Biomass Model and Water Balance Application for Watershed Drought Analysis

The hydrological cycle is an important process for monitoring various functions of the landscape. However, changes from land use and natural events, such as drought, have caused several problems in watersheds, such as water scarcity episodes. Thus, the creation of tools for monitoring these events is important in environmental research. Therefore, the objective of this work is delimiting the potential biomass and elaborates the water balance of the Serra Azul stream sub-basin (MG) to analyze the influence of drought on the water storage of the hydrographic basin. The used methodology involved the calculation of the Vegetation Condition Index (VCI), application of the biomass model and evaluation of water balance. Furthermore, a regression analysis was performed between the analyzed data to verify the influence of the variation in biomass and water balance in the worsening of drought in the study region. The results indicated that variations in land use and the natural changes in the hydrological cycle contributed to the worsening of drought proving the effectiveness of biomass model associated to water balance and VCI data for monitoring drought.

AVALIAÇÃO DE ÍNDICES ESPECTRAIS OBTIDOS COM IMAGENS SENTINEL-2 E LANDSAT 8 ANTES E APÓS ROMPIMENTO DA BARRAGEM DA MINA DO FEIJÃO, BRUMADINHO – MG: Evaluation of spectral indexes obtained with SENTINEL 2 and LANDSAT 8 images before and after break of the Feijão Mine Dam, Brumadinho – MG

Remote sensing techniques have been largely used in several environmental analyzes. So they have effectively helped many studies related to soil changes and vegetation health situation. The vegetation index allows straightforward effective analysis of the biomass and the vegetative vigor presented by a region. This paper performed an analysis of the Normalized Difference Vegetation Index (NDVI), by comparing the results obtained with Operational Land Imager (OLI) and Multispectral Instrument (MSI) sensor images. Furthermore, it compared the application of index in images with and without the atmospheric correction techniques. The study area consisted in the region of the Feijão Mine, in Brumadinho – MG where a dam disruption occurred on January 25, 2019.  The study results allowed comparing the images with and without the use atmospheric correction as well as analyzing the region behavior before and after the accident.Métodos e dados de sensoriamento remoto têm sido largamente utilizados em diversas aplicações de análises ambientais. Dentro desse aspecto, a sua utilização tem auxiliado de forma efetiva em análises de mudanças do solo, bem como, nos estudos de vegetação. Os índices de vegetação permitem realizar análises e estudos da biomassa e do vigor vegetativo apresentado por uma região de forma simples e eficaz. Esse artigo realizou uma análise do Índice de Vegetação de Diferença Normalizada (NDVI), comparando os resultados obtidos a partir de imagens dos sensores Operational Land Imager (OLI) e Multispectral Instrument (MSI). Além disso, o estudo realizou uma comparação entre a aplicação do índice em imagens com e sem a utilização de técnicas de correção da atmosfera. A área de estudo é a região da mina do feijão, em Brumadinho – MG, onde ocorreu o rompimento da barragem de rejeitos em 25 de janeiro de 2019.  Os resultados encontrados permitiram realizar uma comparação entre as imagens, com e sem a utilização de técnicas de pré-processamento para correção atmosférica, e analisar o comportamento apresentado pela região antes e depois do acidente

A Influência da Cortina Retentora de Resíduos na Qualidade da Água da Lagoa da Pampulha – Belo Horizonte/MG

A Lagoa da Pampulha é um pequeno reservatório urbano localizado no município de Belo Horizonte, Minas Gerais, que recebe uma carga elevada de nutrientes e lixo oriundos do lançamento de esgotos domésticos e industriais e da poluição difusa, os quais provocam a eutrofização do corpo d’água. Como forma de reduzir os impactos provocados pela poluição na Lagoa foi instalada pelo governo municipal uma cortina retentora de resíduos em sua parte mais estreita. O objetivo deste estudo foi verificar o efeito da cortina retentora de resíduos na dinâmica da qualidade da água da Lagoa da Pampulha a partir de uma análise de parâmetros limnológicos. Foram coletadas amostras de água superficial em uma malha amostral de 29 pontos, em abril de 2018 e foram avaliados os seguintes parâmetros: clorofila-a, turbidez, matéria orgânica colorida dissolvida (CDOM), profundidade (disco de Secchi), pH e temperatura da água. Os pontos de monitoramento foram separados em dois grupos localizados antes e depois da cortina de retenção de resíduos, grupos 1 e 2, respectivamente. A clorofila-a e a turbidez apresentaram a maior variabilidade para os dois grupos e o grupo 2 apresentou valores mais baixos para todos os parâmetros limnológicos analisados, especialmente para clorofila-a, turbidez e CDOM, quando comparado ao grupo 1. Com base em análise estatística, pode-se demonstrar que a cortina de retenção de resíduos é eficaz em reter parte da carga poluidora que chega à Lagoa da Pampulha, diminuindo a concentração de parâmetros limnológicos que podem ser diretamente associados a uma melhor qualidade geral da água

