References of "Djaby, Bakary"
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See detailBulletin agrométéorologique - Situation au 30 avril 2009
Tychon, Bernard ULg; Djaby, Bakary ULg; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2009), 7(1), 1-3

Alors que l’on pouvait craindre les conséquences de l’hiver froid que nous avons connu cette année, il apparaît, au niveau de nos indicateurs météorologiques et de nos indicateurs spatiaux dérivés de la ... [more ▼]

Alors que l’on pouvait craindre les conséquences de l’hiver froid que nous avons connu cette année, il apparaît, au niveau de nos indicateurs météorologiques et de nos indicateurs spatiaux dérivés de la télédétection, que les grandes cultures ont dans l’ensemble bien passé l’hiver et elles ont largement rattrapé le retard accumulé au cours des mois d’hiver et du tout début de printemps. Ceci se vérifie également sur le terrain où les stades phénologiques sont très proches de la situation normale. Aucune prévision de rendement n’est faite à ce stade. [less ▲]

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See detailSet-up of CGMS in Ethiopia and first user experiences
Djaby, Bakary ULg; Tychon, Bernard ULg; Massart, Michel

Conference (2009, March 18)

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See detailTrends in productivity of crops, fallow and rangelands in Southwest Niger: Impact of land use, management and variable rainfall
Hiernaux, Pierre; Ayantunde, Augustine; Kalilou, Adamou et al

in Journal of Hydrology (2009), 375 (1-2)

To document trends in land use and herbaceous production, 71 field sites sampled among cropped fields, fallow fields and rangelands in the Fakara region (Niger) were monitored from 1994 to 2006. The ... [more ▼]

To document trends in land use and herbaceous production, 71 field sites sampled among cropped fields, fallow fields and rangelands in the Fakara region (Niger) were monitored from 1994 to 2006. The overall trend in land use confirmed the historical increase of the cropped areas since mid 20th century, at an annual rate of 2% from 1994 to 2006. This trend is the result of changes in the relative extent of fields permanently cropped and fields under shifting cultivation, and for the latter, the relative proportion of short (3 years) and long (10 years) duration fallows. Type of land use together with topography and soil type determine the herbaceous production and the resulting yield measured towards the end of the wet season. The variation in site yields between years is of the same order of magnitude as the variation in yields between sites within a year. There is an overall decreasing trend in site yields by 5% annually from 1994 to 2006 that is not explained by variations in rainfall. The decreasing trend is observed on fields under shifting cultivation, fallowed fields and rangelands, although not all sites are equally affected. Causes are likely to be multiple which might include changes in land use, decline of soil fertility and increased grazing pressure. Indeed, the remaining rangelands on marginal land and the fallows still accessible to livestock are subject to such a heavy grazing during the rainy season that the herbaceous standing mass measured at the end of the season reflects poorly the actual production. After the two first years of cropping, the herbaceous yield in fields under shifting cultivation with no fertilisation is negatively affected by the number of successive years of cropping. Moreover, clearing fallow after a decreasing number of years affects the mean herbaceous yield of fallowed fields by reducing the contribution of more productive old fallows. Changes in land use, grazing pressure and soil fertility also triggered changes in species composition with a strong reduction in diversity from rangelands to fallows, and again from fallows to cropland weeds. No correlations was found however between productivity and species composition. Cumulative rainfall does not explain between site or between year deviations in herbaceous yield even when sites are sorted by land use type or by soil type in the case of fallow and rangelands. Simulated production calculated with the STEP model does not explain herbaceous yields much better even when sites are grouped by land use and soil type. However, relative changes of herbaceous yields are reasonably predicted on sites that remained fallowed and were not heavily grazed for at least four consecutive years. [less ▲]

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See detailGlobal agricultural monitoring systems by integration of earth observation and modelling techniques (globam project).
Defourny, Pierre; Bériaux, Emilie; Tychon, Bernard ULg et al

Conference (2008, February 12)

Nowadays, food security and crop production variability become a major concern. Moreover, in spite of major technological and methodological EO improvements observed since the late 1990’s, very little ... [more ▼]

Nowadays, food security and crop production variability become a major concern. Moreover, in spite of major technological and methodological EO improvements observed since the late 1990’s, very little change has been observed in the operational systems. A major gap exists between the remote sensing operationally used and the current scientific state of the art in EO crop monitoring. There is a lack of relevant field data over large areas, and these data are very much needed to gain a better understanding of potential improvements of the operational systems. [less ▲]

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See detailLes Zones à risque environnementales et socio-économiques - ZARESE
Di Vecchia, Andrea; Djaby, Bakary ULg; Bacci, Maurizio et al

Report (2006)

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See detailVulnerability Assessment for Food Crisis Management in the Sahel Region
Bacci, Maurizio; Filippis, Tiziana; Vecchia, Andrea et al

in Oosterom, Peter; Zlatanova, Siyka; Fendel, Elfriede M. (Eds.) Geo-information for Disaster Management (2005)

In the Sahel region the unfavourable climatic conditions and the natural resources degradation are recognised to be the main constraints affecting the agricultural productivity; nevertheless more complex ... [more ▼]

In the Sahel region the unfavourable climatic conditions and the natural resources degradation are recognised to be the main constraints affecting the agricultural productivity; nevertheless more complex and less evident causes of food insecurity of population groups need to be investigated. [less ▲]

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See detailA Review of Agrometeorological Monitoring Tools and Methods Used in the West African Sahel
Traore, Seydou; Sidibe, Brahima; Djaby, Bakary ULg et al

Scientific conference (2004, March 23)

Agrometeorological monitoring in the Sahelian countries consists of collecting, processing, and analyzing various data and information that can affect the outcome of the agricultural season. It combines ... [more ▼]

