As mudancas climaticas deverao ter graves consequencias sociais e economicas. No entanto, poucos ... more As mudancas climaticas deverao ter graves consequencias sociais e economicas. No entanto, poucos estudos tem avaliado o impacto das incertezas da mudanca climatica na disponibilidade hidrica de complexos sistemas de redes de reservatorios. A incerteza e agravada quando os reservatorios nao possuem monitoramento das vazoes afluentes. Nesses casos, a regionalizacao dos parâmetros de modelos hidrologicos representa uma estrategia comum para se estimar as vazoes afluentes. Propagar as incertezas associadas aos parâmetros para as bacias nao monitoradas apresenta-se, no entanto, como um desafio metodologico ainda em discussao. Neste estudo, propoe-se uma estrategia de regionalizacao, baseada no metodo de classificacao K-Nearest-Neighbor (K-N-N), que incorpora explicitamente as incertezas associadas aos parâmetros do modelo hidrologico. Tais incertezas, bem como aquelas provenientes da mudanca climatica, foram propagadas para as bacias nao monitoradas dos reservatorios no estado do Ceara, ...
Inter-basin water transfers are the root of many conflicts, and water scarcity accentuates them. ... more Inter-basin water transfers are the root of many conflicts, and water scarcity accentuates them. Those conflicts involve the priority of water use between regions. The Jaguaribe Metropolitan system, located in the Brazilian semiarid region, presents conflicts amongst different water users: irrigated perimeters, industry, and households. This paper analyzed the Jaguaribe Metropolitan water transfer during the 2012–2018 drought by considering environmental and societal aspects. Changes in consumption and users’ drought perception were assessed. The results showed that the drought was longer and more severe in the region that provided water (i.e., Jaguaribe) than in the region that received it (i.e., FMR). Jaguaribe irrigators were aware of the beginning of the drought, but it did not result in immediate consumption control. On the other hand, drought perception was delayed in the FMR. The results of this study suggested that the water allocation decision-making process should include ...
Droughts affect basic human activities, and food and industry production. An adequate drought for... more Droughts affect basic human activities, and food and industry production. An adequate drought forecasting is crucial to guarantee the survival of population and promote societal development. The Standard Precipitation Index (SPI) is recommended by the World Meteorological Organization (WMO) to monitor meteorological drought. Using drought classification based on SPI to build Markov chains is a common tool for drought forecasting. However, Markov chains building process produce uncertainties inherent to the transition probabilities estimation. These uncertainties are often ignored by practitioners. In this study the statistical uncertainties of using Markov chains for drought annual forecasting are assessed. As a case study, the dry region of the State of Ceará (Northeastern Brazil) is analyzed, considering the precipitation records from 1911 to 2019. In addition to 100-year database for Markov chain modeling and 8-year data (2012-2019) for forecasting validation, four fictional database extensions were considered in order to assess the effect of database size in the uncertainty. A likelihood ratio is used to assess model performance. The uncertainties assessment showed that an apparent performant Markov chain model for drought class forecasting may not be more informative than the historic proportion of drought class. Considering these uncertainties is crucial for an adequate forecasting with Markov chains.
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Papers by Ályson Estácio