Use of multicriteria analysis to define priority areas for reforestation in the Piranga River Basin, MG, Brazil

The Piranga River Basin is one of the main sub-basins of the Doce River, being one of the most historically explored, which culminated in an emblematic episode, the rupture of the mining tailings dam in Mariana. Those responsible for the damage had to develop solutions to repair the territory, mainly the definition of priority areas for conservation. One factor to consider for this definition was the institution of protected spaces in rural properties, such as the Permanent Preservation Areas (PPAs), consolidated by the new Forest Code (Law No. 12,651 / 2012). For the allocation of intervention areas, the Multicriteria Analysis was adopted, widely used in decision-making processes. The results showed that the southeast area of the Doce River State Park is more likely to receive initiatives to restore native vegetation. The opposite occurs in the more urbanized regions of the basin, which are also coincident with the steepest areas.A Bacia do Rio Piranga é uma das principais sub-bacias do Rio Doce, sendo uma das mais exploradas historicamente, que culminou em um episódio emblemático, o rompimento da barragem de rejeitos de mineração em Mariana. Os responsáveis pelo dano precisaram desenvolver soluções para reparação do território, destacando-se a definição de áreas prioritárias para conservação. Um fator a considerar para essa definição foi à instituição de espaços protegidos em imóveis rurais, como as Áreas de Preservação Permanente (APPs), consolidadas pelo novo Código Florestal (Lei nº 12.651/2012). Para alocação das áreas de intervenção foi adotada a Análise Multicritério, amplamente utilizada em processos de tomadas de decisão. Os resultados mostraram que as áreas a sudeste do Parque Estadual do Rio Doce apresentam maiores propensões a receber iniciativas de restauração de vegetação nativa. Ocorre o contrário nas regiões mais urbanizadas da bacia, que coincidem, também, com as áreas de maior declividade

The use of remote sensing techniques by Modis (MCD45A1) images using to identify and evaluate burned areas in the metropolitan region of Belo Horizonte - MG, Brazil

The study of fire burned areas is very important, since they corroborate with control measures, prevention and monitoring of fires. Forest fires causes numerous impacts, among them, there is biodiversity lost and human health prejudice. So, it is a problem of environmental sphere as well as a social and political sphere. A way of monitoring this is using remote sensing techniques. So the propose of the present article is to use the Modis product (MCD45A1) to identify and evaluated the burned areas in metropolitan region of Belo Horizonte, among the years of 2012 to 2016, which is validated with Landsat-8/OLI sensor data. With the use of Landsat data it is possible to define the size of the burned area with greater precision, but requiring technical operational knowledge and specialized technical staff for both, on the other side, Modis is easier to operate, and have direct application and higher availability. It was observed that the study area has high burned area occurrences, mainly in spring and winter. The results found here could be used for future studies to decrease the forest fires incidence in the region and thus preserve the biodiversity of important biomes present in it.Estudos sobre a ocorrência de queimadas são muito importantes, visto que eles corroboram medidas de controle, prevenção e monitoramento destas. Incêndios florestais causam vários impactos, entre eles perda da biodiversidade e prejuízo à saúde humana, sendo um problema tanto na esfera ambiental quanto social e política. Uma forma de monitoramento desses incêndios é a utilização de técnicas de sensoriamento remoto. Assim, a proposta do presente trabalho foi a utilização de imagens Modis (MCD45A1) para identificação e avaliação de áreas queimadas na região metropolitana de Belo Horizonte, entre os anos de 2012 e 2016, validando-o com dados do sensor Landsat-8/OLI. Com o emprego dos dados Landsat, é possível delimitar com melhor precisão a dimensão da área queimada, mas exigindo-se conhecimento técnico operacional e corpo técnico especializado para tanto. Já o produto decorrente do Modis, é mais acessível e de fácil utilização, sendo de aplicação direta, pois já informa os focos de incêndio. Observou-se grande ocorrência de queimadas na região de estudo, principalmente na primavera e no inverno. Os resultados encontrados aqui poderão ser utilizados em estudos futuros para diminuir a incidência de queimadas na região e assim preservar a biodiversidade de biomas importantes nela presente

Temporal analysis of drought coverage in a watershed area using remote sensing spectral indexes

