Land Cover Change Monitoring Using Landsat MSS/TM Satellite Image Data over West Africa between 1975 and 1990

Abstract: Monitoring land cover changes from the 1970s in West Africa is important for assessing the dynamics between land cover types and understanding the anthropogenic impact during this period. Given the lack of historical land cover maps over such a large area, Landsat data is a reliable and consistent source of information on land cover dynamics from the 1970s. This study examines land cover changes occurring between 1975 and 1990 in West Africa using a systematic sample of satellite imagery. The primary data sources for the land cover classification were Landsat Multispectral Scanner (MSS) for 1975 and Landsat Thematic Mapper (TM) for the 1990 period. Dedicated selection of the appropriate image data for land cover change monitoring was performed for the year 1975. Based on this selected dataset, the land cover analysis is based on a systematic sample of 220 suitable Landsat image extracts (out of 246) of 20 km × 20 km at each one degree latitude/longitude intersection. Object-based classification, originally dedicated for Landsat TM land cover change monitoring and adapted for MSS, was used to produce land cover change information for four different land cover classes: dense tree cover, tree cover mosaic, other wooded land and other vegetation cover. Our results reveal that in 1975 about 6% of West Africa was covered by dense tree cover complemented with 12% of tree cover mosaic. Almost half of the area was covered by other wooded land and the remaining 32% was represented by other vegetation cover. Over the 1975–1990 period, the net annual change rate of dense tree cover was estimated at −0.95%, at −0.37% for the other wooded land and very low for tree cover mosaic (−0.05%). On the other side, other vegetation cover increased annually by 0.70%, most probably due to the expansion of agricultural areas. This study demonstrates the potential of Landsat MSS and TM data for large scale land cover change assessment in West Africa and highlights the importance of consistent and systematic data processing methods with targeted image acquisition procedures for long-term monitoring.JRC.H.5-Land Resources Managemen

Evolución de la cubierta forestal de la cuenca del Duero: análisis multitemporal mediante teledetección

Se presenta un estudio de la evolución de la cubierta forestal en cuatro sub-cuencas de la cuenca del Duero mediante el uso de imágenes Landsat desde mediados de los años 70 hasta la actualidad. El estudio se basa en el análisis multitemporal en las cuencas del Esla, el Carrión, el Tormes y el Alto Duero, todas ellas representativas de las diferentes vertientes hidrográficas. A diferencia de lo que se observa en la mayoría de los estudios realizados sobre la evolución de la superficie de bosque, que utilizan como punto de partida la foto aérea de 1956 y que, como máximo, aportan mapas de la distribución de los usos/coberturas de suelo en dos o tres fechas durante la década de los 90 o en la actualidad, en este trabajo se han utilizado todas las imágenes disponibles (entre 10 y 13 por cuenca). De esta forma se consiguió una serie homogénea en el tiempo y con un número de mapas suficiente para realizar un análisis de tendencias y determinar de manera rigurosa la existencia o no de una evolución clara. En una fase preliminar se empleó cartografía base del Mapa de Cultivos y Aprovechamientos y del Mapa Forestal de España, mapas de los Inventarios Forestales Nacionales y ortofotos aéreas como datos auxiliares para definir las clases de cubierta, seleccionar las zonas de entrenamiento y validar los resultados. Para la caracterización espectral de las distintas clases se utilizaron para cada escena y fecha el NDVI (Normalized Difference Vegetation Index) y las reflectividades de superficie de las bandas visible, infrarrojo cercano e infrarrojo de onda corta, tras los procesos de calibración y corrección geométrica, radiométrica y atmosférica. El método elegido para la discriminación de cubiertas boscosas ha sido el de clasificación supervisada por máxima probabilidad y el posterior refinado de resultados mediante filtrado y criterios condicionales. Finalmente, los resultados se evaluaron mediante matrices de confusión generadas a partir del Mapa Forestal de España (2002-2004), y también se compararon las superficies obtenidas por el proceso de clasificación con las de la cartografía base de los IFN y del programa CORINE. Los resultados muestran que, a diferencia de lo que ha ocurrido en las principales zonas forestales de España, en la cuenca del Duero la superficie de bosque no ha aumentado en los últimos 40 años. Dicha cubierta muestra una tendencia claramente negativa en tres de las cuencas estudiadas.Este trabajo ha sido posible gracias a la financiación del Proyecto SA212A11-2 de la Junta de Castilla y León. Los autores también agradecen al United States Geological Survey (USGS) y a la Agencia Europea del Espacio (ESA) las imágenes Landsat

