Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : The impact of Leaf Area Index on rainfall interception and the potential to estimate it using Sentinel-1 observations

Auteur : Duan, T. (Ting)

Etablissement de soutenance : University of Twente International Institute for Geo-Information Science and Earth Observation (ITC)

Grade : Master of Science in Geo-Information Science and Earth Observation 2017

Résumé
Rainfall interception accounts for a significant part of the water cycle in both forest and agricultural ecosystems. However, most researches focused on the forest interception and few focused on the crop interception. Corn as a typical seasonally dynamic crop can intercept a substantial amount of water at fully-grown stage. Knowing the amount of interception will improve hydrological models and enable water managers to make better informed decisions , for example regarding flood warnings . In this study, rainfall, throughfall and vegetation parameters (including leaf area index (LAI) , plant height) are measured once a week from May 2016 to November 2016 in the Twente region in the east of the Netherlands . The temporal and spatial variations of these parameter s were analysed at field scale . The result showed that the interception of corn plants at its fully- grown stage can reach 90% of total rainfall. The rainfall interception is positively correlated with LAI. The temporal and spatial variations of Synthetic Aperture Radar (SAR) Sentinel- 1 C- band backscatter were also analysed at field scale. The correlation of the backscatter with LAI was investigated. However, the correlation of Sentinel- 1 backscatter and LAI at field scale is low, R 2 is no more than 0.4. Sentinel- 1 SAR images enable to monitor vegetation growth stage at a regional scale. Among the , and ratio, is most sensitive to temporal variation of LAI at field scale . The polarization ratio has a lower sensivity to vegetation growth stage. is also not very sensitive to vegetation growth stage, but it can be used together with to distinguish vegetated and non- vegetated areas. Very high interception ratios observed at corn fully- grown stage, it is so important to consider and monitor this component in agricultural areas . The interception is positively correlated with LAI, but it isn ’t available to estimate the interception using LAI. Sentinel- 1 SAR image s enable to monitor vegetation growth stage at a regional scale. But the correlation of Sentinel- 1 backscatter and LAI is low, so it isn’t possible for Sentinel- 1 to estimate the exact value of LAI.

Version intégrale (ITC)