Remote sensing in 2016: What strategy to face new free of access digital resources (spatial images and pedagogical support)
Rudant Jean Paul1, Boudinaud Laure2, Hosford Steven3, Monjoux Eric4, Sarti Francesco5
1 Laboratoire LaSTIG//MATIS, IGN, Université Paris-Est, Marne la Vallée, France
2European Space Agency, France
Abstract. Any contribution, however modest, to the control of free access and free digital resources, will help achieve the overall objective of controlled growth in the « poor » countries. The authors of this paper are interested in the topics « image data » and « training resources ». From a bibliography synthesis and therewith also and especially the interviews with specialists in charge of the development of these resources, present their availability and opportunities before and after 2015 as part of efforts within a group of French training (excluding Europe and Canada) relating to remote sensing and GIS (Geographical Information Systems). They note that the opening to the free use of Decametric resolution radar and optical images of a revolution in the landscape of remote sensing. But the main constraint to overcome for francophone countries outside Europe and Canada remains the internet speed. Overcome this constraint requires some organization, for example to reserve any bandwidth for the upload operation of some nighttime slots where possible. For this revolution landscape of remote sensing continues and is actively involved in development mastered, it therefore appears that freedom of access to images and educational resources related freebies are very positive elements but the couple « Image-educational resources » will be fruitful at the price of an organizational effort based on the principle of the Union is Strength.
Key Words. Geospatial technologies, Remote Sensing, Digital resources, Congo Basin.
Remote sensing and evaluation of soil occupation: case of Faro and Déo department in Adamaoua region
Ndjeuto Tchouli Prosper Innocent1, Aoudou Doua Sylvain2, Tchotsoua Michel1
1: Doctorant, Département de Géographie, Université de N’Gaoundéré
2: Chargé de cours, Institut Supérieur du Sahel, Université de Maroua
Abstract. Faro and Deo department, in the Adamawa region, is a sanctuary for wildlife. Its location between two protected areas gives it a special status. The arboreal wildlife is important and forest are their natural habitats. To face climate change and biodiversity erosion, that are current problems, the preservation of ecosystems is a necessity and it requires an inventory of forest. Remote sensing thus appears as one of the tools that can contribute. This article aims to map and quantify the forest formations in the department of Faro and Deo using free satellite images and free software. As a result, it appears that Shrubby, and wooded savannahs are the dominant type of land use (62.33%) in the Faro and Déo. while the grassland savannas and highland meadows are the least important land use type (2.74%). The forest formations, the arboreal wildlife sanctuary, whose importance here is no longer to be demonstrated, cover about 28% of the area of the department. Their distribution varies depending on the topography. They grow mostly on low and average slope (0 ° to 10 °) on which the combined action of bush fires, overgrazing, favorable climate and deep soil (lateritic), promote the growth of trees. The use of remote sensing in the quantification of resources highlights some limitations such as image resolution, availability of images, and necessity of land work integration to minimize errors. However, remote sensing remains a powerful tool that allows quantification of resources over large areas in a short time but especially in environments where the implementation of traditional methods of quantification of forest formations would be very difficult.
Key word. Remote sensing, cartography, forest formation, Faro and Deo Department.
Remote sensing and mapping of the evolution of land use in the cameroonian plain of the Logone River (2005-2015)
Aoudou Doua Sylvain1
1Institut Supérieur du Sahel, Université de Maroua, Cameroun
Abstract. This study conducted in the plain of Logone Cameroon (located south of Lake Chad, between 10 ° and 12 ° N over a width of sixty kilometers on the meridian 15 ° E) is to determine the changes of land use over a period of 10 years. The analysis is based on the use of Landsat 7 ETM + image data of 1 November 2005 and Landsat8 OLI / TIRS of 5 November 2015. The methodology is based on the diachronic analysis of its images. It is based on a processing chain repeated for each year of observation. The digital processing of satellite images is based on the recognition of objects from field surveys. It shows that the occupation in the plain is experiencing significant changes. It exudes a significant reduction in the steppe about 13 % to the disadvantage of bare soil with a rate of 15% progressing from north to south.