FOREST AREA CHANGES THROUGHOUT THE YEARS IN BJELOVARSKO-BILOGORSKA COUNTY

The results of forest cover reduction were obtained using raster data and administrative borders for the Republic of Croatia. Examples are taken from other countries to compare the results and show the reduction of cover, both forest and agricultural. The first part of this paper describes the situation in the Republic of Croatia, where Ministry of Environmental Protection provided analysis. The condition of land cover in the Republic of Croatia is presented. The second part of this paper is a description of the task development process in the software package "QGIS". From adding CLC raster data to, the actions performed in the program that were performed until the results arrived. Finally, the interpretation of the obtained data and the conclusion follow

A Hybrid Image Classification Approach to Monitoring LULC Changes in the Mining District of Prestea-Huni Valley, Ghana

Mining and other anthropogenic activities are increasingly destroying forest cover in tropical forest areas of Africa, threating to deplete the entire forest reserves. These depletions not only affect the ecosystems but also have dire implications on global ecological balance and climate. Using Landsat 7 ETM+ satellite images, the study used a combined unsupervised and supervised classification methods to determine the rate of change of the various land use and land cover classes in the mining district of Prestea Huni Valley. The method produced very high accuracies with the least overall accuracy being 95.4272% with a Kappa coefficient of 0.9339. A change detection analysis revealed very significant loss of forest cover as a result of direct mining activities to be 96.78 square kilometres between 2002 and 2015. The results also suggested an overall forest cover loss rate of about 71.63 square kilometres per annum for the periods between 2002 and 2015 which poses a threat to the 493.55 square kilometres of forest cover left in the study area study, if proper monitoring and rehabilitation programmes are not put in place. Keywords: LULC, Degradation, Hybrid Classification, Surface Mining, Forest Cover, Environment, Landsat ETM

CRITICAL PERSPECTIVES ON AGRICULTURAL LAND-USE CHANGE: EVIDENCE FROM SUB-SAHARAN AFRICA

Agricultural Land-Use Change (ALUC) in Sub-Saharan Africa has emerged as a dynamic issue in theenvironment-development discourse. Unpacking what perspectives exist in scholarly publications is relevantsince scholarly ideas often shape policy directions. This paper offers critical reflections on the three broadcategories of perspectives on ALUC that have implications on agricultural productivity and environmentalwellbeing: Agricultural land expansion, agricultural land reduction, and agricultural intensification. Differentfactors were found to have driven these changes in the region. They include; population growth, economicopportunities, poverty, land tenure, environmental factors, government policies, urban development, and landconflicts. The paper highlights how agriculture in the region has contributed to and has been affected by changesin the landscape over the years. It shows that the region has experienced all the three manifestations ofagricultural land-use change, and has the presence of observable variation in the pattern of change across itsgeographical landscape

The dynamics of land use-land cover changes for the years 1984, 1992, 2001 and 2014 in Mutasa district, Zimbabwe

Tropical woodlands in southern Africa are a primary focus of conservation efforts because they are currently under threat from rapid clearing for agriculture and human settlements. A study was carried out in Mutasa district (18°35′0″S and 32°45′0″E) in northern Eastern Zimbabwe using data that spanned the period 1984 to 2014 in order to quantify the spatial and following the conversion to agricultural lands. The land cover changes analysis for the district showed a marked decline in land areas under woodland and considerable increase in area devoted to cultivation. Temporal land-use and land cover changes in Mutasa district on the woodland and plantation forests cover.The annual rate of net cover change from natural woodland to cropland in the district was 0.8% and this was generally higher than the annual rate of net cover changes in tropical Africa which averages 0.36%. The period from 1992 to witnessed the highest daily conversion rate of commercial farm land under woodland (miombo) and forest plantations to cropland of about 3 ha per day and this also coincided with the Fast Track Land Reform Programme which started in 2000

リモートセンシング ト GIS ニ ヨル トチ リヨウ トチ ヒフク ノ ヘンカ ノ スイテイ ニ ツイテ ：ガボン コク デ ラ モンダ ホゴ リン ノ バアイ

Foret Classee de la Mondah（FCM）ラ・モンダ保護林の土地利用・土地被覆（LULC）の変化について、定性的及び定量的に説明し、主な変動因子を求めた。このため、2000年4月7日にETM+、及び、2014年4月6日にOLIによる2時期の観測データについて、最尤法により分類後にLULCの変化を求めた。この結果、周辺地域の人口増加にともない宅地面積が20倍に急増し、不可逆的な人為的変化が見いだされた。これに加え、森林地域の面積が9.77%減少した。現地調査におけるGPSにより特定した位置情報、Google Earthによる高解像度データをサンプル領域の抽出あるいは分類結果の検証に利用した。LULCの持続的な管理を可能とするための保全政策を検討する段階で、政策立案者に対して、参照データとなる関連情報を見出すことができた。The Land Use / Land Cover (LUCL) changes in Foret Classee de la Mondah (FCM) in Gabon was studied to account for changes occurred in the past as a categorical and numerical changes and to explain their main driving causes. For this purpose, the LULC changes were analyzed using post-classification comparison technique, following to the maximum likelihood supervised classification, between two multi-temporal Landsat images of ETM+ and OLI, which were acquired on April 7th 2000 and April 6th 2014, respectively. Results highlighted irreversible human-induced changes, where the rapid growth of built-up areas exhibited 20 times from its initial area, because of the anthropogenic pressure of surrounding population. In addition, major changes occurred mainly in forested area with the loss of 9.77% of its initial area. During the classification process, the use of collateral data, such as GPS coordinates and high resolution images retrieved from ground survey and Google Earth, were extremely relevant to enhancement of sample selection of ROSs and for the validation of classification map as well. However, this study provided relevant findings which could be used as a reference for decision makers while developing conservation policies in order to generate sustainable LULC management practices

