RESUMOSimulações do clima presente foram realizadas no Hadley Center, Reino Unido para o período de 1960 a 1990 com o modelo atmosférico regional HadRM3P aninhado no modelo global HadAM3. Ambos os modelos foram integrados com temperatura da superfície do mar (TSM) observada. Os resultados do HadRM3P, disponibilizados pelo CPTEC/INPE, foram investigados sobre o Estado da Bahia comparandoos com dados diários observados por uma rede de 29 estações meteorológicas do INMET. O modelo foi capaz de simular de forma acurada os principais padrões do ciclo sazonal de precipitação, temperatura e umidade relativa a 2 m em quase todo o Estado da Bahia. Entretanto, a magnitude da precipitação ao longo do litoral foi menor do que a observada, e o modelo não produziu nenhuma precipitação no semi-árido e oeste da Bahia durante os meses de junho-julho-agosto, impondo um cenário climático mais drástico que o observado. O HadRM3P foi também integrado aninhado no modelo acoplado oceano-terra-atmosfera HadCM3, recebendo a TSM prescrita produzida por esse modelo, para simular os cenários climáticos A2 e B2 do IPCC no período de 2070 a 2100. Essas simulações sobre o Estado da Bahia indicaram a redução da precipitação anual e o aumento da temperatura média do ar a 2 m em todo o Estado em relação à simulação do clima presente. O mesmo padrão de modificação da temperatura a 2 m e da precipitação foi produzido para os dois cenários, mas com maiores magnitudes para o A2. A maior redução de precipitação foi observada no litoral -cerca de 70% -e o maior aumento de temperatura foi no noroeste e norte -cerca de 5 o C. Palavras-chave: modelo regional HadRM3P, validação, mudanças climáticas no Estado da Bahia.
ABSTRACT: CLIMATE CHANGE AND WATER RESOURCES IN BAHIA: VALIDATION OF THE HADRM3P PRESENT CLIMATE SIMULATION AND COMPARISON WITH THE A2 AND B2 SCENARIOS FOR 2070-2100Simulations of the present climate were performed in the Hadley Center, UK, for the period with the regional atmospheric model HadRM3P nested in the global model HadAM3 integrated with observed sea surface temperature (SST). The results of this simulation, available at CPTEC/INPE, were investigated over the State of Bahia, Brazil, by comparing them against observed daily data from 29 INMET meteorological stations. The model was able to simulate the main patterns of the seasonal cycle of precipitation, mean 2 m temperature and humidity in the majority of the State of Bahia. However, the magnitude of precipitation along the shore was smaller than observation. Also, the model did not produce any precipitation in the semi-arid and western regions of Bahia during June-July-August. This imposed a more drastic climate scenario than observed. HadRM3P was also integrated nested in the coupled oceanland-atmosphere model HadCM3, with prescribed SST produced by this model, to simulate the IPCC A2 and B2 climate scenarios for the period 2070-2100. These simulations over the State of Bahia showed precipitation decrease and temperature increase with respect to the present climate simulation ov...
Little is known about the hydrological impact of the dams in Brazil, despite the rising energy demand and untapped potential. The Paraguaçu River's discharge has been greatly impacted since 1986 by a large dam built in the lower course of the river. In the 26 years of the history of the dam, the minimum discharges have followed different operational guidelines: 1) there was no established discharge minimum between 1987 and 1996; 2) the discharge minimum was 11 m³s-1 between 1997 and 2004; and 3) hydropower generation began in 2005, when local wet season discharges were either 80 m³s-1 or 160 m³s-1 , and dry-season pulses of 10 m³s-1 , which were adopted as minimum stream flow. The mean annual dam discharge between 1987 and 2012 was 17.4% less than the incoming river flow. While rare events of daily null flow exist in the historic records, hundreds of occurrences of daily null flow have been observed in the outgoing discharge since 1987. Other important hydrologic alterations (IHAs) have included: the one-day minimum, the 3-day minimum and the number of low-discharge pulses. Ecochange analysis indicates an overall discharge loss (ecodeficit) in the system. The period of dam operation has coincided with a noticeable drop in the natural river discharge, when the mean discharge was 32% lower than in the pre-dam period (1947-1986
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