Assessing vegetation degradation using high-resolution satellites in the region of Lake Manyara

Abstract

This thesis aims to assess vegetation degradation in the region of Lake Manyara in Northern Tanzania over the years 2017 until 2021. Multiple studies concluded that the LULC is changing around Lake Manyara over the past years. In some cases, this is due to humans, while in other cases it is suggested that it is due to vegetation degradation. Previous studies showed high vegetation resilience and no signs of vegetation degradation, yet the Maasai observed a change in vegetation. Vegetation changes are observed in similar areas, these changes are changes from high-nutritious grasses to lownutritious grasses and bush encroachment. The assessment is done with the high-resolution satellites, Sentinel-2 and PlanetScope, with soil moisture data from SMAP and precipitation data from CHIRPS 2.0. The indices for the assessment are NDVI, GCC, MBI and NDWI. This thesis concluded that precipitation and infiltration were not simultaneously, infiltration occurred later. Vegetation did not start growing simultaneously with precipitation, but with infiltration in the subsurface. The lack of infiltration could be due to that crusting is affecting the vegetation in the area. Crusting results in less infiltration and less growth of grasses, while shrubs and trees are less affected by crusting. This result is in line with bush encroachment and is a good indication that vegetation degradation might occur in the grassland and savannah areas around Lake Manyara. Vegetation resilience is still high, although vegetation does not start to grow when the precipitation starts. Vegetation starts to grow when water infiltrates the subsurface.