A biogeochemical characterization of the Madeira river basin has been made to evaluate the local and global effects of possible alterations in the ecosystem caused by recent intensive occupation in Rondonia state. During the period April 1983—January 1986, sampling was made both by land and river along the tributaries and main channel of the Madeira river. The parameters analysed lead to a detailed study of the physicochemical quality of the waters of the basin and their relationship with the local geology, associated with the transport of solid material and the hydrological behavior of the ecosystem.
Penman's method adapted to tropical rainforest conditions was used to evaluate the potential evapotranspiration for the basin. Estimated potential evapotranspiration was 1420 mm/y, 77% due to the energy balance. Real evapotranspiration was 94% of the estimated potential and the main residence time of the rain water in the basin was 2 months. The isotopic behavior of Hydrogen and Oxygen in the river waters of the region was typical of great rivers, the values being more positive during the dry season and more negative during the rainy season. An isotopic gradient of δ 18O 0.038 (‰)/100 km, was established from Porto Velho station to the estuary, which was considered low when compared with the value of 0.063 (‰)/100 km, obtained for the Amazon river.
In general, the waters of the tributaries were poor in dissolved ion species when compared with the main channel of the Madeira river. Seasonal variation in the transport of suspended sediment kept the same pattern, greater transport being observed on rising water than during high water. A transport of 2.85 million tons per day was observed in the Madeira river near the mouth.
KeywordsSuspended Sediment Main Channel Potential Evapotranspiration Tropical Rainforest Local Geology
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- Brinkmann, W. L. F.: Hydrology. In: Lieth, H.; Werger, M. J. (eds.), Tropical Rain Forest Ecosystems, Biogeographical and Ecological Studies. Chapter 5, 89–98 (1989)Google Scholar
- Brasil. Ministério da Agricultura: Aptidao Agricola das Terras de Rondonia. Brasilia 1980.Google Scholar
- Craig, H.: Standard for reporting concentrations of deuterium and oxygen-18 in natural waters. Science 133, 1833–1834 (1961)Google Scholar
- Goncalves, A. R. L.: Determinaçao do tempo de residência da agua da chuva em algumas bacias hidrograficas através de valores de isotopos estaveis. Dissertaçao de Mestrado, ESALQ, 106 p. Universidade de São Paulo, Piracicaba 1979.Google Scholar
- Instituto Brasileiro de Desenvolvimento Florestal: Mapa da alteraçao da cobertura vegetal natural. Departamento de Economia florestal, Brasilia 1985.Google Scholar
- Leopoldo, P. R.; Salati, E.: Rondonia: quandoa floresta vai acabar? Ciencia Hoje 6, 35, 14 (1987)Google Scholar
- Mahar, D. J.: Government Policies and Deforestation in Brasil, Amazon Region. A World Bank Publication in cooperation with World Wildlife Fund and the Conservation Fundation. 56 p. Washington 1988.Google Scholar
- Matsui, E.; Salati, E.; Ferraz, E. S. B.: Medida da variaçao natural da relaçao D/H em amostras de agua. Boletim Cientifico 1, 21 (1971)Google Scholar
- Matsui, E.: A simple method using a disposable syringe to prepare samples for S 18O measurements in water samples. Anal. Chem. Acta 120, 423–425 (1980)Google Scholar
- Mortatti, J.; Salati, E.; Victoria, R. L.; Ribeiro, M. N. G.: Analysis of the isotopic behavior of Hydrogen and Oxygen of water in the main channel of the river Solimmoes/Amazon. SCOPE/UNEP: Transport of Carbon and Minerals in Major World Rivers, part 3, 58, 259–266, 1985.Google Scholar
- Pressenda, L. C. R.; Ferreira, J. R.; Tancredi, A. C. F. N. S.; Martinelli, L. A.; Hirata, R.; Mortatti, J.: Caracterizaçao quimica das aguac de alguno rice do Estado de Rondonia. Acta Limnol. Brasil 1, 179–199 (1986)Google Scholar
- Projeto Radambrasil. Ministério das Minas e Energia: Levantamento de recursos naturais, Folha SC-20, 16, 668 p. Porto Velho 1978.Google Scholar
- Richey, J. E.; Meade, R. H.; Salati, E.; Devol, A. L.; Nordin Jr., C. F.; Santos, U. M.: Water discharge and suspended sediment concentration in the Amazon river: 1982–1984. Water Resour. Res. 22, 5, 756–764 (1986)Google Scholar
- Salati, E.; Lovejoy, T.; Vose, P. B.: Precipitation and water recycling in tropical rain forests with special reference to the Amazon Basin. The Environmentalist 3, 1, 67–71 (1983)Google Scholar
- Villa Nova, N. A.; Salati, E.; Matsui, E.: Estimativa da evapotranspiraçao na bacia amazonica. Acta Amazonica 6, 2, 215–228 (1976)Google Scholar