Key Words. Maping, Land cover, Remote sensing, Floodplain, Logone Cameroonian.
Assessment of the Capacity of Carbon Sequestration in the Gallerie Forests of the Mayo Paro Watershed (Tignère Council)
Ndikwé Dourwé Maurice1, Aoudou Doua Sylvain1,2, Talla Tankam Narcisse1,2, Tchotsoua Michel1
1.Laboratoire de Géomatique, FALSH, Université de Ngaoundéré
2.Institut du Sahel, Université de Maroua, Cameroun
3.Laborartoire Automatique, et Informatique Appliquée (LAIA), IUTFV-Bandjoun, Université de Dschang, Cameroun.
Abstract. The forest galleries of the basin pouring the Mayo Paro are dominated to more of 56, 68% of the Berlinia grandiflora. Presenting 17,5 m of height on average, the plant can reach 50 cm of diameter. In each of the 61 placettes of 400 m2 of the 03 retained sites, some summaries have been made. After having characterized the placette, every individual’s size, his/her/its circumference in height of chest, his/her/its GPS references are noted. After the inventory, the volume of wood is determined on the basis of the following formula: V=10*G*P. The treatment of the pictures satellites permitted to discriminate the surfaces covered by the forest galleries of the other types of soil occupation. Of the volume of wood of the forest galleries we passed to the quantity of the carbon sequestrated by these galleries while using the following relation: 1 ton of carbon = 3,667 CO2 tons; either 1ton CO2 = 0,27 ton of carbon = 1 m3de woods. Thereafter the results have been extrapolated on the set of the surfaces occupied by the aforesaid formation of the basin pouring. The forest galleries of the basin pouring the Mayo Paro cover a surface with 26083679, 77 m2 sequestrate 506598,90 tons of carbon in 2015 either 194,22 t / ha. This formation although marginal can participate efficiently to the reduction of the GES in the atmosphere. Their protection proves to be therefore necessary.
Key words. Mayo Paro, Forest gallery, Télédétection, Berlinia grandiflora, Sequestration.
Estimation of the carbon stock of closed vegetation formations of the Department of Vina (Cameroon).
Kouedjou Idriss Landry1, Anaba Banimb Robert Christian1, Mapongmetsem Pierre Marie1, Talla Tankam Narcisse1,2
1. Laboratoire de Géomatique, FALSH, Université de Ngaoundéré,
2. Laboratoire Automatique et Informatique Appliquée (LAIA), IUTFV-Bandjoun, Université de Dschang, Cameroun
Abstract. Forests have been for the past years at the center of many negotiations on climate change. This is due to the fact that deforestation and forest degradation are responsible for emissions of greenhouse gases that affect climate change. In this article, the authors estimate the amount of carbon sequestered by closed vegetation of the plateau Ngaoundéré in the Adamawa-Cameroon. To do this, floristic surveys were performed on 90 plots of 400m². The estimation of woody biomass was calculated from the allometric equation of Brown et al., (1989), adapted by Anderson and Ingram (1993) and Ana-Helena et al.,(2012), which states that « B= » « exp » ⌊ »- 3,1441+0,9719* » « ln » 〖 »(DH » « P » ^ »2″ « *H) » 〗 ⌋. The carbon estimate was based on the recommendation of the IPPC, (2003); Brow and Lugo (1992) which states that carbon in a tree is 50% value in its dry biomass. The results obtained in the plots are generalized to all areas occupied by the closed forests in the region through an expansion factor. It appears that the state of the formations in 2015 sequester about 10 million tons of carbon. This demonstrates the importance of these marginal closed formations of the Congo Basin. As a result, international and national organizations in charge of REDD + must consider them.
Key Word. Biomass, carbon, closed vegetation, image processing, Vina.
