An approach to combine radar and gauge based rainfall data under consideration of their qualities in low mountain ranges of Saxony

An approach to combine gauge and radar data and additional quality information is presented. The development was focused on the improvement of the diagnostic for temporal (one hour) and spatial (1×1 km<sup>2</sup>) highly resolved precipitation data. The method is embedded in an online tool and was applied to the target area Saxony, Germany. The aim of the tool is to provide accurate spatial rainfall estimates. The results can be used for rainfall run-off modelling, e.g. in a flood management system. <br><br> Quality information allows a better assessment of the input data and the resulting precipitation field. They are stored in corresponding fields and represent the static and dynamic uncertainties of radar and gauge data. Objective combination of various precipitation and quality fields is realised using a cost function. <br><br> The findings of cross validation reveal that the proposed combination method merged the benefits and disadvantages of interpolated gauge and radar data and leads to mean estimates. The sampling point validation implies that the presented method slightly overestimated the areal rain as well as the high rain intensities in case of convective and advective events, while the results of pure interpolation method performed better. In general, the use of presented cost function avoids false rainfall amount in areas of low input data quality and improves the reliability in areas of high data quality. It is obvious that the combined product includes the small-scale variability of radar, which is seen as the important benefit of the presented combination approach. Local improvements of the final rain field are possible due to consideration of gauges that were not used for radar calibration, e.g. in topographic distinct regions

Use of past precipitation data for regionalisation of hourly rainfall in the low mountain ranges of saxony, germany

Within the context of flood forecasting we deal with the improvement of regionalisation methods for the generation of highly resolved (1 h, 1x1km(2)) precipitation fields, which can be used as input for rainfall-runoff models or for verification of weather forecasts. Although radar observations of precipitation are available in many regions, it might be necessary to apply regionalisation methods near real-time for the cases that radar is not available or observations are of low quality. The aim of this paper is to investigate whether past precipitation information can be used to improve regionalisation of rainfall. Within a case study we determined typical precipitation Background-Fields (BGF) for the mountainous and hilly regions of Saxony using hourly and daily rain gauge data. Additionally, calibrated radar data served as past information for the BGF generation. For regionalisation of precipitation we used de-trended kriging and compared the results with another kriging based regionalisation method and with Inverse Distance Weighting (IDW). The performance of the methods was assessed by applying cross-validation, by inspection and by evaluation with rainfall-runoff simulations. The regionalisation of rainfall yielded better results in case of advective events than in case of convective events. The performance of the applied regionalisation methods showed no significant disagreement for different precipitation types. Cross-validation results were rather similar in most cases. Subjectively judged, the BGF-method reproduced best the structures of rain cells. Precipitation input derived from radar or kriging resulted in a better matching between observed and simulated flood hydrographs. Simple techniques like IDW also deliver satisfying results in some occasions. Implementation of past radar data into the BGF-method rendered no improvement, because of data shortages. Thus, no method proved to outperform the others generally. The decision, which method is appropriate for an event, should be made objectively using cross-validation, but also subjectively, using the expert knowledge of the forecaster.BMBF/0330700

A modeling framework to assess water and nitrate balances in the Western Bug river basin, Ukraine

The objective of this study was to assess the utility of the eco-hydrological SWAT model (Soil and Water Assessment Tool, Arnold et al., 1998) for representing water balance and nitrate fluxes given limited input and calibration data. The investigated catchment is located in Western Ukraine with an area of approximately 2616 km². Land use is currently dominated by agriculture with significant areas of pasture, and has undergone a high degree of changes in land-use and agricultural practice since the end of the Soviet Union. Model application produced a fitted water balance (calibration: <i>R</i>² = 0.52, NS = 0.46; validation: <i>R</i>² = 0.47, NS = 0.51) and plausible ranges and dynamics of nitrate in stream loadings. Groundwater parameters were found to be highly sensitive. The results indicate that SWAT is an appropriate tool for water resource investigations in the Western Bug catchment, and can provide a useful tool for further eco-hydrologic research in the region (i.e. diffuse pollution impacts)

Climate analysis as a basis for a sustainable water management at the Lusatian Neisse

Current and future climate conditions and their impact on water balance, ecosystems, air quality and bio and agro-climatology were investigated in the region of the Lusatian Neisse within the two EU -projects – NEYMO and KLAPS. This work focuses on the climate analysis of the region at the German-Polish border as a preliminary step for a hydrological analysis of current and future conditions. Observed climatological data were processed and analysed using the indicators air temperature, precipitation, sunshine duration, potential evapotranspiration and the climatic water balance (CWB). The latter defines the difference between precipitation and potential evapotranspiration and is a measure for the climatological water availability in the region. Observations were used to statistically downscale data from Global Circulation Models under various scenarios regarding greenhouse gas emissions (A1B, RCP 2.6, RCP 8.5) and applying the WETTREG-method for regionalization. In total, 50 climate projections for periods up until the end of the 21st century were analysed, with the application of the mentioned indicators. For the period 1971-2010, increasing trends of temperature, precipitation, sunshine duration and potential evapotranspiration were found. This leads to a reduced CWB in the summer half-year (SHY), which could be partly compensated by an increase in the winter half-year (WHY). Trends of temperature, sunshine duration and potential evapotranspiration remain positive for the far future (2071-2100), but precipitation decreases. These climatic conditions aggravate water availability, especially in the SHY. Impacts on water management are very probable and were therefore further investigated in the NEY MO project that applied hydrological models

Effect of Aquatic Plant Patches on Flow and Sediment Characteristics: The Case of Callitriche platycarpa and Elodea nuttalli

OCLC: 1050002872International audienceThis book presents selected contributions of the 34th International School of Hydraulics that was held in May 2015 in Zelechów, Poland. It gives an overview about the state-of-the-art in environmental hydraulics. A special emphasis is put upon physical, biochemical and ecological processes that act at interfaces in natural surface water bodies but also other important hydraulic problems are considered. The achievements of well-known researchers from all over the world as well as the results obtained by young researchers, among others within a Marie Curie funded Initial Training Network, led by the University of Padua (HYTECH - HYdrodynamic Transport at Ecologically Critical Heterogeneous Interfaces) are gathered in this volume

On the role of mechanical stress in the chemical ordering of nanoalloys

Metallic alloy clusters at equilibrium display an inhomogeneous stress field which may contribute to the chemical ordering and segregation properties. We use the example of cuboctahedral and icosahedral Au-Pd clusters with the same size to compare these properties in systems displaying moderately and highly inhomogeneous stress fields. Metropolis Monte Carlo simulations in the semi-grand canonical ensemble are used with an empirical potential to predict equilibrium configurations. Pressure maps are used to estimate stress on each atom. It is found that when the stress field is moderately inhomogeneous, ordering is dominantly driven by thermodynamic forces. In icosahedral clusters, ordering is found to be the consequence of a balance where thermodynamic forces and mechanical stress may conflict or reinforce each other. Order-disorder transitions are smoother in the systems with higher stress inhomogeneity and it is conjectured that, in icosahedral clusters, disorder may nucleate in the central core. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012.SCOPUS: ar.jinfo:eu-repo/semantics/inPres