<p>Available observations are often not sufficient as a basis for decision making in water management. Conceptual runoff models are frequently used as tools for a wide range of tasks to compensate the lack of measurements, e.g., to extend runoff series, compute design floods and predict the leakage of nutrients or the effects of a climatic change. Conceptual runoff models are practical tools, especially if the reliability in their predictions can be assessed. Testing of these models is usually based solely on comparison of simulated and observed runoff, although most models also simulate other fluxes and states. Such tests do not allow thorough assessment ofmodel-prediction reliability. In this thesis, two widespread conceptual models, the HBV modeland TOPMODEL, were tested using a catalogue of methods for model validation (defined as estimation of confidence in model simulations). The worth of multi-criteria validation forevaluating model consistency was emphasised. Both models were capable to simulate runoffadequately after calibration, whereas the performance for some of the other validation tests wasless satisfactory. The impossibility to identify unique parameter values caused large uncertainties in model predictions for the HBV model. The parameter uncertainty was reducedwhen groundwater levels were included into the calibration, whereas groundwater-levelsimulations were in weak agreement with observations when the model was calibrated againstonly runoff. The agreement of TOP-MODEL simulations with spatially distributed data was weak for both groundwater levels and the distribution of saturated areas. Furthermore, validation against hydrological common sense revealed weaknesses in the TOPMODEL approach. In summary these results indicated limitations of conceptual runoff models and highlighted the need for powarful validation methods. The use of such methods enables assessment of the reliability of model predictions. It also supports the further development of models by identification of weak parts and evalution of improvements.</p>

Collaborative Beamforming (CB) has been introduced in Wireless Sensor Networks (WSNs) context as a long-distance and power-efficient communication scheme. One challenge for CB is the randomness of sensor node locations where different network realizations result in different CB beampatterns. First, we study the effect of sensor node spatial distribution on the CB beampattern. The characteristics of the CB beampattern are derived for circular Gaussian distributed sensor nodes and compared with the case of uniform distributed sensor nodes. It is shown that the mainlobe behavior of the CB beampattern is essentially deterministic. This suggests that the average beampattern characteristics are suitable for describing the mainlobe of a sample beampattern. However, the CB beampattern sidelobes are random and highly depends on the particular sensor node locations. Second, we introduce the multi-link CB and address the problem of random sidelobes where high level sidelobes can cause unacceptable interference to unintended Base Stations or Access Points (BSs/APs). Centralized sidelobe control techniques are impractical for distributed sensor nodes because of the associated communication overhead for each sensor node. Therefore, we propose a node selection scheme as an alternative to the centralized sidelobe control which aims at minimizing the interference at unintended BSs/APs. Our algorithm is based on the use of the inherent randomness of the channels and a low feedback that approves/rejects tested random node combinations. The performance of the proposed algorithm is analyzed in terms of the average number of trials and the achievable interference suppression and transmission rate. Finally, we study CB with power control aiming at prolonging the lifetime of a cluster of sensor nodes in the WSN. The energy available at different sensor nodes may not be the same since different sensor nodes may perform different tasks and not equally frequently. CB with power control can be used to balance the individual sensor nodes' lifetimes. Thus, we propose a distributed algorithm for CB with power control that is based on the Residual Energy Information (REI) at each sensor node while achieving the required average SNR at the BS/AP. The effectiveness of the proposed CB with power control is illustrated by simulations. / Communications

Available observations are often not sufficient as a basis for decision making in water management. Conceptual runoff models are frequently used as tools for a wide range of tasks to compensate the lack of measurements, e.g., to extend runoff series, compute design floods and predict the leakage of nutrients or the effects of a climatic change. Conceptual runoff models are practical tools, especially if the reliability in their predictions can be assessed. Testing of these models is usually based solely on comparison of simulated and observed runoff, although most models also simulate other fluxes and states. Such tests do not allow thorough assessment ofmodel-prediction reliability. In this thesis, two widespread conceptual models, the HBV modeland TOPMODEL, were tested using a catalogue of methods for model validation (defined as estimation of confidence in model simulations). The worth of multi-criteria validation forevaluating model consistency was emphasised. Both models were capable to simulate runoffadequately after calibration, whereas the performance for some of the other validation tests wasless satisfactory. The impossibility to identify unique parameter values caused large uncertainties in model predictions for the HBV model. The parameter uncertainty was reducedwhen groundwater levels were included into the calibration, whereas groundwater-levelsimulations were in weak agreement with observations when the model was calibrated againstonly runoff. The agreement of TOP-MODEL simulations with spatially distributed data was weak for both groundwater levels and the distribution of saturated areas. Furthermore, validation against hydrological common sense revealed weaknesses in the TOPMODEL approach. In summary these results indicated limitations of conceptual runoff models and highlighted the need for powarful validation methods. The use of such methods enables assessment of the reliability of model predictions. It also supports the further development of models by identification of weak parts and evalution of improvements.

