Methodology for the detection of land cover changes in time series of daily satellite images. Application to burned area detection

Revista oficial de la Asociación Española de Teledetección[EN] We have developed a methodology for detection of observable phenomena at pixel level over time series of daily satellite images, based on using a Bayesian classifier. This methodology has been applied successfully to detect burned areas in the North American boreal forests using the LTDR dataset. The LTDR dataset represents the longest time series of global daily satellite images with 0.05° (~5 km) of spatial resolution. The proposed methodology has several stages: 1) pre-processing daily images to obtain composite images of n days; 2) building of space of statistical variables or attributes to consider; 3) designing an algorithm, by selecting and filtering the training cases; 4) obtaining probability maps related to the considered thematic classes; 5) post-processing to improve the results obtained by applying multiple techniques (filters, ranges, spatial coherence, etc.). The generated results are analyzed using accuracy metrics derived from the error matrix (commission and omission errors, percentage of estimation) and using scattering plots against reference data (correlation coefficient and slope of the regression line). The quality of the results obtained improves, in terms of spatial and timing accuracy, to other burned area products that use images of higher spatial resolution (500 m and 1 km), but they are only available after year 2000 as MCD45A1 and BA GEOLAND-2: the total burned area estimation for the study region for the years 2001-2011 was 28.56 millions of ha according to reference data and 12.41, 138.43 and 19.41 millions of ha for the MCD45A1, BA GEOLAND-2 and BA-LTDR burned area products, respectively.[ES] Se ha desarrollado una metodología para la detección de cambios de la cubierta vegetal, a nivel de píxel, en se-ries temporales de imágenes de satélites diarias mediante la utilización de un clasificador bayesiano. Dicha metodología ha sido aplicada satisfactoriamente a la detección de áreas quemadas en los bosques boreales de Norte América en el período 1981 a 2011, utilizando el conjunto de datos Long Term Data Record (LTDR) que constituye la serie temporal más larga de imágenes diarias de satélite a escala global, con una resolución espacial de 0,05° (~5 km). La metodología pro-puesta consta de varias etapas: 1) pre-procesamiento de las imágenes diarias y obtención de imágenes compuestas de ndías; 2) construcción del espacio de las variables o atributos a considerar; 3) diseño del algoritmo, mediante la selección y refinamiento de los casos de entrenamiento; 4) obtención de los mapas de probabilidad relacionados con las clases temáticas a considerar; 5) post-procesamiento para mejorar los resultados obtenidos mediante la aplicación de múltiples técnicas (filtros, rangos, coherencia espacial, etc.). Los resultados finales obtenidos son comparados con los datos de referencia mediante métricas de exactitud derivadas de la matriz de error (errores de comisión y omisión, porcentaje de estimación) y de gráficos de dispersión (coeficiente de correlación y pendientes de la recta de regresión, etc.). La calidad de los resultados obtenidos al aplicar esta metodología a las imágenes LTDR para la detección de área quemada en la región boreal de Norte América mejora en términos de exactitud espacio-temporal a la de los otros dos productos de área quemada globales comparados (MCD45A1, BA GEOLAND-2) a pesar de que utilizan imágenes de mayor resolución espa-cial (y sólo disponibles a partir del año 2000): la estimación de área quemada total sobre la región de estudio en el periodo 2001-2011 fue de 28,56 millones de hectáreas según los datos de referencia y de 12,41, 138,43 y de 19,41 millones de hectáreas para los productos MCD45A1, BA GEOLAND-2 y BA-LTDR, respectivamente.Este trabajo está financiado por el Ministerio de Economía y Competitividad de España a través del proyecto CGL2013-48202-C2-2-R. Un especial agradecimiento a las Agencias y Servicios de procesamiento de datos de satélite de NASA y NOAA, las cuales nos han suministrado la mayor parte de las imágenes empleadas en este trabajo (LANDSAT, MODIS, LAC and LTDR). Finalmente agradecer a los revisores anónimos por sus comentarios constructivos, los cuales fueron especialmente tenidos en consideración.Moreno-Ruiz, J.; Arbelo, M.; García-Lázaro, J.; Riaño-Arribas, D. (2014). Desarrollo de una metodología para la detección de cambios de la cubierta vegetal en series temporales de imágenes de satélite diarias. Aplicación a la detección de áreas quemadas. Revista de Teledetección. (42):11-28. https://doi.org/10.4995/raet.2014.2280SWORD11284

Using Long Time Series of Satellite Remote Sensing Data to Assess the Impact of Climate and Anthropogenic Changes in the Mesopotamian Marshes, Iraq

In the recent past, the Mesopotamia region has been rich in all forms of biological diversity, characterized by a fertile living environment and natural habitats full of rare birds, wild animals, aquatic animals, and diverse plants. Its natural abundance and geographical location have allowed it to be break or transit point for millions of migratory birds from Russia to South Africa. It is a breeding ground for many species of Persian Gulf fish. Despite all this historical, environmental and economic richness, they have been neglected as a result of the combination of a number of human and climatic factors, which in 16 years (1988-2003) has modified them to a land where vegetation, water, and biodiversity have been clearly reduced. This is a great environmental loss, not only for West Asia but for the whole world. This dissertation explores the changes in the vegetation coverage and water bodies in the Mesopotamian marshes, Iraq over more than three decades (36 years) using different sources of satellite remote sensing datasets. Firstly, we utilized Normalized Difference Vegetation Index (NDVI) from the Land Long Term Data Record (LTDR) Version 5 which has a 0.05o x 0.05o in spatial resolution and daily temporal repeat to monitor the fluctuations of vegetation together with hydrological variables such precipitation, surface temperature, and evapotranspiration. In this research, we studied the impact of climate change and anthropogenic activities on vegetation and water coverage changes. Secondly, we compared Normalized Difference Vegetation Index from various satellite sensors - Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High-Resolution Radiometer (AVHRR), and Landsat over the Mesopotamian marshlands for 17 years. We selected this time series (2002-2018) to monitor the changes in vegetation area. The time series (2002-2018) is considered as a period of rehabilitation for the Mesopotamian marshes. Thirdly, as a result of human factors and local and regional climate changes, the marshes and Iraq are in general vulnerable to face a large number of dust storms annually. According to local sources (Iraq news) and National Aeronautics and Space Administration, the time period from June 29 to July 8, 2009, is considered the longest dust storm period in Iraq during last decade. In this research, we utilized the Moderate Resolution Imagining Spectroradiometer, surface reflectance daily data to calculate the Normalized Difference Dust Index. Additionally, brightness temperature data from Aqua thermal band 31 were used to separate sand on the ground from atmospheric dust. The main reasons for the degradation of the Mesopotamian marshes were due to anthropogenic activities. In the comparison research, we found that the NDVI derived from MODIS, AVHRR and Landsat sensors are correlated with high precision. This paper investigates the utility of combining low spatial resolution with frequent temporal repeat and long-term coverage and a high spatial resolution with infrequent temporal repeat and similar long-term coverage. This study also proves that we can use the low-resolution Advance Very High- resolution Radiometer data for studies on land cover change