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Ondokuz Mayıs Üniversitesi (2019)

Mapping evapotranspiration by using remote sensing techniques in Senegal Richard Toll zone

BALDE Hamadou

Titre : Mapping evapotranspiration by using remote sensing techniques in Senegal Richard Toll zone

Senegal Richard Toll bölgesinde uzaktan algılama teknikleri kullanılarak evapotranspirasyonun haritalanması

Auteur : BALDE Hamadou

Université de soutenance : Ondokuz Mayıs Üniversitesi

Grade : Master Thesis 2019

Résumé
Estimating and mapping crop Evapotranspiration (ETa) within arid and semi-arid regions such as Senegal where the water scarcity is the most pronounced is of importance. Mapping ET at fields scale can allow supplying the right amount of water at a right time during the crop growth season and improving crop yields indeed. In this study, the availabilities of mapping ETa using the Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) model and remote sensing techniques over irrigated and rainfed fields in Senegal was investigated. The investigation was carried out during 2016 and 2017 growing seasons in Richard Toll (Senegal). Within these agricultural areas, sugar cane and rice are the most grown crops. For mapping ETa at fields scale, a total of 29 Landsat 8 satellite images and daily climate data were used. The satellite data were processed and the Normalized Difference Vegetation Index (NDVI) and ETa were computed and mapped. The obtained NDVI and ETa maps have successfully displayed the sowing, growing and harvesting periods of rice and sugar cane crops at the field scale. Overall, the average NDVI values for rice crop in 2016 varied from 0.1 to 0.6 and from 0.36 to 0.58 for sugar cane, while in 2017, NDVI values ranged from 0.18 to 0.61 and from 0.36 to 0.62 for rice and sugar cane, respectively. On the other hand, for the rice crop, the daily ETa values ranged from 3.40 to 12.0 mm.day-1, and for the sugar cane ET values were within the range between 3.20 to 8.50 mm. day-1 in 2016, whereas in 2017 for rice the ETa varied from 2.0 ile 8.0 mm. day-1 and for sugar cane ETa was within the range betwen 3.0 and 7.40 mm. day-1. The low NDVI and ETa values indicated either uncultivated plots, bare soils, water stressed or dry fields, while the high values denoted well-watered fields and hence assimilated to high NDVI values. As a result, these findings significantly highlighted the availability of mapping ETa and using remotely sensing techniques in Richard Toll.

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