Use of UAVs to monitor deforestation and forest degradation in the Congo Basin: state of play and comparative analysis with high-resolution satellite imagery
Sufo Kankeu Richard1, Sonwa Denis Jean2
1 Doctorant, Université du Maine, France.
2 CIFOR, Center for international forestry research
Abstract. The use of even high resolution satellite images by researchers or forestry groups to assess the impacts of deforestation on carbon stocks remains limited due to their cost, availability, quality and human resource. However, recent technological developments have shown that the use of UAVs for the monitoring of deforestation is relevant in many ways. This paper intends to analyse the contribution of drones to the monitoring of the forest cover at the local level and from a comparative analysis to highlight the practical advantages of the images or photos resulting from drones. Based on a fairly extensive literature review on the use of imagery for monitoring natural resources and especially forests, the first step is to compare the characteristics of high-resolution sensor images and then to present the advantages of the images obtained by drones and finally suggest tracks of research on the characterization and the follow-up of the deforestation with the drones in the Congo Basin. Our first analysis show that, apart from the acquisition costs of the physical and software materials, the quality of the images and the final renderings are the major assets of the UAVs. In addition, flight plans and the variation of flight altitudes make it possible to acquire images in a timely manner and with a variable resolution according to the scale of the phenomenon to be studied.
Keywords. UAV, deforestation, Congo Basin, satellite images.
Contribution of satellite imagery to the study of deforestation and forest degradation in the South-West of the Central African Republic
Ouessebanga Aristide Médard
Laboratoire de Climatologie, de Cartographie et d’Etudes Géographie (LaCCEG), Université de Bangui
Abstract. The situation of deforestation and forest degradation in the Central African Republic is much more worrying. One of the major challenges is the disturbing proportion of the increase in climatic variability, particularly of their impacts on the dynamics of forest ecosystems. It seems that the anarchic logging by logging companies on the one hand and by the population on the other hand would be at the origin of the deforestation and the degradation of forests in the southwest of the Central African Republic. The objective of this work is to make a diachronic study using the Landsat TM satellite imagery of December 12, 1984, and ETM + of January 07, 2003 and January 29, 2014, of the forest units of the southwest of the Republic Central African Republic. All these satellite images have for resolution 30 m. For this study, apart from other classification methods, the maximum likelihood that usually provides the classification with the best accuracy is taken into account. The analysis of landscapes from the study of Landsat satellite images shows a significant regression of dense vegetation cover. In the fight against the negative impacts of current climate change, forest protection is essential. While in the past deforestation and forest degradation were equated with the development of agricultural and urban areas, it has become synonymous with an alarming situation on a global scale.
Keywords. Satellite imagery, deforestation, degradation, climate change, forest ecosystems, landscape.
Diachronic analysis of vegetation cover dynamics in a watershed undergoing urbanization: case of Yoyo in Méiganga from 1999 to 2015
Mouhaman Issouhou1, Aoudou Doua Sylvain2, Tchotsoua Michel3
1. Laboratoire de Géomatique, FALSH, Université de Ngaoundéré,
2. Institut Supérieur du Sahel, Université de Maroua,
Abstract. The town of Meiganga, located in the Yoyo Watershed, is currently experiencing an exponential growth of its population resulting in the development of buildings and peri-urban activities such as agriculture, livestock and timber exploitation. This study assesses the dynamics of vegetation cover in this watershed from 1999 to 2015, as well as the factors behind this evolution. The methodology used is based on the delineation of the watershed and the extraction of the hydrographic network using an SRTM image downloaded on Earth Explorer, and on the other hand a diachronic analysis based on the treatment of three scenes Landsat images (two 1999 images and one 2015 images) downloaded from the same site, to produce the various land-use maps and measure the changes made. Plant surveys from plots and transects that served as a training plot for image processing show dominance of Annona senegalensis. The results indicate a sharp deterioration of the forest-galleries and shrub savannas, in favor of the grassy savannas, bare soils and mounts. Thus, on the whole, there is a regressive evolution of plant landscapes between 1999 and 2015 due to the development of road infrastructures which have encouraged the emergence of new activities leading to the spatial extension of the city.
