Further evidence of changes in the hydrological regime of the River Paraguay: part of a wider phenomenon of climate change?

The time series of 97 annual values, observed or reconstituted, of runoff of the River Amazon at Obidos shows a slight increase of 9% in the mean annual discharges from 1903 to 1999, and of 10% for the floods. All the rupture tests indicate a break in 1970, for the mean annual discharges as well as for the floods. The evolution of the coefficients of variation indicates a reduction in the interannual variability of the mean discharges and floods, from 1927 to 1970. The comparison between the evolution of the mean annual discharges and the average annual rainfall of the basin, from 1945 to 1998, exhibits a good correlation between precipitation and runoff. Finally, the analysis of the evolution of the mean annual discharge and the average annual rainfall, expressed as a percentage of the deviation from the 1945- 1998 averages, demonstrates an increase in the flow in relation to the rainfall, which could be the consequence of the Amazonian deforestation.

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Evolution du débit de l'Amazone à Óbidos de 1903 à 1999

The time series of 97 annual values, observed or reconstituted, of runoff of the River Amazon at Obidos shows a slight increase of 9% in the mean annual discharges from 1903 to 1999, and of 10% for the floods. All the rupture tests indicate a break in 1970, for the mean annual discharges as well as for the floods. The evolution of the coefficients of variation indicates a reduction in the interannual variability of the mean discharges and floods, from 1927 to 1970. The comparison between the evolution of the mean annual discharges and the average annual rainfall of the basin, from 1945 to 1998, exhibits a good correlation between precipitation and runoff. Finally, the analysis of the evolution of the mean annual discharge and the average annual rainfall, expressed as a percentage of the deviation from the 1945–1998 averages, demonstrates an increase in the flow in relation to the rainfall, which could be the consequence of the Amazonian deforestation.

Evolution of the River Amazon’s discharge at Óbidos from 1903 to 1999

The simulation showing transformation of rainfall into streamflow, and routing the generated flows through the streams in a basin, is widely used in many fields of water resources analysis, including understandSimulacao Hidrologica de Grandes Bacias 118 ing the earth surface phase processes of the hydrologic cycle. The early mathematical models developed to simulate this transformation were based on empirical relations between hydrological variables. The newgeneration hydrological models are physically based and distributed, and are adequate to represent small basins. There are few models able to simulate the hydrological processes in large basins, with an adequate physical base. In this paper we present a physically-based large-scale hydrological model, that takes into account the distributed nature of the basin’s characteristics such as land use, vegetation and stream network. The model was applied to two basins, almost 27.000 km2, with very distinct physical characteristics, and with many rainfall and streamflow gauging stations. The model performance, estimated by the fit between measured and calculated daily river discharges at different gauging stations, was very good. Applying the model enabled a preliminary analysis of land use changes in one of the basins, improving the understanding and comparison of the hydrological behavior of both basins. All results show that a large-scale hydrological model is a very useful tool in water resources analysis, even considering the data availability conditions in countries like Brazil. Key-words: simulation; rainfall-streamflow; large basins.

Simulação Hidrológica de Grandes Bacias

Fil: Doyle, Moira Evelina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmosfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmosfera; Argentina

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Attribution of the river flow growth in the Plata Basin

https://www.abrh.org.br/SGCv3/UserFiles/Sumarios/28abb484115f18f906a8ff23c7354a56_50f23b10449257ef21a8637bb7c845c6.pdf

Claudio Kruger

Papers

Análise de Estacionariedade de Séries Hidrológicas na Bacia Incremental de Itaipu

Modelagem Estatística da Precipitação Diária no estado do Paraná

Um estimador de quantis de cheias baseado em assimetria regional