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

Accueil du site → Master → Pays Bas → Analysis of NDVI time series to detect bush encroachment : a case study in Cadiz (Spain) assessing three different methods on the basis of minimum NDVI.

International Institute for Geo-Information Science and Earth Observation (ITC) 2013

Analysis of NDVI time series to detect bush encroachment : a case study in Cadiz (Spain) assessing three different methods on the basis of minimum NDVI.

Estupiñan-Suarez, L.M. 

Titre : Analysis of NDVI time series to detect bush encroachment : a case study in Cadiz (Spain) assessing three different methods on the basis of minimum NDVI.

Auteur : Estupiñan-Suarez, L.M. 

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 2013

Résumé
Encroachment is an ecological succession process where perennial plants such as bushes and trees replace annual vegetation. In general, bushes establishment increases and the canopy tends to close. This process leads to gradual changes in land cover. Until now, bush encroachment detection using remote sensing has required high spatial resolution. This study aimed to investigate three different methods which use moderate spati al re sol uti on ti me se ri e s of MODIS-NDV I 250m from 2001 to 2012. It pursued to differentiate between bushes (evergreen perennial cover) and annual vegetation cover. For that purpose, the assessed dataset was constrained to the three NDVI composites that hold the lowest NDVI values (min.NDVI) for each year. The three evaluated methods were : (a) CoverCAM, (b) Cover Fraction and (c) Quantile Linear Regression (QuantReg). All of them were based on min.NDVI time series. The study area was the province of Cadiz (Spain) where land degradation and land abandonment has increased, two of the major causes of encroachment. The findings revealed that the potential use of minimum NDVI to detect bush encroachment varies among methods. The method wi th highest accuracy is QuantReg (PCC=0.77) and its bush encroachment detection is 0.82 (Sensitivity). CoverCAM and Cover-Fraction showed a low power of detection. It is concluded that QuantReg is a robust approach for bush encroachment detection and has potential application in surveying large areas.

Version intégrale (ITC)

Page publiée le 31 janvier 2018