Dynamique d’Utilisation des Terres (1991-2023) des Plantations d’Anacarde dans la Zone Soudano-Guinéenne du Centre Bénin

La filière anacarde est en pleine expansion au Bénin où elle est entrain de modifier le paysage de la zone. L’objectif de cette étude était d’analyser la dynamique spatio-temporelle des plantations d’anacardier dans la zone soudano-guinéenne du centre du Bénin de 1991 à 2023 tout en essayant de comprendre les différents facteurs qui peuvent engendrer ces changements. Pour atteindre ces objectifs des données satellitaires multidates Landsat (1991, 2003, 2013) et sentinel 2 (2023) ont été mises à contributions pour évaluer l’occupation et le taux d’évolution des plantations d’anacardier dans la zone d’étude. Ainsi, pour chaque image, une classification dirigée avec l’algorithme « maximum de vraisemblance » a été appliquée suivie d’une analyse en post-classification pour la discrimination des unités. La précision globale de classifications obtenues est supérieure à 80 %. Les résultats révèlent que les plantations ont connu une dynamique évolutive dans la zone d’étude. De 1991 à 2023, la superficie des plantations est passée de 304,82 Km² soit 13,38% de la superficie de la zone d’étude à 342,95 Km² soit 15,055%. Ces transformations progressives ont été observées au détriment des strates autres formations végétales, des zones de culture et des plans d’eau dans la zone d’étude. Cette étude révèle ainsi un processus de régression des unités d’occupation du sol des terres cultivées et autres formations végétales en faveur des plantations d’anacardier. Leur dynamique progressive a aussi des fondements socioéconomiques pérennisables grâce à la gestion sylvicole du système anacardier-cultures annuelles et un accompagnement des projets/programmes et des structures étatiques qui interviennent dans le domaine.  The cashew nut sector is expanding rapidly in Benin and is changing the landscape of the area. The aim of this study was to analyse the spatio-temporal dynamics of cashew plantations in the Sudano-Guinean zone of central Benin from 1991 to 2023, while attempting to understand the various factors that may be causing these changes. To achieve these objectives, multi-date Landsat (1991, 2003, 2013) and Sentinel 2 (2023) satellite data were used to assess the occupancy and rate of change of cashew plantations in the study area. For each image, a directed classification using the 'maximum likelihood' algorithm was applied, followed by a post-classification analysis to discriminate between units. The overall accuracy of the classifications obtained was greater than 80%. The results show that plantations have undergone a dynamic evolution in the study area. From 1991 to 2023, the surface area of plantations increased from 304.82 km², or 13.38% of the surface area of the study area, to 342.95 km², or 15.055%. These gradual changes were observed to the detriment of other plant formations, cultivated areas and water bodies in the study area. This study thus reveals a process of regression of cultivated land and other vegetation cover units in favour of cashew plantations. Their progressive dynamics also have socio-economic foundations that can be sustained through silvicultural management of the cashew-annual crop system and support from projects/programmes and government structures involved in the field.&nbsp

Dynamique d’Utilisation des Terres (1991-2023) des Plantations d’Anacarde dans la Zone Soudano-Guinéenne du Centre Bénin

