Marcos Antônio Timbó Elmiro

Aplicação do modelo SWAT na avaliação do consumo de água em áreas de florestas plantadas na bacia do rio pará, Alto São Francisco, em Minas Gerais

Forests are very important for the balance of the hydrological cycle. There is, however, a discussion on whether plantations increase exaggeratedly water consumption in watersheds, especially if such plantations replace original smaller-size vegetation such as in the cerrado. This study aimed to investigate the influence of reforestation in maintenance and balancing the hydrological cycle in the basin of the Para River, Upper San Francisco, Minas Gerais, using the hydrological model SWAT. The results show the efficiency of environmental modeling as a method to detect impacts on water balance due to changes in vegetation cover. The diagnosis revealed a reduction of 4.26% in the scenario of bushland use, 9.68% on average reforestation scenario, and 11.59% in the intensive reforestation. The retention curve suggests the existence of large natural storage indicating a high degree of resilience of the hydrological behavior. Besides plant cover, the results also indicate a close influence of physical and climatic variables in governing water production in the basin. The results generated by the SWAT model were satisfactory, producing reliable and meaningful estimates for the analyses. It is noteworthy that the model adequately considered the variables in its structure, showing its effectiveness in consistently representing the behavior of the basin according to the spatial and temporal distribution. Thus, the results indicate that changes in the short and medium term in the use and land cover in a watershed can cause either higher or lower impacts depending on the physical and climatic variables of water regime.

Digital Height Modeling (DHM) of Tropical Forests using Multi-frequency InSAR Methodology

The objective of this study was to verify how digital elevation models (DEM) built by P-band repeat pass synthetic aperture radar (SAR) interferometry (InSAR) and X band InSAR can be used for estimating a digital height model (DHM) of forested environments and assess its quality. P band signal penetrates towards the forest floor which potentially generates a ground level DEM. X band radar reflects on the top of the vegetation cover, so X band InSAR produces a digital surface model (DSM). The DSM-DEM difference is a map of the vegetation cover height, the DHM. The estimated DHM can be used for forest volume estimation over large areas and used for improving SAR image interpretation either in P or X band. In September 2000, the National Institute for Space Research of Brazil (INPE) and the Brazilian Army Cartographic Service Division (DSG) conducted a mission over the Tapajo acutes National Forest, Para acute State, Brazil when X and P band InSAR data was obtained. Extensive ground data collection, forest inventory, land cover identification and differential GPS altitude measurements was done over the area to permit proper results assessment. It was concluded that the estimated DHM has a good relationship with the vegetation cover height, (r2~0.96) estimated from forest parameters measured on the ground survey.