National Institute for Space Research
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Variações na Modelagem do Sequestro Florestal de Carbono por meio de Dados Hiperespectrais na Floresta Nacional do Tapajós, Pará
No full textThe aim of this study is analyze the influence of vegetation indices in spatial forest carbon sequestration, through CO2flux proposed by Rahman et al. (2000) and by changes in its structure by adopting the other vegetation indices (EVI and EVI2) in the Tapajos National Forest, Para, by means of a Hyperion scene. Besides the changes, rates of carbon sequestration were correlated with ICO2 spectral index. We observed more details of photosynthetic activity with these two indices, and the CO2fluxEVI showed intermediate values in the A-B transect, compared to CO2flux, which had the highest values and CO2fluxEVI2 with minors. The highest determination coefficient between the carbon sink and the CO2 content in the atmospheric column of air was obtained with CO2flux (R² = 0.84), but the CO2fluxEVI and CO2fluxEVI2 presented higher R² (0.73 and 0.59) too. The Pearson correlation matrix could be concluded that the NDVI is the index that best correlates with CO2flux and ICO2. However, the other two indexes proposed also have high correlations with the advantage of minimizing saturation, soil background and atmospheric effects.Pages: 9020-902
Estimativa do escoamento superficial distribuído na bacia hidrográfica do rio do Peixe (SP) por meio de geoprocessamento
No full textThe use of remote sensing and geographic information systems (GIS) to facilitate the estimation of runoff from watershed has gained increasing attention in recent years. The curve-number (CN) method from US Department of Agriculture, Natural Resources Conservation Service was used in this study for determine the runoff. Distributed hydrologic models need specific data on land use and its location within the basin. A hydrological model called HEC-GeoHMS (Geospatial Hydrologic Modeling Extension) was used to combine the soil and land use data in to a single shape file and then estimate the CN map. The objective of this paper was to estimate the spatially distributed runoff in the hydrographic basin of Peixe river (Sao Paulo State). For this, remote sensing (TM-Landsat-5 and SRTM - Shuttle Radar Topography Mission) and auxiliary data (soil map and precipitation) was used as input to feed a GIS-based hydrologic model - HEC-GeoHMS. The results showed that the Peixe river basin have few areas with high runoff values (higher than 150 mm month-1), mainly due to high slope and agricultural areas. Also, the results showed no evidences of natural disaster for this basin. The combined use of remote sensing, digital image processing techniques and a distributed hydrologic model was adequate for the study of runoff in the Peixe river basin, allowing the spatial distribution for entire basin, as well as checking areas with greatest natural disaster risk.Pages: 5681-568
Avaliação do produto TRMM 3B42 diário sobre a Região Hidrográfica do Tocantins-Araguaia até o reservatório de Tucuruí-PA
No full textThis study aimed to evaluate the estimates of precipitation obtained through TRMM 3B42 daily v6 algorithm on Tocantins Araguaia River Basin until Tucuruí Hydroelectric Reservoir. To determine this, we selected six regions of interest along the South-North profile of the basin, where TRMM 3B42 daily estimates were compared to the reference precipitation obtained with in situ measurements. The time series used in this study included the period between January 1, 2000 and July 30, 2011. The precipitation estimates of TRMM 3B42 daily algorithm were evaluated by calculating the Pearson product-moment coefficient, the Bias and the Root-Mean-Square Error (RMSE). The results showed that TRMM 3B42 daily product was able to reproduce the precipitation regime of the basin and represent the seasonal variability of rainfall. Despite this, TRMM 3B42 daily product tended to overestimate the precipitation by about 64% (Bias=2.6 mm day-1) over the study area and presented a weak linear correlation with in situ data (r=0.15). The RMSE analysis suggested that the estimates of TRMM 3B42 have low reliability on the study area. However, the differences observed between the estimated precipitation using TRMM 3B42 daily product and the in situ data should not be overrated, since there are uncertainties associated with rain gauge data that were not considered in this evaluation.Pages: 5816-582
Espacialização dos componentes do balanço de energia e de evapotranspiração na região Norte de Minas Gerais, utilizando o modelo SEBAL e imagens orbitais Landsat 5 TM
No full textThe combination of the two processes by which the water vapor is transferred into the atmosphere due to evaporation from the soil and transpiration from vegetation is called evapotranspiration (ET). The determination of ET values is very useful information for planning irrigation, water supply estimation, regulation of water rights and river basins hydrologic studies. Values of ET in the North region of Minas Gerais state were estimated in this research from the multispectral images data of the Landsat 5 TM satellite by means of the model Surface Energy Balance Algorithm for Land- SEBAL, based on the simplified energy balance equation of a surface covered by vegetation, using a few daily surface climatological parameters (wind speed, rainfall, air temperature and relative humidity, solar radiation). The aim of this study was to estimate the regional spatial distribution of the energy balance components and evapotranspiration in the study area, covering the irrigated perimeter of Gorutuba, involving the cities of Nova Porteirinha, Janaúba, Porteirinha, Verdelândia and Pai Pedro. Thematic maps of regional energy balance components, evapotranspiration, and soil cover vegetation conditions were generated from spectral analyzes of the images obtained, associated with the used weather data. The ability of SEBAL to provide the spatial variability of energy balance components, including evapotranspiration, demonstrated its sensitivity to different occupation of the soil surface vegetation, and to high data temporal and spatial resolutions data, indicating that the SEBAL model can be used in scales and operational routine.Pages: 6284-629
Dados LiDAR e análise orientada a objeto no monitoramento de manejo florestal