Key words. Dynamic, periphery, average city, diachronic analysis, Meiganga.
Territorial division and forest management of large concessions: how to reconsider the uses of management units to reduce the risks of conflict and pressure on forests in Gabon?
Jean Sylvestre Makak1, Anne Élisabeth Laques2, Louis Marc Ropivia3
1. Geospatial Company (GEOCOM)
2. Institut de Recherche pour le Développement (IRD), France
3. Université Omar Bongo (UOB), Gabon
Abstract. In addition to the production areas of timber and biodiversity conservation, forest management of large concessions in Gabon also includes agroforestry series occupied by rural communities. Although « recognized » as an integrated territorial domain in the dealer’s planning documents, the process of demarcation of village territories remains the fruit of decisions and individual actions at the initiative of the forest operator. This article discusses how from satellite images and a spatial analysis conducted in consultation with local stakeholders (forest and rural communities), a co-constructed zoning can reduce the risk of conflict activities and forest degradation. The resulting methodological proposal is based on the case of local communities in Guietsou, forest management unit of the Wood Company of Gabon (CBG), in the southwest of Gabon. The main result is to expose the steps of the participatory demarcation of forest areas shared with village communities. This methodological proposal is based on the case of the forest management unit Mandji southeast Gabon, Wood Company of Gabon (CBG) concession. The main result is to expose the steps of the participatory demarcation of forest areas shared with local communities.
Key Word. Forest management, local territorial division, satellite imagery, participatory approach, Gabon
Allometric equations for estimating the above-ground biomass of western highland savanna – Cameroon
Wouokoue Taffo Junior Baudoin, Nguetsop Victor François, Fonkou Théophile
Laboratoire de Botanique Appliquée, Département de Biologie Végétale, Faculté des Sciences, Université de Dschang, Cameroun.
Abstract. Savannas ecosystems are significant terrestrial carbon stocks and their quantification is crucial to understand the total impact of the climate changes.The aim of this study was to formulate the mono and multi-specific allometric equations for evaluating the woody biomass of Western Highlands savannas of Cameroon. Data of aboveground woody biomass were obtained from destructive sampling of 103 trees belonging to seven (07) species of diameter ≥ 5 cm on plots of 0.04 ha. Proportional relationships between aboveground biomass and diameter at breast height were constructed from 8 allometric models (linear, growth, compound, exponential, quadratic, cubic, power and logarithmic). From the data collected and analyzed, 2 allometric models are suggested based on quadratic and cubic regressions. Carbon stock assessment based on these models gave results with high coefficient of determination r² > 0.9. ANOVA tests showed a very low difference between mean values of experimental data and model outputs. The results show that the greatest risks of skew are located at the level of individuals of large diameter (> 21 cm) whereas good prediction of the biomass is on individuals of small diameters (< 21 cm) which are dominant in the ecosystems of savanna. Specific models are more efficient in estimating biomass than models taking in account several species.
Keywords. Aboveground biomass, Cameroon, Diameter at breast height, Allometric equations, highland savannas.
