Dynamique Passée et Récente et Prévision de L’occupation du Sol: cas du Bassin Versant de la Lobo (Centre – ouest de le Côte d’Ivore)

Le développement agricole et la forte croissance démographique ont contribué à la perte du couvert forestier ivoirien. L’objectif de cette étude est d’analyser l’évolution passée (1986 à 2019) et de prédire (2019 à 2050) l’occupation des sols dans le bassin versant de la Lobo. La classification supervisée par maximum de vraisemblance des images landsat de 1986, 2003 et 2019, couplée à la méthode intensity analysis a été appliquée dans cette étude. Les résultats montrent sur la période de 1986 à 2019 une baisse de la végétation de 4708,82 km2 à 4054,72 km2 au détriment de l’augmentation de la mosaïque des cultures et jachères de 6376,56 km2 à 6925,05 km2. Les plans d’eau et sols nus et bâtis ont également augmenté respectivement de 3,73 km2 et 101,88 km2. Par contre, les aires protégées sont restées inchangées avec une superficie de 1516,13 km2. Les changements des classes d’occupation du sol par intensity analysis ont été lent au premier intervalle de temps (1986-2019) mais s’accéléront au deuxième intervalle de temps (2019 à 2050). La mosaïque des cultures et jachères et la végétation ont connu respectivement des pertes de superficies moins intenses et plus intense, tandis que les autres classes ont gagné intensément de superficies durant le premier intervalle de temps. Pendant le deuxième intervalle de temps, seuls les plans d’eau et la mosaïque des cultures et jachères connaîtront des intensités de gains de superficies moins intenses. Il n’y a pas eu de transition des autres classes vers la végétation et la mosaïque des cultures sur toute la période d’étude (1986 à 2050).               Agricultural development and high demographic growth have contributed to the loss of ivorian forest cover. The objective of this study is to analyse the past (1986 to 2019) and  to predict (2019 to 2050) evolution of land use in the Lobo watershed. Supervised maximum likelihood classification of landsat images from 1986, 2003 and 2019, coupled with intensity analysis was applied in this study. The results show a decrease in vegetation from 4708.82 km2 to 4054.72 km2 over the period 1986 to 2019 at the expense of an increase in the mosaic of crops and fallow land from 6376.56 km2 to 6925.05 km2. Water bodies and bare and built-up land also increased by 3.73 km2and 101.88 km2 respectively. Protected areas, on the other hand, remained unchanged at 1516.13 km2. Changes in land use classes by using intensity of analysis were slow in the first time interval (1986-2019) but will accelerate in the second time interval (2019 to 2050). Crop and fallow mosaic and vegetation experienced less intense and more intense area losses respectively, while the other classes gained area intensively during the first time interval. During the second time interval, only water bodies and the crop-fallow mosaic will experience less intense area gains. There was no transition from the other classes to vegetation and crop mosaic over the entire study period (1986 to 2050)

Map errors that could account for deviations from a uniform intensity of land change

Intensity Analysis is a mathematical framework that compares a uniform intensity to observed intensities of temporal changes among categories. Our article summarizes Intensity Analysis and presents a new method to compute the minimum hypothetical error in the data that could account for each observed deviation from a uniform intensity. A larger hypothetical error gives stronger evidence against a hypothesis that a change is uniform. The method produces results for five groups of measurements, which are organized into three levels of analysis: interval, category, and transition. The method applies generally to analysis of changes among categories during time intervals, because the input is a standard contingency table for each time interval. We illustrate the method with a case study concerning change during three time intervals among four land categories in northeastern Massachusetts, USA. Modelers can perform the analysis using our computer program, which is free. © 2013 Taylor & Francis

Characterizing degradation gradients through land cover change analysis in rural Eastern Cape, South Africa

CITATION: Munch, Z., et al. 2017. Characterizing degradation gradients through land cover change analysis in rural Eastern Cape, South Africa. Geosciences, 7(1):7, doi:10.3390/geosciences7010007.The original publication is available at http://www.mdpi.comLand cover change analysis was performed for three catchments in the rural Eastern Cape, South Africa, for two time steps (2000 and 2014), to characterize landscape conversion trajectories for sustained landscape health. Land cover maps were derived: (1) from existing data (2000); and (2) through object-based image analysis (2014) of Landsat 8 imagery. Land cover change analysis was facilitated using land cover labels developed to identify landscape change trajectories. Land cover labels assigned to each intersection of the land cover maps at the two time steps provide a thematic representation of the spatial distribution of change. While land use patterns are characterized by high persistence (77%), the expansion of urban areas and agriculture has occurred predominantly at the expense of grassland. The persistence and intensification of natural or invaded wooded areas were identified as a degradation gradient within the landscape, which amounted to almost 10% of the study area. The challenge remains to determine significant signals in the landscape that are not artefacts of error in the underlying input data or scale of analysis. Systematic change analysis and accurate uncertainty reporting can potentially address these issues to produce authentic output for further modelling.http://www.mdpi.com/2076-3263/7/1/7Publisher's versio

Land classification and change intensity analysis in a coastal watershed of Southeast China