No full textAlthough selective logging activity has declined significantly in the past decade, it is still an important land use that affects biological diversity and carbon stocks in the Brazilian Amazon. We present initial results of the application of an object-oriented analysis of airborne small-footprint lidar data as a tool for monitoring forest management in the Antimary State Forest in Acre. For a trial area logged within a few months prior to data acquisition, we processed the lidar returns to calculate the relative density of returns between 0 and 1 m height. The resulting product highlights areas with bare-ground or minimal ground vegetation allowing us to visualize the network of roads and skid trails beneath the forest canopy. The product was segmented and classified into two categories: (1) roads and skid trails and (2) and all other. The resulting classification was compared to a reference data set developed by visual interpretation and validated by GPS ground control points. We found that 67.0% of the areas were correctly classified by our technique demonstrating the potential of this tool. In the future we hope to minimize the uncertainty in the classification by inclusion of more parameters into the decision rules for automated segmentation.Pages: 6171-617
Utilización de tecnología satelital para determinar la estimación de superficies agrícolas: Método de segmentos aleatorios
No full textThe Ministry of Agriculture, Livestock and Fisheries (MAGyP) developed and implemented the method known as random segments, for estimating the area planted with different crops in the agricultural areas of the country. This method incorporates the use of Landsat satellite imagery and Google Earth for tasks stratification of homogeneous areas, distribution of points on the surface area, segment design, and specification outlined the use of land plots as true, accurate measurement of selected surfaces and surfaces to expand the sample. Using GPS, to determine the waypoints on the Earth's surface and the satellite image databases and protocols work to organize information, statistical analysis to obtain the results. The results and the low CV achieved have shown that this method is suitable for estimating the area of field crops such as soybeans, wheat, corn, large level areas (covering several departments), in segments with homogeneous land use.Pages: 128-13
Diagnóstico geoambiental da Bacia do Rio São Bento - Goiás com o uso do geoprocessamento
No full textThe São Bento basin is located in the southeast of Goiás state and includes Catalão and Davinópolis cities. Its main drainage it is the São Bento River, who rises in the northern sector of Catalão and flows into the São Marcos River in Davinópolis. This work aimed the diagnosis geoenvironmental of the question area using geoprocessing, with the purpose of proposing a management possible that takes into consideration the multiple use of water. Therefore, we carried out a literature review; morphometric analysis, survey of the physical aspect, which were represented by thematic maps, survey of the data fluviometric and main environmental problems. The results indicated that the study area is predominantly rural, has a poor drainage system, and the physical aspects point out: crystalline and sedimentary rocks, predominance of latosoil and Cambisoils, flat relief in about half of the basin and most rugged in the rest. Flow rates reflect the typology local climate, with a wet season and a dry season, causing the increase and reduction of discharges, respectively. The environmental problems are mainly related to the indiscriminate use of land for agriculture, pasture and reforestation for commercial purposes. Therefore it is important to think in a participatory and integrated management of the basin in question to ensure the quality and availability of water, that does not compromise future generations.Pages: 3818-382
Dinâmica da paisagem no município de Sorocaba - SP, situação reportada nos anos de 1988 e 2011: uma abordagem com o uso de geotecnologias
No full textThe landscape modifications due to anthropogenic factors imply huge impact on the ecosystems, as well as change in global biogeochemistry and climate. One important change that may occur is the replacement of native vegetation by other kinds of land cover, resulting in a fragmentation process of the remaining vegetation. Currently, these changes are investigated through satellite images. Here we evaluated, using remotely sensed images, the dynamic of the land cover change, as well as the dynamic of patches of the natural remnant vegetation (NRV) in the Sorocaba municipality - Brazil for a period of 23 years (1988 and 2011). Our results show that the urban settlement class increased 18.1% during this period. We also observed expansion of NRV category, which shifted from 8772.21 to 12826.89 ha, respectively in 1988 and 2011. Despite of the increasing of the category NRV, in 2011 we quantified 161 less forest fragments than in 1988. However, it was noted that the remaining fragments are larger in area, suggesting a higher interconnectivity degree. Two facts explain such scenario: (a) Sorocaba is not an agricultural municipality, and large areas used for agricultural ends are not observed; and (b) there are some activities aiming reestablish the riparian vegetation along the main water courses, developed by the Municipal Secretary of Environment. These are activities have effectively collaborated on the improvement of the quality of the NRV local.Pages: 7452-745
Improving the predictive performance of a national vis-NIR spectroscopic library by comparing clustering data transformation, and data-mining calibration techniques
No full textEffective agricultural planning requires basic soil information. In recent decades near-infrared diffuse reflectance spectroscopy (NIRS) has been shown to be a viable alternative for rapidly analyzing soil properties. We studied 7171 samples of the soil Brazilian spectral library. The aim was to explore the possibility of enhancing the performance of NIRS data in predicting organic matter and clay content in this library by dividing it into smaller sub-libraries based on their vis-NIR spectra and to compare these results to two nonlinear calibration techniques (BT and SVM) applied to the whole library. The general predictive models for clay performed well (R2 > 0.79), reflecting the influence of the direct spectral responses of this property in the NIRS range. Predictions of OM were reasonably good, especially with clustering, and in view of the very low variation in this parameter. Results showed that the division of the large library into smaller subsets based on the variation in the mean-normalized spectra was the best alternative for using vis-NIR spectra to quantify soil attributes in tropical soils by Partial Least Square regressions. This divided the global data set into clusters that were more uniform in mineralogy, regardless of geographical origin, and improved predictive performance. Another alternative would be to use boosted regression trees for the whole library. It was also possible to identify regions of the vis-NIR spectrum that showed absorption features due to water, iron oxides and clay minerals that their variation might be responsible for the cluster divisions.Pages: 2431-244