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Authors
Abstract(s)
As mudanças globais estão a afetar todo planeta impactando as atividades
humanas e os serviços de ecossistema. As zonas de montanha mediterrânica
fornecem base para a ocorrência desses tipos de atividades e serviços, todavia são
locais muito afetados pelas alterações globais, extração de recursos naturais e
constate mudança do uso e ocupação do solo. Esses contribuem para o aumento de
riscos hidrológicos, secas e cheias. Para tanto, é necessário estudar fatores que
possam interagir com o risco hidrológico desses territórios, como características
fisiográficas, clima e a resposta hidrológica, a fim de mitigar futuros danos
socioeconômicos. Esses estudos envolvem as características fisiográficas (geometria,
relevo, litologia, pedologia e uso e ocupação do solo), analisar tendências de evolução
temporal de caudais médios e específicos durante as últimas décadas e verificar a
interação das características fisiográficas com a resposta hidrológica. Em vista disso,
esse trabalho abordou três bacias de montanha de dimensão similar (400 – 530 km2)
do nordeste de Portugal: rio Tuela, rio Sabor e rio Maçãs, que compõe um gradiente
climático. Utilizaram-se, então, técnicas de geoprocessamento em software de
Sistemas de Informação Geográfica que caracterizaram a superfície terrestre das
três áreas, métodos de análise de hidrograma e métodos estatístico de estudo de
séries temporais, correlação de Pearson entre as características fisiográficas e os
escoamentos médios e o método do Soil Conservation Service. Diante disso, verificase
que as bacias, apesar de sua proximidade e continuidade, possuem características
fisiográficas similares e distintas, ambas tendo relações diretas com o gradiente
climático presente na área de estudo. As tendências e variabilidades hidrológicas
apontam que as três bacias estudadas pendem para o aumento dos riscos
hidrológicos e que as variabilidades acompanham o gradiente climático, sendo
menor no rio Tuela e maior no Maçãs. Da correlação de Pearson, seu coeficiente
indica relação positiva com os escoamentos médios para as seguintes características:
Leptossolos, altitude média, o declive médio e solos que possuem zonas descobertas
e com pouca vegetação, já relação negativa para: coeficiente de compacidade,
densidade de drenagem, Cambissolos e solos com culturas permanentes. O método
do Soil Conservation Service demonstrou-se eficaz na estimativa do caudal de pico
ao tratar de condições antecedentes de humidade (Antecendent moisture conditions)
do tipo II devido aos valores serem próximos aos observados nas estações
hidrométricas, abordando os períodos de retorno de 2,33, 5 e 10 anos, todavia para
condições tipo III não é recomendado devido os valores serem demasiados
divergentes. Portanto, constata-se que as bacias de montanha exercem muitos papéis
em seu uso e ocupação do solo e que, apesar de próximas, possuem diferenças quanto
a sua caracterização da superfície terrestre. A problemática dos riscos hidrológicos
nessas bacias, de acordo com as respostas hidrológicas, indica tendência para
aumento, mesmo comportando-se de maneiras diferentes. Muitas das características
fisiográficas abordadas possuem relações diretas, comportamentos similares ou
opostos, com os escoamentos médios abordados e com o coeficiente de escoamento,
influenciando assim o regime hidrológico da área de estudo. O método do Soil
Conservation Service pode ser utilizado futuramente para estimativa de caudais de
ponta quando abordado condições do tipo II.
