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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An?lise da precipita??o no semi-?rido potiguar

Garcia, Joema Ferreira da Costa 30 June 2011 (has links)
Made available in DSpace on 2014-12-17T15:03:27Z (GMT). No. of bitstreams: 1 JoemaFCG_DISSERT.pdf: 801033 bytes, checksum: d6b34753910a92ddda7617d160f165bb (MD5) Previous issue date: 2011-06-30 / The semiarid rainfall regime is northeastern Brazil is highly variable. Climate processes associated with rainfall are complex and their effects may represent extreme situations of drought or floods, which can have adverse effects on society and the environment. The regional economy has a significant agricultural component, which is strongly influenced by weather conditions. Maximum precipitation analysis is traditionally performed using the intensity-duration-frequency (IDF) probabilistic approach. Results from such analysis are typically used in engineering projects involving hydraulic structures such as drainage network systems and road structures. On the other hand, precipitation data analysis may require the adoption of some kind of event identification criteria. The minimum inter-event duration (IMEE) is one of the most used criteria. This study aims to analyze the effect of the IMEE on the obtained rain event properties. For this purpose, a nine-year precipitation time series (2002- 2011) was used. This data was obtained from an automatic raingauge station, installed in an environmentally protected area, Ecological Serid? Station. The results showed that adopted IMEE values has an important effect on the number of events, duration, event height, mean rainfall rate and mean inter-event duration. Furthermore, a higher occurrence of extreme events was observed for small IMEE values. Most events showed average rainfall intensity higher than 2 mm.h-1 regardless of IMEE. The storm coefficient of advance was, in most cases, within the first quartile of the event, regardless of the IMEE value. Time series analysis using partial time series made it possible to adjust the IDF equations to local characteristics / O regime pluviom?trico no semi-?rido Nordestino ? altamente vari?vel. Os processos clim?ticos associados ?s precipita??es s?o complexos e seus efeitos podem representar situa??es limites de seca ou enchentes, os quais podem ter efeitos negativos para a sociedade e meio ambiente. A economia da regi?o, com forte componente agr?rio, ? fortemente impactada pelas condi??es clim?ticas. A an?lise de chuvas intensas ? feita tradicionalmente utilizando as equa??es tipo intensidadedura??o- freq??ncia (IDF). Os resultados obtidos nesses estudos s?o usados em projetos de engenharia envolvendo obras hidr?ulicas, tais como rede de drenagem e obras vi?rias. Por outro lado, a an?lise dos dados de precipita??o pode exigir a ado??o de algum tipo de crit?rio de identifica??o de eventos. Um dos crit?rios mais usados ? o intervalo m?nimo entre eventos (IMEE). Este estudo tem o objetivo de analisar o efeito do IMEE nas caracter?sticas dos eventos de precipita??o. Para isso, foi usada uma serie hist?rica de precipita??o com 9 anos de registros (2002-2011). Os dados foram registrados numa esta??o pluviogr?fica autom?tica instalada na Esta??o Ecol?gica do Serid?. Os resultados demonstraram que o valor do IMEE adotado tem um efeito importante no numero de eventos, dura??o, altura precipitada, intensidade m?dia e no intervalo m?dio entre eventos. Al?m disso, verificou-se uma maior ocorr?ncia de eventos extremos para pequenos valores de IMEE. A maioria dos eventos apresentou intensidade m?dia acima de 2 mm/h, independente do IMEE adotado. O coeficiente de avan?o da tormenta situou-se, na maioria dos casos, no primeiro quartil do evento, independente do valor do IMEE. A an?lise probabil?stica dos dados observados utilizando s?ries parciais possibilitou o ajuste de equa??es IDF caracter?sticas do local

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