that considers the specific conditions of irrigated agriculture in warm, arid environments. This approach does not require direct measurements of precipitation or irrigation quantities and is therefore suitable for sites with an uncertain data basis. For this purpose, we combine soil moisture and energy balance monitoring, remote sensing data analysis and numerical modelling using Hydrus. Energy balance data and routine weather data serve to estimate ET₀. Surface reflectance data from satellite images (Sentinel-2) are used to derive leaf area indices, which help to partition ET₀ into energy limited evaporation and transpiration. Subsequently, first approximations of water inflow are derived based on observed soil moisture changes. These inflow estimates are used in a series of forward simulations that produce initial estimates of drainage and ET_act, which in turn help improve the estimate of water inflow. Finally, the improved inflow estimates are incorporated into the model and then a parameter optimization is performed using the observed soil moisture as the reference figure. Forward simulations with calibrated soil parameters result in final estimates for ET_act and groundwater recharge. The presented method is applied to an agricultural test site with a crop rotation of cotton and wheat in Punjab, Pakistan. The final model results, with an RMSE of 2.2% in volumetric water content, suggest a cumulative ET_act and groundwater recharge of 769 and 297 mm over a period of 281 days, respectively. The total estimated water inflow accounts for 946 mm, of which 77% originates from irrigation.  相似文献   

Advancing tsunami risk assessment by improving spatio-temporal population exposure and evacuation modeling     

Sergio Freire  Christoph Aubrecht  Stephanie Wegscheider 《Natural Hazards》2013,68(3):1311-1324

Tsunamis are among the most destructive and lethal of coastal hazards. These are time-specific events, and despite directly affecting a narrow strip of coastline, a single occurrence can have devastating effects and cause massive loss of life, especially in urbanized coastal areas. In this work, in order to consider the time dependence of population exposure to tsunami threat, the variation of spatio-temporal population distribution in the daily cycle is mapped and analyzed in the Lisbon Metropolitan Area. High-resolution daytime and nighttime population distribution maps are developed using ‘intelligent dasymetric mapping,’ that is, applying areal interpolation to combine best-available census data and statistics with land use and land cover data. Workplace information and mobility statistics are considered for mapping daytime distribution. In combination with a tsunami hazard map, information on infrastructure, land use and terrain slope, the modeled population distribution is used to assess people’s evacuation speed, applying a geospatial evacuation modeling approach to the city of Lisbon. The detailed dynamic population exposure assessment allows producing both daytime and nighttime evacuation time maps, which provide valuable input for evacuation planning and management. Results show that a significant amount of population is at risk, and its numbers increase dramatically from nighttime to daytime, especially in the zones of high tsunami flooding susceptibility. Also, full evacuation can be problematic in the daytime period, even if initiated immediately after a major tsunami-triggering earthquake. The presented approach greatly improves tsunami risk assessment and can benefit all phases of the disaster management process.  相似文献   

Laminated carbonate deposits in Roman aqueducts: Origin,processes and implications     

Gül Sürmelihindi  Cees W. Passchier  Christoph Spötl  Paul Kessener  Michel Bestmann  Dorrit E. Jacob  Orhan N. Baykan 《Sedimentology》2013,60(4):961-982

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Evaluation of noise annotation lines: using noise to represent thematic uncertainty in maps     

Christoph Kinkeldey  Jennifer Mason  Alexander Klippel  Jochen Schiewe 《制图学和地理信息科学》2013,40(5):430-439

Noise annotation lines are a promising technique to visualize thematic uncertainty in maps. However, their potential has not yet been evaluated in user studies. In two experiments, we assessed the usability of this technique with respect to a different number of uncertainty levels as well as the influence of two design aspects of noise annotation lines: the grain and the width of the noise grid. We conducted a web-based study utilizing a qualitative comparison of 2 areas in 150 different maps. We recruited participants from Amazon Mechanical Turk with the majority being nonexperts with respect to the use of maps. Our findings suggest that for qualitative comparisons of “constant uncertainty” (i.e., constant uncertainty per area) in thematic maps, noise annotation lines can be used for up to six uncertainty levels. During comparison of four, six, and eight levels, the different designs of the technique yielded significantly different accuracies. We propose to use the “large noise width, coarse grain” design that was most successful. For “mixed uncertainty” (i.e., uncertainty is not constant per area) we observed a significant decrease in accuracy, but for four levels the technique can still be recommended. This article is a follow-up to our conference paper reporting on preliminary results of the first of the two experiments.  相似文献   

Seasonal to decadal forcing of high water level percentiles in the German Bight throughout the last century     

