Leveraging Google Earth Engine platform to characterize and map small seasonal wetlands in the semi-arid environments of South Africa
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Date
2021-07
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Although significant scientific research strides have been made in mapping the spatial extents and
ecohydrological dynamics of wetlands in semi-arid environments, the focus on small wetlands remains a challenge. This is due to the sensing characteristics of remote sensing platforms and lack of robust data processing
techniques. Advancements in data analytic tools, such as the introduction of Google Earth Engine (GEE) platform
provides unique opportunities for improved assessment of small and scattered wetlands. This study thus
assessed the capabilities of GEE cloud-computing platform in characterising small seasonal flooded wetlands,
using the new generation Sentinel 2 data from 2016 to 2020. Specifically, the study assessed the spectral separability of different land cover classes for two different wetlands detected, using Sentinel-2 multi-year composite
water and vegetation indices and to identify the most suitable GEE machine learning algorithm for accurately detecting and mapping semi-arid seasonal wetlands. This was achieved using the object based Random Forest (RF),
Support Vector Machine (SVM), Classification and Regression Tree (CART) and Naïve Bayes (NB) advanced algorithms in GEE. The results demonstrated the capabilities of using the GEE platform to characterize wetlands with
acceptable accuracy. All algorithms showed superiority, in mapping the two wetlands except for the NB method,
which had lowest overall classification accuracy. These findings underscore the relevance of the GEE platform,
Sentinel-2 data and advanced algorithms in characterizing small and seasonal semi-arid wetlands
Description
Keywords
Limpopo river basin, Object-based classification, Machine learning algorithm, Wetland mapping
Citation
Gxokwe, S. et al. (2021). Leveraging Google Earth Engine platform to characterize and map small seasonal wetlands in the semi-arid environments of South Africa