Master of Science / Department of Biological & Agricultural Engineering / Danny H. Rogers / Center pivot irrigation systems are used in crop production across the state of Kansas. The American Society of Agricultural and Biological Engineers (ASABE) standard on uniformity testing of a center pivot system calls for collectors to be used to measure the water depth emitted by the irrigation system. The standard was designed without specially considering the low pressure sprinklers now commonly used on center pivot systems; the recommended collectors may not accurately measure the applied depth from these sprinklers. The collector size effect on measured water depth and measured depth variability was studied for spinning plate, fixed plate, and wobbling plate sprinkler systems. Five different collector sizes (C2 (5.5 cm), C4 (10.0 cm), C6 (14.8 cm), C8 (20.0 cm), and C10 (27.4 cm)) were studied using four 5x5 Latin squares. Each collector’s water depth was measured and statistically analyzed. Two analysis of variance (ANOVA) tests of the collector size effect were reported. Past experimental results were compared to this experiment’s results. The ANOVA for the measured water depth reported no collector size effect for the spinning plate and wobbling plate systems. The ANOVA of the variability of measured depths showed significant differences between collector sizes for the spinning plate system but not for the wobbling plate system. Previous studies of spinning plate and wobbling plate systems reported acceptable variability for all collector sizes. Although some collector sizes measured significantly different mean depths, the numerical difference in mean depths was small. Any studied collector size could be used to measure the water depth of wobbling plate systems, but the C4 collector is ideal. C4 and C6 collectors are ideal for measuring spinning plate systems. Significant differences between measured depths were reported for the fixed plate system. The C10 measured significantly lower water depths than all other collectors, and the C4 collector measured lower depths than the C2 and C8 collectors. The variability of mean depths was similar and high for all collector sizes. Previous experiments also indicated that different collector sizes measured different depths and had high variability of depth measurements for the fixed plate sprinkler systems. The distinct stream pattern provides a challenge for accurately measuring the water depth with these collector sizes; other methods of measuring uniformity should be considered for fixed plate sprinklers.

Previous works have validated the concept of a microwave rain gauge that operates as follows. With a microwave Doppler motion sensor, the Doppler shift created by falling rain drops is measured. One can then relate the corresponding fall velocity to rain rate. However, the available Doppler motion sensors are lacking in several aspects. Here we address the important electronic design and signal processing considerations related to a microwave-based rain gauge.

To compensate the strong Troposheric impairments caused in the Ka frequency band, it is necessary to use Fade Mitigation Techniques. To develop and validate such techniques, time series of rain attenuation are needed. Nevertheless, these data are difficult to obtain. An alternative to using real rain attenuation time series is to develop a model of rain rate time series synthesizer. Nevertheless, real rain rate time series are needed to develop and validate this model. The aim of this internship is to provide real rain rate data useful for the development, parameterization and validation of this new model. In the first part of this report, different rain rate computation methods will be presented. Then, real data from a rain gauge located at Onera premises in Toulouse will be processed according to the presented methods and to a novel one. Results will be statistically analysed and finally a study of both the error of the methods and the uncertainty of the experimental devices and tools will be carried out. / <p>Validerat; 20120514 (anonymous)</p>

The United States Weather Bureau had published Technical Paper No. 40 (TP-40) in 1961 which provides a rainfall atlas for the United States. These rainfall frequencies have been used by engineers throughout the United States including Jefferson Parish, Louisiana. Rainfall from Audubon and the New Orleans International Airport rain gauge stations were used with the Log Pearson Method to provide rainfall frequency for Jefferson Parish, Louisiana. The results from the frequency rainfall that were developed for this research along with the current Jefferson Parish design storm rainfall were applied to a typical urban development to evaluate the extent of flooding.

Debris flows occur frequently in remote areas of Great Smoky Mountains National Park, Tennessee. Rainfall gauges are not adequate for modeling infiltration required for triggering debris flows. Weather radar, providing frequently updated, continuous coverage, is a valuable tool for estimating rainfall intensity, duration, runoff, and infiltration. Daily rainfall from a sole gauge was compared with hourly rainfall from the Digital Precipitation Array weather radar product to model infiltration on August 5, 2012, the day before a debris flow was known to have occurred in the 91-km2West Prong Little Pigeon River watershed. Additionally, both gauge and radar data were used for rainfall-runoff-infiltration modeling for a 42-day period in July and August 2012. Runoff and infiltration were simulated using the conventional semi-distributed hydrological model HEC-HMS. A local bias correction of radar rainfall at the gauge location improved correlation between the radar rainfall and the gauge data. Peak daily rainfall for the August 5 storm was 93 mm (gauge) and 98 mm (radar), whereas average daily rainfall for the 42-day period was 10 mm and 7.75 mm, respectively. Over the study period, simulated daily infiltration declined from 28 mm to 0.5 mm for the gauge and from 15 mm to 0.14 mm for radar, indicating essentially saturated conditions on the day of the debris flow.