Sönke Dangendorf  Christoph Mudersbach  Jürgen Jensen  Ganske Anette  Hartmut Heinrich 《Ocean Dynamics》2013,63(5):533-548

For the purpose of coastal planning and management, especially under changing climatic conditions, enhanced knowledge about the evolution of extreme sea levels in the past, present, and future is required. This paper presents statistical analyses of high seasonal water level percentiles of 13 tide gauges in the German Bight, spanning over a period of up to 109 years throughout the twentieth and twenty-first centuries. Seasonal and annual high percentile time series of water levels were investigated in comparison to the mean sea level (MSL) for changes on seasonal, inter-annual, and decadal timescales. While throughout the first half of the twentieth century extreme water levels generally followed changes in MSL, during the second half of the century, linear extreme sea level trends exceeded those in MSL in the order of 9–64 cm per century. The largest, although insignificant, contribution to the magnitude of these trends occurs in the winter season (January to March), while smaller but, due to the generally lower atmospheric variability, significant changes are observed during spring (April to June). The observed multi-decadal trends are generally in good agreement with multi-decadal trends in the corresponding percentiles of local zonal surface winds. Only small parts of the trends remain unexplained. It is suggested that these remaining trends result from modifications in the local tidal regime. For the aspects of coastal planning, the findings clarify that in the German Bight, in addition to changes in MSL, potential changes in storminess and in the tidal regime significantly contribute to the development of extreme water levels. Since these factors have influenced the characteristic of extremes throughout the recent past, they also have to be taken into account when estimating design water levels for, e.g., dikes (in a warming climate) under changing greenhouse gas emissions.  相似文献   

Large-scale diffractive X-ray telescopes     

Christoph Braig  Peter Predehl 《Experimental Astronomy》2006,21(2):101-123

Capabilities of large-scale diffractive X-ray telescopes are discussed. Based on purely transmissive optics, an angular resolution of at least 10⁻³ arcsec will be achieved using detection techniques with spectral selectivities in the sub-eV range for short focal distances of few 10² km. We use stepped versions of Fresnel apertures made of plastic foils, divided into optically independent segments by two alternative schemes. It is shown that point source sensitivities near 10³ cm² keV require lens diameters up to 30 m. Like monochromatic objectives, properly shaped dual- or multiband telescopes may be tuned over several keV. Such configurations are made of partial Fresnel lenses with coinciding focal distances and similar spot sizes and compete well with single-band analogues.  相似文献   

A coupled transport and reaction model for long column experiments simulating bank filtration     

Christoph Horner  Ekkehard Holzbecher  Gunnar Nützmann 《水文研究》2007,21(8):1015-1025

Within the scope of the interdisciplinary Natural and Artificial Systems for Recharge and Infiltration research project dealing with riverbank filtration processes at the Berlin water works, a semi‐technical column experiment has been ongoing since January 2003. Here, a 30 m long soil column is infiltrated with surface water sampled from Lake Tegel (Berlin, Germany) under saturated flow conditions. Changes in pore water hydrochemistry sampled on 21 non‐equidistant distributed points are verified by coupled transport and reaction modelling. The objective of reactive transport modelling was to identify the main biogeochemical processes within the soil column during the flushing experiment as a conceptual model for riverbank filtration. Modelling was done with a combination of MATLAB and PHREEQC. The main processes identified are: (1) biogeochemical degradation due to interaction of natural surface water with the soil matrix; (2) continuous dissolution of refractory air bubbles from the soil column matrix. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

GIS Teacher Training: Empirically-Based Indicators of Effectiveness     

Steffen Höhnle  Janis Fögele  Rainer Mehren  Jan Christoph Schubert 《The Journal of geography》2016,115(1):12-23

In spite of various actions, the implementation of GIS (geographic information systems) in German schools is still very low. In the presented research, teaching experts as well as teaching novices were presented with empirically based constraints for implementation stemming from an earlier survey. In the process of various group discussions, the participants developed ideas for overcoming the constraints in the field of continuing teacher education among others. These ideas were used to create empirically based strategies for the future design of training activities in continuing education of teachers while taking these constraints into account. These strategies were later validated externally by comparing them to empirical findings on effects of training activities in continuing teacher education in general and empirical findings on GIS implementation from other studies.  相似文献   

Diatom assemblages reveal regional-scale differences in lake responses to recent climate change at the boreal-tundra ecotone,Manitoba, Canada     

Avery L. C. Shinneman  Charles E. Umbanhowar  Mark B. Edlund  William O. Hobbs  Philip Camill  Christoph Geiss 《Journal of Paleolimnology》2016,56(4):275-298

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