APPORT DE LA TELEDETECTION AEROSPATIALE POUR L'AIDE A LA GESTION DE LA SOLE CANNIERE REUNIONNAISE

M. S. BALDY, M. J.C. AUTREY, M. C. PUECH, M. J.M. STRETTA, Mme A. BEGUEThe objective of this thesis is to study the potentialities of remote sensing for sugarcane crop management in Reunion Island. We used a data base of multi-temporal SPOT 4&5 images (2002-2003) and we set up an hyper-spectral CASI campaign in September 2002. At the same time, we organized ground measurements to follow the evolution of sugarcane biophysical parameters (leaf area, nitrogen rate, fresh biomass) and agronomic parameters (harvests and re-plantings). The results shows that it is possible to estimate leaf area (LAI) using the normalized difference vegetation index (NDVI). We also has highlighted the possibility of estimating the cane yield starting from the vegetation index NDVI calculated at the time of maximum development of the cover. Using the SPOT data, yield estimates, on a field scale, could be improved by combining the growth model Mosicas and leaf area evolution obtained from the SPOT 4&5 images series. The hyper-spectral CASI data give a better estimate of the leaf area and fresh biomass than SPOT 4&5 data, with an estimate of the leaf nitrogen content which is, in phase of maturation, an indicator of sugar concentration. The ability to discriminate sugarcane fields according to their surface (full vegetation, cut or bare soil) has allowed to develop dynamic cartography of the sugarcane fields at the regional scale in near real time : the harvest and the replanting follow-ups.L'objectif de cette thèse est d'étudier les potentialités de la télédétection aérospatiale pour l'aide à la gestion de sole cannière Réunionnaise. Nous avons utilisé une base de données d'images multitemporelles SPOT 4&5 (années 2002 et 2003) et organisé une campagne d'acquisition d'images hyperspectrales CASI en septembre 2002. Simultanément, nous avons assuré le déroulement et la mise en place d'un protocole de mesures au champ pour suivre l'évolution des paramètres biophysiques descriptifs de l'état du couvert de la canne (surface foliaire, taux d'azote, biomasse de la culture) et des paramètres agronomiques (suivi des coupes et des replantations). Les résultats ont montré qu'il est possible d'estimer la surface foliaire (LAI) à partir de l'indice de végétation normalisé (NDVI) ainsi que le rendement canne à partir de l'indice de végétation NDVI calculé au moment du développement maximal du couvert. Avec les données SPOT, la meilleure estimation du rendement canne à l'échelle parcellaire résulte du couplage entre le modèle de croissance Mosicas et les profils d'évolution de surface foliaire obtenus à partir des images SPOT 4&5. Les données hyperspectrales CASI permettent une meilleure estimation de la surface foliaire et de la biomasse fraîche que les données SPOT 4&5 ainsi qu'une estimation du taux d'azote foliaire qui est, en phase de maturation, un indicateur de richesse en sucre. La possibilité de discriminer des parcelles de canne en fonction de leurs états de surface (pleine végétation, coupée ou labourée) nous a permis de développer des applications opérationnelles de cartographie dynamique de la sole cannière en temps quasi réel : le suivi des coupes et des replantations

Improving harvest and planting monitoring for smallholders with geospatial technology: the Reunion Island experience

8 pagesInternational audienceWith the recent development of geospatial technologies, remote sensing data are more and more integrated in the information systems of crop industries. The satellite's ability to collect "snapshots" over large cropped areas at once makes it a unique tool to able it to acquire localized and objective data in real-time.In this paper, we present how this technology can provide reliable information for sugarcane planting and harvest monitoring by updating information on field/blocks boundaries and cane status using time series of satellite images. Through the experience conducted on Reunion Island (Indian Ocean) where the sugar industry has difficulty collecting updated localized information on smallholders fields, we show how SPOT satellite images can be interpreted and processed in order to produce thematic maps and statistics. These maps can then be integrated in a Geographic Information System (GIS) designed for decision makers. This on-the-shelf GIS permits one to visualize maps and edit monthly statistics of the management practices in each production area

Apport de la télédétection aérospatiale pour l'aide à la gestion de la sole cannière réunionnaise

The objective of this thesis is to study the potentialities of remote sensing for sugarcane crop management in Réunion Island. We used a data base of multi-temporal SPOT4&5 images (2002-2003) and we set up an hyper-spectral CASI campaign in September 2002. At the same time, we organized ground measurements to follow the evolution of sugarcane biophysical parameters (leaf area, nitrogen rate, fresh biomas) and agronomic parameters (harvest and re-plantings). The results shows that it is possible to estimate leaf area (LAI) using the normalized difference vegetation index (NDVI). We also has highligted the possibility of estimating the cane yield starting from the vegetation index NDVI calculated at the time of maximum development of the cover. Using the SPOT data, yield estimates, on a field scale, coulb be improved by combining the growth model Moicas and leaf area evolution obtained from the SPOT 4&5 images series. The hyper-spectral CASI data give a better estimate of the leaf area and fresh biomass than SPOT 4&5 data, with an estimate of the leaf nitrogen content which is, in phase of maturation, an indicator of sugar concentration. Tha ability to discriminate sugarcane fields according to their surface (full vegetation, cut or bare soil) has allowed to develop dynamic cartography of the sugarcane fields at the regional scale in near real time : the harvest and the replanting follow-ups.SAINT DENIS/REUNION-Droit Lettre (974112101) / SudocSudocFranceReunionFRR