Authors: Elia Axinia Machado*, Lehman College, CUNY, Andrew Simons, Fordham University, NY
Topics: Human-Environment Geography, Hazards and Vulnerability, Remote Sensing
Keywords: NDVI, pastoralism, Ethiopia, Vulnerability, land use change
Session Type: Virtual Paper
Start / End Time: 3:05 PM / 4:20 PM
Room: Virtual 9
Presentation File: No File Uploaded
Changes in land tenure systems, land use-cover change (LUCC), and increased climate variability are among the major drivers of pastoralism vulnerability. However, the research about how these factors interplay and the trends of relevant climatic and vegetation variables remains inconclusive.
This study offers a more targeted approach by focusing specifically on the grazing lands used by pastoralists. We calculate interannual NDVI trends (AHVRR GIMMS NDVI3g, 1982-2014) using non-parametric methods and integrate the results with a LUCC analysis (2003-2008) in these areas. Polygons of these areas were delineated by pastoralists during a participatory process in 2005.
Results of the trend analysis indicate a decrease of NDVI in the grazing areas, with an average Theil Sen slope of -0.0043 over the study period. About 30% of the pixels in the study area have a significant trend (95% confidence). Overall, these areas are associated with a stepper decrease in NDVI (average slope -0.012 over the study period). However, they also include polygons with significant positive (0.070) and negative (-0.035) average slopes during that time. Grazing areas characterized by decreasing NDVI values are mostly associated with the expansion of settlements, whereas none of the areas with positive NDVI slopes included settlements between 2003-2008. These land use and cover transitions only represent a portion of the longer NDVI data record though.
Our research resonates with previous studies describing negative NDVI and rainfall trends in this region, but also highlights the challenges of informing vulnerability assessments of pastoralism from a remote sensing and GIS perspective.