By Pamela Ochungo
MAEASaM Kenya Postdoctoral Researcher, British Institute in Eastern Africa, Nairobi.
Nadia Khalaf
MAEASaM Ethiopia Postdoctoral Researcher, Institute of Arab and Islamic Studies, University of Exeter.
A key component of the MAEASaM project is the use of Remote Sensing techniques to assess and monitor the preservation, conditions, and susceptibility of threats to new and known heritage sites, and to predict future threats for heritage management planning. As authors of a new paper in the open access journal MPDI, Pamela Ochungo and Nadia Khalaf, two of MAEASaM’s Postdoctoral Researchers, illuminate the role of remote sensing in mapping pastoralist biocultural heritage in Eastern Africa.
The use of remote sensing technologies for the detection of archaeological sites and monuments and other forms of tangible cultural heritage has increased significantly in recent decades, including on the African continent. A common application has been the use of freely available satellite imagery, such as that provided via the Google Earth platform, to locate previously undocumented sites in remote areas that have not been the focus of systematic, pedestrian surveys. In contrast, there has been less use of Remote Sensing technologies to map and monitor examples of extant ‘biocultural heritage’, except where such heritage is located within designated protected areas as in national parks and cultural landscapes that are subject to more formalised management regimes.
In the Northern Kenya/Southern Ethiopia region, which is characterised by erratic rainfall, limited surface water, aridity and frequent droughts, sophisticated indigenous water management systems in the form of hand-dug wells have been developed to ensure equitable access to critical water resources. Well-digging has been attested among many pastoralist groups inhabiting areas of northern Kenya and southern Ethiopia. Examples include the ‘singing wells’ of the Kenyan Gabra, and the tula wells constructed by Borana communities in southern Ethiopia. By attributing socio-cultural and sacred values to water, pastoralists have managed to sustain access to water in this arid and semi-arid region for centuries. However, these systems are increasingly under threat from climate change and socio-economic development. This study therefore sought to apply Remote Sensing techniques for spatially explicit mapping of landscape structure around the wells, and to quantify the threats that face these wells through time.
Remote Sensing analysis was used to assess the scale, distribution, and intensity of these threats, by evaluating the land-use land-cover (LULC) and precipitation changes in this landscape and their association with, and impact on, the preservation of traditional wells. Multitemporal Landsat 5, 7 and 8 satellite imagery covering the period 1990 to 2020, analysed at a temporal resolution of 10 years, were classified using supervised classification via the Random Forest machine learning method to extract the following classes: bare land, grassland, shrub land, open forest, closed forest, croplands, settlement, and waterbodies. Change detection using Image Differencing methods were then applied to identify and quantify changes through time, following which landscape degradation indices were generated using the Shannon Diversity Index fragmentation index within a 15 km buffer of each well cluster.
The results indicated that land cover change was mostly driven by increasing anthropogenic changes with resultant reduction in land cover classes. Furthermore, increased fragmentation has occurred within most of the selected buffer distances of the well clusters. The main drivers of change that have directly, or indirectly impacted land degradation and the preservation of indigenous water management systems were identified through an analysis of land cover changes in the last 30 years, supporting insights from previous focused group discussions with communities in Kenya and Ethiopia. Our approach indicates that remote sensing methods can be used for the spatially explicit mapping of landscape structure around the wells, and ultimately towards assessment of the preservation status of the indigenous wells.
For more insights on this study, visit https://www.mdpi.com/2072-4292/14/2/314 and https://stories.council.science/unlocking-science-history-water-scarcity-africa/