The aim of this study is to improve the understanding of land changes in the Jiulong River watershed, a coastal watershed of Southeast China. We developed a stratified classification methodology for land mapping, which combines linear stretching, an Iterative Self-Organizing Data Analysis (ISODATA) clustering algorithm, and spatial reclassification. The stratified classification for 2002 generated less overall error than an unstratified classification. The stratified classifications were then used to examine temporal differences at 1986, 1996, 2002, 2007 and 2010. Intensity Analysis was applied to analyze land changes at three levels: time interval, category, and transition. Results showed that land use transformation has been accelerating. Woodland's gains and losses were dormant while the gains and losses of Agriculture, Orchard, Built-up and Bare land were active during all time intervals. Water's losses were active and stationary. The transitions from Agriculture, Orchard, and Water to Built-up were systematically targeting and stationary, while the transition from Woodland to Built-up was systematically avoiding and stationary. ? 2014 by the authors; licensee MDPI, Basel, Switzerland

Intensidad en los cambios de usos del suelo registrados en la Comunidad de Madrid durante los años 1982 y 2006

Se realiza un análisis jerárquico de intensidad de cambios de usos del suelo, a nivel de intervalo de tiempo, a nivel de categorías y a nivel de transiciones, aplicado a la Comunidad de Madrid para los años 1982, 1990, 2000 y 2006. Se observan los principales procesos de cambio y qué categorías se han mostrado estables. Las zonas de extracción minera, vertederos y en construcción son las más intensas, en pérdidas y en ganancias. La artificialización del territorio está relacionada con el aumento de la accesibilidad por infraestructuras de transporte y con la pérdida de superficie agrícola

Analyzing Variations in Size and Intensities in Land Use Dynamics for Sustainable Land Use Management: A Case of the Coastal Landscapes of South-Western Ghana

Land use/land cover change (LULCC) studies are gaining prominence among environmentalist and land use planners. This is due to the effects of LULCCs on natural ecosystems and livelihoods. In the coastal landscape of south-western Ghana, there exist knowledge gaps in the variations in size and intensities in LULCCs and the degree of change among land cover types in LULCC studies. Such studies are important for identifying periods of rapid land cover transitions and their implications on the landscape. Using change detection, intensity analysis and informal stakeholder conversations, the land use system dynamics of the study landscape was analyzed over a 34-year period to assess the variations in size and intensities in LULC transitions and its implications. The results showed a dynamic landscape driven primarily by rubber and settlement expansions. Rubber and settlement increased threefold (172.65%) and fourfold (449.93%) in the 34-year period mainly due to rubber outgrower scheme and onshore infrastructural developments, respectively. Gains in rubber and settlement targeted arable lands. The LULCC implies local food insecurity issues, declines in ecosystem services and compromised livelihoods, hence, the enforcement of the Land Use and Spatial Planning Act (2016) is recommended in land use planning in the coastal landscapes of south-western Ghana.German Academic Exchange Service (DAAD)Peer Reviewe

Linking pattern to process: intensity analysis of land-change dynamics in Ghana as correlated to past socioeconomic and policy contexts

Spatio-temporal analysis of transitions in land cover is critical to understanding many ecological challenges, especially in environmentally vulnerable regions. For instance, in Sub-Saharan Africa, large-scale cropland expansion is expected due to the increasing demand for fuel, food, and fibre. Clearing land for cropland expansion is a driving factor in the degradation of natural ecosystems. We present a spatio-temporal analysis of land-cover change in Ghana’s Northern, Upper East, and Upper West provinces using Intensity Analysis on the periods from 1992 to 2003 and 2003 to 2015. The objectives of this study were to determine whether the intensity of land-use and land-cover (LULC) change is consistent between the two periods and to investigate the direction and extent of change for different LULC categories in northern Ghana. The methodology measures land-cover changes at the interval, category, and transition levels. The results suggest that the annual rate of land change was higher between 1992 and 2003 compared to that between 2003 and 2015. Furthermore, the category-level analysis reveals that the gains in the arable land and tree/forest-cover classes during both time intervals were higher than the uniform intensity. The transition-level analysis results indicate that most of the gains in arable land and tree/forest-cover came at the cost of semi-arid shrublands during both periods. There is also evidence of local increases in forest-cover, likely linked to afforestation policies established by the Ghanian government; however, overall, there has been a loss of natural habitat. The study provides data to improve our understanding of the magnitude and direction of land-cover change, essential for the development of policies designed to mitigate the impact of land-cover change on the livelihoods of local people and the environment at the national and sub-national levels

Discussing Changes in Historical Human–Environmental Dynamics Through Ecosystem Services Interactions and Future Scenarios in a Rural-Mining Region of Central Appalachians