Agrometeorological monitoring in the Sahelian countries consists of collecting, processing, and analyzing various data and information that can affect the outcome of the agricultural season. It combines observational data from national meteorological, hydrological, agricultural extension, plant protection, and livestock breeding offices, as well as satellite data provided by the AGRHYMET Center. From May until the end of October, multidisciplinary working groups (MWGs) in each country publish dekadal and monthly bulletins. At the regional level in the AGRHYMET Center, data and information coming from the national components are combined with satellite data to elaborate regional syntheses that are published at different time steps. In these publications, the current situation is analyzed and compared with that of the previous period, the previous year, and the average. Forecasts of seasonal rainfall and crop yields, that are refined from month to month, are also given. Color maps illustrates the amounts of rainfall, sowing dates, crop water requirements, satisfaction indices, yield estimates, zones with particular pests, and the advance of the vegetation front. Hard copies and electronic versions of these publications are mailed to subscribers. They are also posted on the Center’s website: www.agrhymet.ne. [less ▲]

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See detailSuivi de la végétation en zone sèche par des produits d‘information dérivés de l‘imagerie spatiale
Crépeau, Christian; Bennouna, Taoufiq; Bicheron, Patrice et al

in Science et changements planétaires / Sécheresse (2003), 14(1), 56-57

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See detailLes crises alimentaires et les systèmes de prévision au Sahel
Andrea, Di vecchia; Patrizio, Vignaroli; Djaby, Bakary ULg

Conference (2002)

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See detailTHE ESTIMATION OF THE HERBACEOUS BIOMASS IN THE SAHELIANS PASTORAL ZONES USING A GIS
TIZIANA, DE FILIPPIS; Djaby, Bakary ULg; BRAHIMA, KONE et al

in Gérard, Bégni (Ed.) Observing our environment from space: new solutions for a new millennium (2001)

In the Sahel region the pastorals resources are strongly linked to the fluctuation of the biomass production and as well as the breeding systems, which are based on the transhumance and the nomadism as ... [more ▼]

In the Sahel region the pastorals resources are strongly linked to the fluctuation of the biomass production and as well as the breeding systems, which are based on the transhumance and the nomadism as well. In the present study, an integrated approach of multi-source, multi-type and multi-scales data analysis in the pastoral zone in Senegal, Mali, Burkina Faso, Mauritania, Niger and Chad has been developed using PC-Arc/Info and Arc/View potentialities for the purpose of Sahelian rangeland production estimation. [less ▲]

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See detailLes aptitudes agricoles et pastorales des sols dans les pays du CILSS
Djaby, Bakary ULg; Koné, Brahima; Labo, Moussa et al

Report (2001)

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See detailUtilisation de la télédétection pour le suivi des parcours en zone agro-pastorale sahélienne
Djaby, Bakary ULg

Master of advanced studies dissertation (2000)

L'importance des terres de parcours au Sahel a depuis les sécheresses, favorisées l'observation des ressources pastorales par la télédétection basse résolution. Parmi les indices de végétation issus des ... [more ▼]

L'importance des terres de parcours au Sahel a depuis les sécheresses, favorisées l'observation des ressources pastorales par la télédétection basse résolution. Parmi les indices de végétation issus des images fournies par les différents senseurs, le NDVI est le plus couramment utilisé. Plusieurs travaux ont montré que cet indice est affecté par les variations des propriétés spectrales des sols. Cette caractéristique limite la détection de la végétation dans les milieux à couvert végétal faible comme en zone agropastorale sahélienne. Afin de pallier cette insuffisance du NDVI, plusieurs autres indices ont vu le jour comme le TSAVI dont les caractéristiques se sont montrées performantes en milieu expérimental pour le suivi de la végétation éparse. Au cours de ce travail, le TSAVI est élaboré et utilisé en mode opérationnel en comparaison avec le NDVI. Les deux indices utilisés sont issus des images de SPOT-VEGETATION, le nouveau senseur européen opérationnel depuis 1998. Cette comparaison est faite à travers l'évolution au cours de la saison des deux indices et l'évaluation de la phytomasse herbacée dans un milieu où l'occupation des sols est connue. Les résultats obtenus montrent que le TSAVI diffère très peu du NDVI au cours de la période de végétation active. Les différences observées résident dans la capacité du TSAVI à identifier les zones d'émergence précoce de la végétation, en début de saison des pluies. Dans une classification supervisée avec la signature indiciaire des sols de la région du Fakara, le TSAVI se montre plus performant avec une erreur d'omission inférieure de 10% à celle du NDVI. Dans l'évaluation de la phytomasse herbacée, les relations obtenues montrent que le NDVI est plus indiqué que le TSAVI. Malgré l'utilisation de données sur l'occupation des sols, les relations obtenues entre les indices et les masses végétales sont faibles. Cette faiblesse des relations est en partie liée au morcellement du territoire en milieu agropastoral sahélien. En revanche, dans les zones qui apparaissent homogènes, les résultats indiquent des liaisons fortes entre les indices et la masse végétale des mauvaises herbes. Les zones agropastorales du Sahel semblent plus indiquées dans un suivi qualitatif avec la télédétection basse résolution. La complexité de l'occupation des sols liée à plusieurs facteurs peut cependant être abordée avec une combinaison télédétection haute résolution et basse résolution pour une amélioration de l'information sur la sécurité alimentaire au Sahel. [less ▲]

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See detailUso di immagini GAC NDVI per la previsione dei rendimenti agricoli in Aree Saheliane
Romanelli, Stefano; Lorenzo, Bottai; Andrea, Di Vecchia et al

in Rivista Italiana di Telerilevamento (1997), 11

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See detailL’enquête nationale sur les effectifs du cheptel au Burkina Faso
Bahili, Jean; Djaby, Bakary ULg

in Stateco (1993), 73

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