Characterization and spatial dynamics of vegetation cover in Togo’s protected areas: Satellite remote sensing study on the Missahoé classified forest in the plateaux region
Komivi Messan Akakpo1,2,3, Jacques Quensiere3, Sébastien Gadal2, Kossi Adjonou4, Kouami Kokou4
1 Laboratoire CEMOTEV, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), France
2 Aix-Marseille Univ, Univ Nice Sophia Antipolis, Avignon Université, CNRS, ESPACE, Nice, France
3 UMI Résiliences, IRD France Nord, Bondy, France
4 Laboratoire de botanique et écologie végétale, Université de Lomé, Togo
Abstract. Protected areas are privileged spaces for reflection on the conservation of nature and the place of human being. In Togo, these areas are affected by degradation and forest cover loss. This study is part of research on forest cover dynamics in Togo. It helps to know more about current state and spatial dynamics of forest cover in protected areas of the country, particularly in the Classified Forest of Missahoé (FCM) in the « Plateaux Region ». It is based on remote sensing and aims at quantifying changes in the land uses of this protected area since 1980, with the use of three Landsat TM, ETM+, OLI imageries from years 1987, 2002 and 2015. The methodology is based on the characterization of land uses and the study of their areas dynamics at the three selected dates, by remote sensing. For this purpose, a typology of land uses was established. It distinguishes (1) agroforests (an association of forest trees and perennial crops such as coffee, avocado and other fruit trees), (2) mosaic of savannah, fallow and food crops (shrub, fallow and food crops), (3) dense forests, and (4) other types of forests (woodlands, mainly). The results allow to say that perennial and seasonal crops production is one of the most common activities in FCM. It concerns at least half of the forest area for about 30 years. The results also mean that management or reforestation efforts were provided from 2000 to 2010, both by the government and local development organizations. They allowed to slightly increase the forest cover in the FCM. However, they still face local actors strategies that explain the specific changes in each land use class. This confirms that there is no sustainable natural resources conservation without local development. Therefore, the role and the functioning of protected areas in Togo must be modernized.
Key words. Protected areas, spatial dynamics, Classified Forest of Missahoe, Togo
Some methodological approaches for the determination of albedo in Congo agrosystems
Moundzeo L., Moutsouka F., Loutete–Bahouamio R. D., Mondzali-Lenguiya R.
Institut National de Recherche Agronomiques (IRA)
Abstract. Within the framework of a bearing project on the dynamics of productivity of the agro system in Congo, a study has just been realized by the Agronomic National Research Institute (IRA) in the agro system of Mayombe and the eucalyptus’s plantations of the Littoral. The objective of this study is to estimate the albedo starting from the empirical expressions and to compare their evolution in both agro system. The data used in this study, cover one period of more than 60 years (1932-2014). They come from the weather stations of Dolisie for Mayombe and Pointe-Noire for the eucalyptus’s plantations of the Littoral. It is the sunstroke, of the temperatures of the air and the ground from which, the various types of solar radiation were estimated and the albedo, deduced from four (4) empirical expressions. The standard deviation, the variation and correlation coefficients are given to appreciate the discrepancy between the various empirical expressions. The results show that in both agro system, the albedo is about 0.03 to 0.32, the standard deviation is from 0.028 to 0.136, the coefficient of variation from 20 to 70% and the coefficient of correlation from 0.651 to 0.998. This study deserves to be continued in all the agro system of the country. It will have to be based on a coupling with the satellite pictures to confirm the capacity of the models used.
Key words. Albedo, agro system, empirical expressions, weather data, Congo.
Remote sensing and mapping of the national forest cover of Togo: pilot study within the ODEF for the establishment of the Permanent Observatory of Forests
Arifou Kombate1, Jean-Pierre Chery2 Benoit Mertens3
1. Direction Générale de l’ODEF, Lomé, TOGO
2. AgroParisTech-SIAFEE/UMR TETIS, Montpellier, France
3. UMR 228 Espace Dev/IRD, Montpellier, France
Abstract. Faced with the rapid degradation of forest resources in Togo because of unplanned operations and inadequate reforestation, the difficulties in assessing the impact of the Reforestation and Logging Office’s (ODEF) activities on the change in national forest cover led this office to make use of remote sensing tools. The study funded by the GEOFORAFRI program has achieved the land use mapping in the classified forests (Eto, Haho-Baloe, Lilicope and Wouto) from an unsupervised classification of SPOT images of December 2013. The land use maps developed in this study may well help to decision making in the upcoming preparations of annual plans of operations of reforestation and forest management. This Work allowed ODEF and the forestry administration of Togo to have a methodological basis of satellite images processing in order to know the level of change in forest cover in some classified forests of the country.
Key words. Degradation, remote sensing, methodology, forest cover, Togo