The development of several time series analysis programs using satellite images has provided many applications based on resources from geostatistics field. Currently, the use of statistical tests applied to vegetation indexes has enabled the analysis of different natural phenomena, such as drought events in watershed areas. The objective of this article is to provide a comparative analysis between NDVI and EVI vegetation index data made available by MOD13Q1 project of MODIS sensor for drought mapping using vegetation condition index (VCI) in the Serra Azul stream sub-basin, MG. The methodology adopted the Cox-Stuart statistical test for seasonality analysis and Pearson's linear correlation to verify the influence of different indexes on delimitation of drought in a watershed. The results indicated the NDVI vegetation index as more efficient than EVI in spatial characterization of studied watershed region, mainly in identification of seasonality. The VCI proved to be highly feasible for monitoring drought in study period between 2013 and 2018, allowing the effective delimitation of drought conditions in the Serra Azul stream sub-basin. In addition, the effectiveness of MODIS sensor data in characterizing drought events that affected the study area was proven

Teaching Methodology for Topography: Didactic Proposal for the Free Station Survey Method

This article presents an innovative proposal for teaching Topography topics, as there are no qualified official publications on the subject of study referring to topographic positioning by the free station method, resulting in a shortage of didactic material on this topic in educational institutions in Brazil. Thus, the research work resulted from the didactics applied in the Topography discipline, of the UFPE's Cartographic Engineering degree program. It was proposed to the students to accomplish some practices of the free station method during the Topography discipline development. Thus, the students carried out a theoretical study on the topic. Subsequently, field work was developed with topographic equipment containing a program for surveying by free station method. Topographic vertices of the cadastral reference network of the “Joaquim Amazonas” campus of UFPE served as reference and adjustment points. A comparative analysis of the results calculated manually with the results obtained by the internal programs of the topographic equipment was carried out, using the official coordinates of the cadastral network as references. A program was developed in MATLAB for fixing the learning, whose results were also compared with the same official reference coordinates. This made it possible to generate a complete quantitative statistical analysis of the results

Técnicas digitais para produção de carta imagem

Many aeronautical charts are made by compilation process over national systematic maps. Unfortunately the basic national cartographic coverage is not yet fully completed and therefore does not provide an effective base for the growing applications of aeronautical charting. A cost-effective alternative solution for minimizing the dependency on systematic maps can be afforded by utilizing image mapping techniques. This paper provides a brief discussion on the main steps required to produce image maps using an entirely digital approach. The guidelines for such digital procedures are under development in Instituto de Cartografia Aeronaulica (ICA) as part of a large image mapping program for aeronautical purposes.Pages: 351-35

Combinação de dados altimétricos extraídos a partir da tecnologia LIDAR com imagens multiespectrais RapidEye

The combination of data from various remote sensors has been increasingly applicability, due to the increasing number of information from remote sensing techniques and the wide variety of resolutions available. The combination of LIDAR altimetry data with information of multispectral satellite image with high spatial resolution has great potential to overcome the limitations of each sensor characteristics, such which little spectral information contained in the data generated by airborne laserscanner and also the low sensitivity of the multispectral images of orbital satellites to capture data on the vertical structure of the targets. The aim of this study is to test the ability of combining altimetry data from LIDAR technology with multispectral images of high spatial resolution satellite RapidEye. The LIDAR point cloud has been processed and interpolated to create a digital image with altimetric information, named Digital Model Height (DMH). To the junction of the information contained in the MDA with the multispectral image RapidEye was used RGB color system, combining two satellite bands with the MDA and then analyzing the color composites derived. The combination of structural data provided by LIDAR technology with the spectral information provided by satellite RapidEye showed great potential for application in analysis of various kinds of environments.Pages: 5540-554

Uniformização radiométrica de imagens multitemporais para composição de mosaicos

Remote sensing images are available in individual scenes that have limited spatial extent. Projects that cover large geographical areas require several individual scenes that need to be joined by means of mosaics. These images that come from neighboring orbits generally have an overlapping zone. The problem is that the junction between two adjacent images in mosaics is generally apparent and so causes interpretation errors and presents non esthetical effects. There are many approaches in literature for solving this problem, but several of those presents some drawbacks in terms of providing an adequate junction. So this paper presents a simple method for equalizing the radiometry of adjacent images in mosaic composition. The method firstly adjusts the gray levels of adjacent images based in statistics of the images overlapping area. In a second step, the method creates an irregular junction line for merging the images based in the minimal local radiometric difference. Finally, the algorithm creates a smoothing effect for merging the images in the vicinity of junction area. The results of tests using LANDSAT images of adjacent orbits, acquired in different times, showed mosaics of very good quality, without the presence of visible joints and with very well balanced radiometry. The resulting mosaics using this approach can be applied in activities requiring extended landscape overviews, as in the case of mapping and cartography applications.Pages: 8246-825