Climate change is affecting the entire planet impacting human activities and ecosystem services. Mediterranean mountain areas provide the basis for these types of activities and services to occur, but they are very affected by climate change, natural resource extraction and the changing of land use. These contribute to increase hydrological, drought and flood risks. Therefore, it is necessary to study factors that may interact with the hydrological risk of these territories, such as physiographic characteristics, climate and hydrological response, in order to mitigate future socioeconomic damage. These studies involve the physiographic characteristics (geometry, relief, lithology, pedology and land use), analyze trends of temporal evolution of medium and specific flows during the last decades and verify the interaction of the physiographic characteristics with the hydrologic response. So, this work approached three mountain basins of similar size (400 - 530 km2) from northeastern Portugal: Tuela River, Sabor River and Maçãs River, which makes up a climate gradient. Were used Geographic Information Systems software with geoprocessing techniques that allowed to characterize the terrestrial surface of the three areas, hydrographic analysis methods and statistical methods of time series study, Pearson correlation between physiographic characteristics and mean flows. and the Soil Conservation Service method. Given this, it is verified that the basins, despite their proximity and continuity, have similar and distinct physiographic characteristics, both having direct relations with the climate gradient present in the study area. Hydrological trends and variability indicate that the three basins studied increase the risk of hydrological risks and that the variability accompanies the climate gradient, being smaller in the Tuela River and larger in the Maçãs River. From the Pearson correlation, its coefficient indicates a positive relationship with the average runoff for the following characteristics: Leptosols, average altitude, the average slope and soils that have uncovered areas and little vegetation, and negative relation for: compactness coefficient, drainage density, Cambisols and soils with permanent crops. The Soil Conservations Service method has been shown to be effective in estimating peak flow when dealing with type II Antecendent moisture conditions because the values are close to those observed at hydrometric stations, for the return periods of 2.33, 5 and 10 years, however for type III conditions it is not recommended because the values are too divergent. Therefore, the mountain basins has a lot of land use kinds and have differences in their characterization of the land surface, even being close to each other. The problem of hydrological risks in these basins, according to the hydrological responses, indicates a tendency to increase, even behaving in different ways. Many of the physiographic characteristics approached have direct relationships, similar or opposite behaviors, with the average flows approached and the flow coefficient, thus influencing the hydrological regime of the study area. The Soil Conservation Service method can be used in future to estimate peak flow rates when addressing type II conditions.
Climate change is affecting the entire planet impacting human activities and ecosystem services. Mediterranean mountain areas provide the basis for these types of activities and services to occur, but they are very affected by climate change, natural resource extraction and the changing of land use. These contribute to increase hydrological, drought and flood risks. Therefore, it is necessary to study factors that may interact with the hydrological risk of these territories, such as physiographic characteristics, climate and hydrological response, in order to mitigate future socioeconomic damage. These studies involve the physiographic characteristics (geometry, relief, lithology, pedology and land use), analyze trends of temporal evolution of medium and specific flows during the last decades and verify the interaction of the physiographic characteristics with the hydrologic response. So, this work approached three mountain basins of similar size (400 - 530 km2) from northeastern Portugal: Tuela River, Sabor River and Maçãs River, which makes up a climate gradient. Were used Geographic Information Systems software with geoprocessing techniques that allowed to characterize the terrestrial surface of the three areas, hydrographic analysis methods and statistical methods of time series study, Pearson correlation between physiographic characteristics and mean flows. and the Soil Conservation Service method. Given this, it is verified that the basins, despite their proximity and continuity, have similar and distinct physiographic characteristics, both having direct relations with the climate gradient present in the study area. Hydrological trends and variability indicate that the three basins studied increase the risk of hydrological risks and that the variability accompanies the climate gradient, being smaller in the Tuela River and larger in the Maçãs River. From the Pearson correlation, its coefficient indicates a positive relationship with the average runoff for the following characteristics: Leptosols, average altitude, the average slope and soils that have uncovered areas and little vegetation, and negative relation for: compactness coefficient, drainage density, Cambisols and soils with permanent crops. The Soil Conservations Service method has been shown to be effective in estimating peak flow when dealing with type II Antecendent moisture conditions because the values are close to those observed at hydrometric stations, for the return periods of 2.33, 5 and 10 years, however for type III conditions it is not recommended because the values are too divergent. Therefore, the mountain basins has a lot of land use kinds and have differences in their characterization of the land surface, even being close to each other. The problem of hydrological risks in these basins, according to the hydrological responses, indicates a tendency to increase, even behaving in different ways. Many of the physiographic characteristics approached have direct relationships, similar or opposite behaviors, with the average flows approached and the flow coefficient, thus influencing the hydrological regime of the study area. The Soil Conservation Service method can be used in future to estimate peak flow rates when addressing type II conditions.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Zonas de montanha NE Portugal Riscos hidrológicos Escoamentos fluviais