The assessment of volatile organic compounds (VOCs) has become an area of particular interest in the field of atmospheric pollution due to their adverse health and environmental effects. This study is aimed to identify, quantify and characterize VOC in different urban areas and industrial areas in Bursa. The spatial distribution, seasonal variation as well as health risks assessment of VOC were discussed. Air samples were collected by means of sorbent passive sampling at over 50 sampling points in Bursa and analyzed by GC-thermal desorption. A total of seven weekly measurement periods were completed across the city center from 2005 to 2007. The source of VOC was apportioned with the commonly used receptor model, namely Factor Analysis. Motor vehicles and industrial solvent usage are the most abundant VOC sources to contribute to urban atmosphere in Bursa, 63% and 20%, respectively. The health risks of VOC were also evaluated. The questionnaire was filled out by selected people living in Bursa to obtain time-activity pattern for health risk assessment. Lifetime cancer risks were estimated with the measured VOC data. All the statistical parameters used to represent cancer risks for the selected compounds exceeded the stated level. Benzene had the highest adverse health effect among these compounds according to USEPA (2009) calculation with the mean cancer risk 3x10-4. In addition to intensive field sampling campaigns conducted in Bursa, the VOC measurement were completed for a period of six months to evaluate uptake rate of VOC in Ankara. Uptake rate equations depending on relative humidity and wind speed were developed for 25 VOCs.

Information about large mammals in Turkey usually does not go further than species lists or annual counts of particular species such as the wild goat. Camera trapping is a very useful technique to overcome this deficiency by gathering information about species presence, numbers, habitat use and behavior. Hence, a one year long camera trap study was conducted to demonstrate the diversity, activity, distribution patterns, habitat preferences and interspecific interactions of medium and large mammals in a 148 km2 large pine woodland near Ankara. Brown bear (Ursus arctos), wolf (Canis lupus), Eurasian lynx (Lynx lynx), golden jackal (Canis aureus), jungle cat (Felis chaus), red fox (Vulpes vulpes), Eurasian badger (Meles meles), stone marten (Martes foina), red deer (Cervus elaphus), wild boar (Sus scrofa), brown hare (Lepus europaeus), Caucasian squirrel (Sciurus anomalus) and southern white-breasted hedgehog (Erinaceus concolor) were the 13 mammal species captured during the study. Spatial segregation was observed among canid species indicating intraguild competition and competitive exclusion. Prey-predator interactions were documented at both spatial and temporal scales between wolves, deer and wild boars. Red deer showed seasonal and sex differences in activity patterns that appeared to be influenced by wolf predation risk. The presence of two felids unknown to the local people were revealed by camera trapping, showing the utility of this technique for such secretive and rare species. However, the low encounter rates for particular species such as lynx, brown bear and jungle cat indicated the importance of the length of study. Based on various evidence, resident adult population sizes were estimated for wolf (2-5), Eurasian lynx (2-4), brown bear (0-2) and jungle cat (2-3). The study showed that lynx can exist in high densities in a relatively small area when prey species are abundant. This study area hosted a rich mammal fauna in spite of human activities such as livestock grazing, logging and hunting. A relatively intact ecosystem, high altitudinal and habitat diversity, and a positive attitude of local people are believed to be the reasons of this observed high diversity.