La filière anacarde est en pleine expansion au Bénin où elle est entrain de modifier le paysage de la zone. L’objectif de cette étude était d’analyser la dynamique spatio-temporelle des plantations d’anacardier dans la zone soudano-guinéenne du centre du Bénin de 1991 à 2023 tout en essayant de comprendre les différents facteurs qui peuvent engendrer ces changements. Pour atteindre ces objectifs des données satellitaires multidates Landsat (1991, 2003, 2013) et sentinel 2 (2023) ont été mises à contributions pour évaluer l’occupation et le taux d’évolution des plantations d’anacardier dans la zone d’étude. Ainsi, pour chaque image, une classification dirigée avec l’algorithme « maximum de vraisemblance » a été appliquée suivie d’une analyse en post-classification pour la discrimination des unités. La précision globale de classifications obtenues est supérieure à 80 %. Les résultats révèlent que les plantations ont connu une dynamique évolutive dans la zone d’étude. De 1991 à 2023, la superficie des plantations est passée de 304,82 Km² soit 13,38% de la superficie de la zone d’étude à 342,95 Km² soit 15,055%. Ces transformations progressives ont été observées au détriment des strates autres formations végétales, des zones de culture et des plans d’eau dans la zone d’étude. Cette étude révèle ainsi un processus de régression des unités d’occupation du sol des terres cultivées et autres formations végétales en faveur des plantations d’anacardier. Leur dynamique progressive a aussi des fondements socioéconomiques pérennisables grâce à la gestion sylvicole du système anacardier-cultures annuelles et un accompagnement des projets/programmes et des structures étatiques qui interviennent dans le domaine.  The cashew nut sector is expanding rapidly in Benin and is changing the landscape of the area. The aim of this study was to analyse the spatio-temporal dynamics of cashew plantations in the Sudano-Guinean zone of central Benin from 1991 to 2023, while attempting to understand the various factors that may be causing these changes. To achieve these objectives, multi-date Landsat (1991, 2003, 2013) and Sentinel 2 (2023) satellite data were used to assess the occupancy and rate of change of cashew plantations in the study area. For each image, a directed classification using the 'maximum likelihood' algorithm was applied, followed by a post-classification analysis to discriminate between units. The overall accuracy of the classifications obtained was greater than 80%. The results show that plantations have undergone a dynamic evolution in the study area. From 1991 to 2023, the surface area of plantations increased from 304.82 km², or 13.38% of the surface area of the study area, to 342.95 km², or 15.055%. These gradual changes were observed to the detriment of other plant formations, cultivated areas and water bodies in the study area. This study thus reveals a process of regression of cultivated land and other vegetation cover units in favour of cashew plantations. Their progressive dynamics also have socio-economic foundations that can be sustained through silvicultural management of the cashew-annual crop system and support from projects/programmes and government structures involved in the field.&nbsp

Dynamique d’Utilisation des Terres (1991-2023) des Plantations d’Anacarde dans la Zone Soudano-Guinéenne du Centre Bénin

La filière anacarde est en pleine expansion au Bénin où elle est entrain de modifier le paysage de la zone. L’objectif de cette étude était d’analyser la dynamique spatio-temporelle des plantations d’anacardier dans la zone soudano-guinéenne du centre du Bénin de 1991 à 2023 tout en essayant de comprendre les différents facteurs qui peuvent engendrer ces changements. Pour atteindre ces objectifs des données satellitaires multidates Landsat (1991, 2003, 2013) et sentinel 2 (2023) ont été mises à contributions pour évaluer l’occupation et le taux d’évolution des plantations d’anacardier dans la zone d’étude. Ainsi, pour chaque image, une classification dirigée avec l’algorithme « maximum de vraisemblance » a été appliquée suivie d’une analyse en post-classification pour la discrimination des unités. La précision globale de classifications obtenues est supérieure à 80 %. Les résultats révèlent que les plantations ont connu une dynamique évolutive dans la zone d’étude. De 1991 à 2023, la superficie des plantations est passée de 304,82 Km² soit 13,38% de la superficie de la zone d’étude à 342,95 Km² soit 15,055%. Ces transformations progressives ont été observées au détriment des autres formations végétales, des zones de culture et des plans d’eau. Cette étude révèle ainsi un processus de régression des unités d’occupation du sol des terres cultivées et autres formations végétales en faveur des plantations d’anacardiers. Leur dynamique progressive a aussi des fondements socioéconomiques pérennisables grâce à la gestion sylvicole du système anacardier-cultures annuelles et un accompagnement des projets/programmes et des structures étatiques qui interviennent dans le domaine.   The cashew sector is expanding rapidly in Benin and is changing the landscape of the area. This study aimed to analyze the spatio-temporal dynamics of cashew plantations in the Sudano-Guinean zone of central Benin from 1991 to 2023 while attempting to understand the various factors that may be causing these changes. To achieve these objectives, multi-date Landsat (1991, 2003, 2013) and Sentinel 2 (2023) satellite data were used to assess the occupancy and rate of change of cashew plantations in the study area. A directed classification using the 'maximum likelihood' algorithm was applied for each image, followed by a post-classification analysis to discriminate between units. The overall accuracy of the classifications obtained was greater than 80%. The results show that plantations have undergone a dynamic evolution in the study area. From 1991 to 2023, the surface area of plantations increased from 304.82 km², or 13.38% of the surface area of the study area, to 342.95 km², or 15.055%. These gradual changes were observed to the detriment of other plant formations, cultivated areas, and water bodies in the study area. This study reveals a process of regression of cultivated land and other vegetation cover units in favor of cashew plantations. Their progressive dynamics also have socio-economic foundations that can be sustained through silvicultural management of the cashew-annual crop system and support from projects/programs and government structures involved in the field