This study evaluated the performance of the early, late and final runs of IMERG version 06 precipitation products at various spatial and temporal scales in China from 2008 to 2017, against observations from 696 rain gauges. The results suggest that the three IMERG products can well reproduce the spatial patterns of precipitation, but exhibit a gradual decrease in the accuracy from the southeast to the northwest of China. Overall, the three runs show better performances in the eastern humid basins than the western arid basins. Compared to the early and late runs, the final run shows an improvement in the performance of precipitation estimation in terms of correlation coefficient, Kling–Gupta Efficiency and root mean square error at both daily and monthly scales. The three runs show similar daily precipitation detection capability over China. The biases of the three runs show a significantly positive (p < 0.01) correlation with elevation, with higher accuracy observed with an increase in elevation. However, the categorical metrics exhibit low levels of dependency on elevation, except for the probability of detection. Over China and major river basins, the three products underestimate the frequency of no/tiny rain events (P < 0.1 mm/day) but overestimate the frequency of light rain events (0.1 ≤ P < 10 mm/day). The three products converge with ground-based observation with regard to the frequency of rainstorm (P ≥ 50 mm/day) in the southern part of China. The revealed uncertainties associated with the IMERG products suggests that sustaining efforts are needed to improve their retrieval algorithms in the future.

Orientadores: Hilton Silveira Pinto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-06T12:34:04Z (GMT). No. of bitstreams: 1 Avila_AnaMariaHeuminskide_D.pdf: 1178810 bytes, checksum: 3b4588a2aea0acf75e80295e33d537b6 (MD5) Previous issue date: 2006 / Resumo: Das variáveis que compõem o balanço hídrico, a precipitação é, certamente, o fator natural determinante da produção agrícola no país. A deficiência hídrica afeta praticamente todos os aspectos relacionados ao desenvolvimento e produtividade das culturas agrícolas. Por outro lado, o excesso de precipitação também pode influenciar negativamente na quantidade e na qualidade dos grãos a serem colhidos. Uma das maiores dificuldades para os tomadores de decisões é o acompanhamento das condições de tempo ocorridas, pois a rede de estações de superfície é deficiente e mal distribuída e nem sempre os dados são disponibilizados. Deve-se considerar ainda que a grande variabilidade espacial e temporal da precipitação impede que o pluviômetro represente adequadamente as chuvas incidentes em uma determinada área. A estimativa de precipitação a partir de imagens obtidas por satélites ou radares, em função da excelente cobertura espacial e temporal, pode apresentar-se como a única forma de obtenção de dados pluviométricos representativos de uma determinada área. O presente trabalho teve como objetivo propor um método de estimativa de precipitação para fins agrícolas, por meio de imagens do satélite meteorológico GOES-12, utilizando como ¿referência terrestre¿ os dados do radar meteorológico do IPMet/UNESP localizado em Bauru e quatro pluviômetros localizados dentro da área de cobertura do radar. Os resultados mostram que precipitações oriundas de nuvens mais frias são mais previsíveis pelos satélites do que provenientes de nuvens mais quentes. Nuvens com temperaturas em torno de 234K são capazes de produzir precipitação, mas nem toda nuvem com essa temperatura pode ser diretamente relacionada com precipitação na superfície. É demonstrado que o limiar de temperatura de brilho de 225K é o mais indicado para estimar precipitação em superfície, reforçando a hipótese de que há uma relação entre as informações obtidas pelo satélite e a precipitação em superfície. Assim como o modelo de MARSHALL E PALMER (1948) apresenta deficiências na relação Z-R, os modelos que utilizam a relação entre refletividade do radar e precipitação obtidos para a região não apresentaram melhor performance. O trabalho desenvolvido indica a possibilidade de acompanhamento de intervalos de estiagens em regiões agrícolas com o uso de imagens satelitarias tornando-se uma ferramenta adequada ao monitoramento agrícola e na estimativa de quebra de safras do país / Abstract: Considering the variables that compose the water balance, precipitation is certainly the most important factor for the agricultural yield in Brazil. The water deficiency affects practically all the aspects related to the development of the cultures. On the other hand, the precipitation excess can interfere as a negative factor in the quality of the final products. One of the highest difficulty for the decision makers in agriculture is the weather monitoring capability since, mainly in Brazil, the meteorological stations network is very poor, badly distributed and the data administrators normally impose restrictions for delivering information. The possibility of estimating precipitation from satellite images in function of the excellent space and time covering cicles can be analysed as an important way for collecting rainfall data for large areas. The present work has the objective of develop a method for estimating rainfall volume for agricultural purposes based on the use of meteorological images collected by the satellite GOES-12 having as terrestrial reference the images of the weather radar of IPMet/UNESP located in the city of Bauru, SP and 4 rain gauges inside the area of radar covering. The results showed that clouds with temperatures around 234K are capable to produce precipitation. As well as the model of MARSHALL and PALMER (1948) showed some deficiencies related to Z-R parameters, the models using the relation between reflectivity of the radar images and precipitation for the region also did not have better performance. The present work shows a possibility of using satellites images for estimating dry spells in large regions of the country that can interfere in the final yield of agriculture / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

