Interceptação da chuva em diferentes formações florestais na região de Santa Maria - RS.

• Autor(a) principal: Sari, Vanessa
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UFSM
• Texto Completo: http://repositorio.ufsm.br/handle/1/7766
• topic: Precipitação incidente; Precipitação interna; Escoamento pelo tronco; Interceptação; Balanço hídrico; Rainfall; Throughfall; Stemflow; Interception; Water balance; CNPQ::ENGENHARIAS::ENGENHARIA CIVIL

ABSTRACT: In regions of natural or planted forests, rainfall interception by vegetation can be an important variable in the hydrological cycle and should not be neglected. This research analyzes the process of interception in different forest types (native and planted) in the region of Santa Maria - RS, at the head of Vacacaí Mirim. The variables Rainfall (R), stemflow (Sf), and throughfall (Tf) were monitored in the period from Dec/09 to Fev/11. Rainfall was monitored in two tipping bucket rain gauges and meteorological station installed in the subbasin on July 14th, 2010. Throughfall was monitored in three plots (areas I, II and III) with dimensions of 12 m x 50 m, 21 m x 12 m and 10 m x 20 m, respectively. The sampling points were installed 40 or 60 cm from the ground and spaced 1 m in straight line. In area I (native forest), 101 stakes were allocated to 40 instruments; where 20 collectors remained in fixed locations and 20 were rotated randomly. In the areas II (native forest) and III (eucalyptus) 60 sampling points were allocated to 20 collectors; at each new collection they were placed one sampling point ahead the former. Stemflow was based on values suggested in literature and by monitoring the flow in three selected trees within each plot, and the interception was calculated as the difference between precipitation and the sum of throughfall and stemflow. The results showed that interception is a key component of the hydrological cycle and, in general, underestimated by the hydrological models.The highest interception value was checked for native forest and the largest stemflow for eucalyptus. The stemflow was higher than the values observed by other authors, revealing that this variable cannot be ruled out in the study of interception. On the other hand, the ranges of variation of throughfall and interception were close to those reported in other studies. The results seem also to suggest that the depth parameter adopted for the calculation of interception using the leaf area index is underestimated and should be 0.4. Statistical analysis of the number of collectors used and necessary to ensure error of 5 mm of throughfall in relation to its average and 90% of confidence, showed that for vegetation such as Eucalyptus, the use of 20 rotating collectors were sufficient in 95.45% of the collections; which may be a reference to works in which there is a pattern of similarity of species. For native forest we observed that when the vegetation has a low density and the similar pattern of canopy, stem diameter and height, the use of 20 rotating collectors would be enough to ensure statistical requirements set out in 71.43% of the samples monitored. When the native vegetation is dense, with standard range of height, stem diameter and crown area, we observed the need for a higher number of collectors equipment of throughfall. The use of 40 collectors (20 fixed and 20 rotational) assured that the statistical requirements stipulated were guaranteed in 60.98% of the samples monitored.