Assessment of Land Degradation in Semiarid Tanzania—Using Multiscale Remote Sensing Datasets to Support Sustainable Development Goal 15.3

Jonathan Reith,Gohar Ghazaryan,Francis Muthoni,Olena Dubovyk

doi:10.3390/rs13091754

Abstract

Monitoring land degradation (LD) to improve the measurement of the sustainable development goal (SDG) 15.3.1 indicator (“proportion of land that is degraded over a total land area”) is key to ensure a more sustainable future. Current frameworks rely on default medium-resolution remote sensing datasets available to assess LD and cannot identify subtle changes at the sub-national scale. This study is the first to adapt local datasets in interplay with high-resolution imagery to monitor the extent of LD in the semiarid Kiteto and Kongwa (KK) districts of Tanzania from 2000–2019. It incorporates freely available datasets such as Landsat time series and customized land cover and uses open-source software and cloud-computing. Further, we compared our results of the LD assessment based on the adopted high-resolution data and methodology (AM) with the default medium-resolution data and methodology (DM) suggested by the United Nations Convention to Combat Desertification. According to AM, 16% of the area in KK districts was degraded during 2000–2015, whereas DM revealed total LD on 70% of the area. Furthermore, based on the AM, overall, 27% of the land was degraded from 2000–2019. To achieve LD neutrality until 2030, spatial planning should focus on hotspot areas and implement sustainable land management practices based on these fine resolution results.

Highlights

Land degradation (LD) is defined as the “continuous reduction or loss of the productivity of the land due to a combination of natural and anthropogenic causes” [1]
The patterns of each sub-indicator based on data and methodology (DM) and AM are described starting with the baseline period (BP) from 200 to 2015 for both DM and AM
According to the DM based on the medium-resolution 300 m land cover (LC) maps, over 99% of the study area remained stable in the BP (2000–2015) (Table A1)

Summary

Introduction

Land degradation (LD) is defined as the “continuous reduction or loss of the productivity of the land due to a combination of natural and anthropogenic causes” [1]. It is a global problem and affects people, their livelihoods and nature. Studies suggest that up to 3.2 billion people live and depend on degraded lands [2] and that approximately a quarter of the world’s lands are affected by LD [3,4]. Lost ecosystem services due to land use and land cover (LULC) change and LD account for up to USD 10.5 trillion loss per year, which is about a sixth of the world’s gross domestic product (GDP) [7]. Biodiversity is declining globally, with tremendous losses in sub-Saharan Africa because of LD [6]

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Discussion

Conclusion