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Hydrological impacts of forest conversion to grassland in small catchments in Brazilian Amazonian

Ralph Trancoso, INPA, ralph@inpa.gov.br (Presenting)
Javier Tomasella, CPTEC - INPE, javier@cptec.inpe.br
Arnaldo Carneiro Filho, INPA, carneiro@inpa.gov.br
Maria Terezinha Ferreira Monteiro, INPA, mont@inpa.gov.br
Daniel Andrés Rodriguez, CPTEC - INPE, dandrez@cptec.inpe.br
Rita de Cássia da Silva, CPTEC - INPE, ritacsil@gmail.com.br
Luz Adriana Cuartas, CPTEC - INPE, adriana@cptec.inpe.br
Antonio H. L. do Nascimento, INPA, huxley@inpa.gov.br
Tomé H. L. do Nascimento, INPA, tome@inpa.gov.br

In order to assess the hydrological impact of forest to pasture conversion, a paired micro-catchments experiment (1.2 km2) was set in Central Amazonia. During the study period, total rainfall was very similar in both catchments. In spite of this, significant differences were found in the other water balance components. Evapotranspiration was 1.1 mm.day-1 less in the pasture catchment compared to the forest. Streamflow and water storage were respectively 0.98 mm.day-1 e 0.25 mm.day-1 higher in the pasture catchment. Stormflow yield was 15.28% within forest and 26.41% in the pasture. Runoff coefficients (relation Q/P) were 0.17 and 0.32 for forest and pasture respectively. The analysis of individual events revealed significant differences between forest and pasture in terms of the rainfall/runoff response. The flow duration curves showed more irregular behavior in the pasture catchment. Forest loose a great part of available water by evapotranpiration, it exercises an important ecological role in the balance of hydrological cycle. Observations suggest that forest conversion might have significant impacts on the ability to regularize floods during the wet season and droughts in dry seasons on larger scales.

Science Theme:  HY (Hydrometeorology)

Session:  2A: Hydrological and Meteorological Processes

Presentation Type:  Oral

Abstract ID: 43

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