The aim of this dissertation was to investigate how recent processes of land-change induced by humans contributed to the shaping and alteration of the current landscape in a headwater system of Central Appalachians in West Virginia (US), to understand the interactions and tradeoffs among ecosystems services and address potential solutions for targeting more sustainable human-environment interactions in a region that is deeply grounded on extractive economies. The multitiered objective was addressed through different research phases in order to unfold and disentangle a series of complex problems that the study area presents. Three main phases were used; they corresponded to distinct chapters within this study. The first paper analyzed land-cover transitions, from 1976 to 2016, using Multi-Level Intensity Analysis and Difference Components methods. Two land cover classifications were derived explicitly for this study using remote sensing methods and obtained with segmentation analysis and machine learning algorithms from historical high-resolution aerial images (1-2 meters) and ancillary data. Results allowed the author to distinguish between surface mining areas produced before and after the enactment of the Surface Mining Control and Reclamation Act (SMCRA, 1977), discuss differences among distinct socio-technical phases, and differentiate the main drivers and outcomes of landscape change processes in the area. The historical information and knowledge gained in the first step were used to inform the second chapter, whose objective was to analyze the interactions among ecosystem services and derive their bundles. Ecosystem services models were obtained using InVEST, and a custom model was explicitly defined to link water quality changes to freshwater ecosystem services. The results identified significant losses of carbon sequestration, habitat quality, and freshwater ecosystem services in areas subjected to Mountaintop Removal mining. The findings spatially located different ecosystem services bundles characterized by distinct human-environment relationships and complex anthropogenic drivers not limited to coal mining processes. The study identified the appropriate spatial scale for targeting specific management actions and implementing conservation, as well as development-restoration strategies, in areas characterized by similar social-ecological processes and deeply altered ecosystems. In the third essay, the identification of ecosystem services bundles allowed the author to delineate two distinct social-ecological systems characterized by surface coal extraction and reclamation processes produced during different historical phases. These areas were discussed as separate case studies within a time interval of seventy years, from the recent past (1976) to future scenarios (2045). The scenarios were based on a backcasting approach integrated by ecosystem services models and the analysis of functional changes within the two social-ecological units analyzed. The results highlighted differences in the flow of ecosystem services due to the intensity of mining and the different and incremental reclamation approaches used in the scenarios. The comparison of threats and opportunities within each scenario, identified, in the discussion section, a range of plausible hypotheses and solutions the stakeholders and communities of the region should face if they want to rehabilitate the social and ecological conditions to promote a more sustainable approach for the future of these places

Étude d’impacts de la dégradation des terres liée à la désertification sur le paysage et le volet socio- économique dans la région de M’Sila, Algérie Est

Cette thèse porte sur l’étude de l’impact de la désertification sur les paysages steppiques et le volet socio-économique dans une zone steppique aride (Sud de la Wilaya de M’sila, Algérie) fortement exposée à ce phénomène. Malgré l’intervention de l’État depuis des décennies à travers les programmes de développement de la steppe qui visent à renforcer la capacité des ménages à gérer les risques sur le long terme. A travers cette étude, nous avons essayé de montrer l’apport de l’utilisation de la télédétection et du système d’information géographique pour la caractérisation de l’état de l’occupation du sol et son évolution spatio- temporelle à partir des traitements effectués sur une série d’images satellitaires de Landsat de différentes dates (1984 et 2020). Les résultats de l'observation du terrain montrent qu'il existe de différents signes de désertification et de dégradation des terres dans la zone d'étude, jugés par le changement des modes d'utilisation des terres et les types du couvert végétal. Ces changements indiquent qu'il y a une grande dégradation mise en évidence dans l'extension du parcours dégradé et la régression des surfaces steppiques et parcours. De plus, le phénomène de l’ensablement a augmenté ces dernières années dans la zone affectée par rapport à la superficie totale de la zone étudiée de 1,21% en 1985 à 2,93% en 2020. D’autre part, bien que l’agriculture soit quelque peu développée dans la zone d’étude, l’environnement désertifié l’a empêchée de donner des résultats escomptés. Ceci est contraignant pour les exploitants dans l’atteinte de leurs objectifs. Les techniques d’exploitation agricole non appropriées utilisées par les exploitants, associées de nos jours aux effets des phénomènes météorologiques extrêmes, entraînent une dégradation ininterrompue du potentiel productif des terres agricoles et de l’environnement d’une façon générale. Les problèmes et les contraintes des activités agricoles dans la zone d’étude sont diversifiés, tels que la faiblesse de la productivité, l’insuffisance des infrastructures et des matériaux agricoles, la hausse du coût de la production, les problèmes liés à l’irrigation, le manque d’équipements agricoles, le manque d’électricité, le faible niveau d’instruction ….etc. La propriété foncière et les droits fonciers des exploitants constituent une contrainte à l'adoption des techniques de gestion collective des ressources naturelles. Les résultats sur l’aspect socio-économique de la désertification montrent une situation défavorable. Les revenus agricoles baissent en raison du coût de la vie très élevé. De plus, on a remarqué que la psychologie des populations vivant à proximité des sites est relativement sensible à la désertification qui cause la dégradation du couvert végétal, l’appauvrissement des sols, la baisse des rendements agricoles, et le déboisement de nouveaux espaces agricoles Les efforts ne manqueront pas pour compenser cette situation. Donc, il s'agit de projets de développement de l'agriculture et de l'élevage, et des interdictions visant à préserver la végétation et atténuer le processus de dégradation des terres lié à la désertification des sols