Ces dernières années, de nombreux efforts ont été entrepris pour mieux comprendre les phénomènes précipitants parfois à l’origine de crues de cours d’eau et d’inondations ravageuses. Courant 2009, un consortium auvergnat a été mis en place pour notamment surveiller et prévoir ces événements. Les travaux menés dans cette thèse visent d’une part à améliorer les estimations quantitatives des précipitations (QPE) et d’autre part à vérifier les prévisions issues de modèles numériques sur de petites zones d’étude telles qu’une agglomération. L’observation des précipitations peut être réalisée à l’aide soit d’un pluviomètre qui fournit une mesure directe et précise de la quantité de pluie tombée au sol mais ne renseigne pas sur la variabilité spatiale des pluies soit d'un RADAR météorologique qui donne une représentation détaillée de la structure spatiale des précipitations mais dont les estimations sont sujettes à diverses erreurs d’autant plus prononcées en régions montagneuses. Le premier défit de cette thèse a été de trouver la meilleure façon de combiner ces deux informations complémentaires. Deux techniques géostatistiques ont été sélectionnées pour obtenir la meilleur QPE : le krigeage avec dérive externe (KED) et la fusion conditionnée (MERG). Les performances de ces deux méthodes ont été comparées au travers de deux domaines d’étude qui présentent des résolutions spatio-temporelles différentes. La seconde partie de cette thèse est consacrée à la mise en place d’une méthodologie fiable permettant de comparer spatialement les champs de QPE alors reconstruits et les prévisions quantitatives des précipitations (QPF). L’effort fut porté sur le modèle « Weather Research et Forcasting » (WRF). Une étude préliminaire a été réalisée pour tester les capacités du modèle et plus particulièrement des schémas de microphysique à reproduire la pluie. Cette étude assure ainsi l’obtention de prévisions réalistes pour une application sur des cas réels. L’appréciation de la qualité des QPF s’est focalisée sur la quantification spatiale des erreurs de prévision en termes de structure, d’intensité et de localisation des systèmes précipitants (SAL : Wernli et al. 2008, 2009). / In the last decades, many efforts were made to better understand the origins of rain that sometimes lead to rivers runoff or devastating floods. In 2009, a consortium took place in Auvergne in order to observe and predict these events. These works were focused on the improvement of quantitative precipitation estimations (QPE) and the verification of numerical weather models over small areas such as urban environment. Rainfall measurement could be operated either by rain gauges which provides direct and precise rainfall estimations but unfortunately cannot capture the spatial variability or by using weather RADAR which provides a detailed spatial representation of precipitation but estimates are derived indirectly and are subject to a combination of errors which are most pronounced over complex terrain. The main issue of these works was to find the best way to combine both observational systems which are complementary as well. In order to obtain the more truthful fields of QPE, two geostatistical techniques were selected: the kriging with external drift (KED) and the conditional merging (MERG). The performances of these two methods have been experienced on two catchments with different spatial and temporal resolutions. The second part of these works is focused on a reliable method for QPE comparison and quantitative precipitation forecast (QPF). The main effort was focused on the “Weather Research and Forecasting” (WRF) model. A preliminary study was made to check the performances of the microphysics schemes of the model to ensure realistic forecasts for an application on real cases. The spatial verification of the model set up contains three distinct components that consider aspects of the structure, amplitude and location of the precipitation field (SAL : Wernli et al. 2008, 2009).

The dissertation deals with the influence of orography on the spatial distribution of heavy precipitation in the territory of the northeast Moravia and Silesia. The area was chosen because of the specific distribution of daily precipitation for heavy rainfall events in the past and also in May 2010. Cases of heavy rainfall for the period 1961 - 1995 are balanced with morphometric characteristics in the place and in the surrounding the station, defineted in face of direction air flow. For the calculation of the direction air flow are used data from 850 hPa level from reanalysis ERA-40, topographic characteristics are calculated by ArcGIS and they are correlated with the rain gauge data from stations ČHMÚ. The results show us that only the altitude does not have effect on the spatial distribution of precipitation, but it should be think over more topographic parameters. During the north and partially during the west air flow, where the precipitation are mostly from the stratiform clouds, appears a stronger orography influence on the measurement and on the spatial distribution, if we consider the morphometric characteristics behind the station in the direction of air flow. The case of south and east air flow showed us a weaker orography effect, which can be perhaps explained by a higher part of...

This diploma thesis deals with the development of methods for evaluating retention features of green roofs. For the purpose of this thesis, a rainfall simulator was designed and various types of precipitation were examined. The thesis is divided into two main parts: a theoretical part and a practical part. In the theoretical part, the importance of water retention on green roofs is discussed. In addition, a physical theory related to this topic is included and various rainfall simulators used for scientific experiments in the Czech Republic and abroad are described. The practical part deals with the measurement of droplet size and rainfall simulator design. In this part, the process of measuring the flow and the intensity of rainfall by using scales, flow meter and rain gauge is described. For this purpose, a datalogger was developed by the Faculty of Eletrical Engineering in Brno. Finally, the results are sumarized and recommendations on how to conduct the research in the future are provided.