Nors hidromechaninio ežerų valymo darbai vykdomi jau daugelį metų, iki šiol nėra aišku, kaip pasikeičia ežero aplinkosauginė būklė po jo išvalymo, o Lietuvos ir kitų šalių mokslinėje literatūroje informacijos apie valymo sąlygotus metalų ir metaloidų pasiskirstymo dugno nuosėdose pokyčius yra stebėtinai mažai. Disertacijos tyrime buvo taikoma kompleksinė šių pokyčių vertinimo sistema, pasitelkiant ne tik išsamius geocheminius lauko ir laboratorinius tyrimus, bet ir matematinę statistinę analizę bei erdvinę duomenų prognozę ir interpoliaciją. Tyrimų ir analizės rezultatai parodė, kad hidromechaninis ežero valymas sąlygoja nagrinėjamų metalų ir metaloidų kiekių pokyčius ir jų persiskirstymą dugno nuosėdose, kuris yra savitas atskiriems cheminiams elementams, todėl siekiant nustatyti valymo darbų įtaką būtina naudoti indikatorius, leidžiančius įvertinti bendro, kumuliacinio nuosėdų užterštumo lygio pokyčius visų nagrinėjamų elementų atžvilgiu. Vieno iš tokių indikatorių – suminio užterštumo rodiklio Zd verčių statistinė analizė ir erdvinė interpoliacija leido ne tik nustatyti statistiškai patikimą hidromechaninio ežero valymo įtakotą metalų ir metaloidų pokyčių reikšmingumą naujai susiformavusiame paviršiniame dugno nuosėdų sluoksnyje, bet ir pademonstruoti erdvinį šių elementų perskirstymą dugno paviršiaus plote. Disertacijoje pateikiama informacija yra ypač aktuali vertinant Lietuvos ežerų būklę, planuojant ežerų dugno nuosėdų šalinimo darbus ir nustatant jų tikslingumą. / Although hydromechanical lake remediation projects have been carried out over several decades, there still is a lack of evidence about the changes in environmental status after such projects, while scientific literature regarding redistribution of metals and metalloids caused by hydromechanical bottom sediment removal is especially scarce both in Lithuania and in other countries. Research of the dissertation consisted not only of extensive geochemical field work and laboratory analysis, but also methods of mathematical statistics and spatial interpolation. Results of the research and their analysis allowed to conclude that hydromechanical lake remediation results in changes of the contents of metals and metalloids of interest and their spatial redistribution in lake bottom sediments, which are specific to each metal and metalloid, thus cumulative indicators should be used to assess overall changes in sediment quality of remediated lakes. Calculation and statistical analysis of on of such indicators - total sediment contamination index (Zd) and surface interpolation of its values allowed to evaluate statistical significance of changes in contamination degree of the newly formed surface sediment layer and to assess cumulative spatial redistribution of metals and metalloids caused by hydromechanical lake remediation. Data provided in the dissertation is especially significant in preparation and design of future sediment removal projects and in determining their feasibility.

Although hydromechanical lake remediation projects have been carried out over several decades, there still is a lack of evidence about the changes in environmental status after such projects, while scientific literature regarding redistribution of metals and metalloids caused by hydromechanical bottom sediment removal is especially scarce both in Lithuania and in other countries. Research of the dissertation consisted not only of extensive geochemical field work and laboratory analysis, but also methods of mathematical statistics and spatial interpolation. Results of the research and their analysis allowed to conclude that hydromechanical lake remediation results in changes of the contents of metals and metalloids of interest and their spatial redistribution in lake bottom sediments, which are specific to each metal and metalloid, thus cumulative indicators should be used to assess overall changes in sediment quality of remediated lakes. Calculation and statistical analysis of on of such indicators - total sediment contamination index (Zd) and surface interpolation of its values allowed to evaluate statistical significance of changes in contamination degree of the newly formed surface sediment layer and to assess cumulative spatial redistribution of metals and metalloids caused by hydromechanical lake remediation. Data provided in the dissertation is especially significant in preparation and design of future sediment removal projects and in determining their feasibility. / Nors hidromechaninio ežerų valymo darbai vykdomi jau daugelį metų, iki šiol nėra aišku, kaip pasikeičia ežero aplinkosauginė būklė po jo išvalymo, o Lietuvos ir kitų šalių mokslinėje literatūroje informacijos apie valymo sąlygotus metalų ir metaloidų pasiskirstymo dugno nuosėdose pokyčius yra stebėtinai mažai. Disertacijos tyrime buvo taikoma kompleksinė šių pokyčių vertinimo sistema, pasitelkiant ne tik išsamius geocheminius lauko ir laboratorinius tyrimus, bet ir matematinę statistinę analizę bei erdvinę duomenų prognozę ir interpoliaciją. Tyrimų ir analizės rezultatai parodė, kad hidromechaninis ežero valymas sąlygoja nagrinėjamų metalų ir metaloidų kiekių pokyčius ir jų persiskirstymą dugno nuosėdose, kuris yra savitas atskiriems cheminiams elementams, todėl siekiant nustatyti valymo darbų įtaką būtina naudoti indikatorius, leidžiančius įvertinti bendro, kumuliacinio nuosėdų užterštumo lygio pokyčius visų nagrinėjamų elementų atžvilgiu. Vieno iš tokių indikatorių – suminio užterštumo rodiklio Zd verčių statistinė analizė ir erdvinė interpoliacija leido ne tik nustatyti statistiškai patikimą hidromechaninio ežero valymo įtakotą metalų ir metaloidų pokyčių reikšmingumą naujai susiformavusiame paviršiniame dugno nuosėdų sluoksnyje, bet ir pademonstruoti erdvinį šių elementų perskirstymą dugno paviršiaus plote. Disertacijoje pateikiama informacija yra ypač aktuali vertinant Lietuvos ežerų būklę, planuojant ežerų dugno nuosėdų šalinimo darbus ir nustatant jų tikslingumą.

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Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 5 uppsatser.