Monitoring the Spatiotemporal Dynamics of Aeolian Desertification Using Google Earth Engine

Northern China has been long threatened by aeolian desertification. In recent years, all levels of the Chinese government have performed a series of ecological protection and sand control projects. To grasp the implementation effects of these projects and adjust policies in time, it is necessary to understand the process of aeolian desertification quickly and accurately. Remote sensing technologies play an irreplaceable role in aeolian desertification monitoring. In this study, the Zhenglan Banner, which is in the hinterland of the Hunshandake Sandy Land, was considered as the research area. Based on unmanned aerial vehicle (UAV) images, ground survey data, and Landsat images called in Google Earth Engine (GEE), the aeolian desertified land (ADL) in 2000, 2004, 2010, 2015, and 2019 was extracted using spectral mixture analysis. A desertification index (DI) was constructed to evaluate the spatial and temporal dynamics of the ADL in the Zhenglan Banner. Finally, a residual analysis explored the driving forces of aeolian desertification. The results showed that (1) the ADL area in the Zhenglan Banner has been trending downwards over the past 20 years but rebounded from 2004 to 2010; (2) over the past 20 years, the area of slightly, moderately, and severely desertified land has decreased at annual rates of 0.4%, 2.7%, and 3.4%, respectively; (3) human activities had significantly positive and negative impacts on the aeolian desertification trend for 20.0% and 21.0% of the study area, respectively, but not for the rest. This paper explored new techniques for rapid aeolian desertification monitoring and is of great significance for controlling and managing aeolian desertification in this region.

(Landscape monitoring and assessment in Sirte (Libya: مراقبة وتقييم المناظر الطبيعية في سِرْت (ليبيا)

Changing ecological and socio-economic circumstances make land degradation a major concern in Mediterranean area. The objectives were to examine the spatiotemporal patterns of land use/cover dynamics and quantify the rate and direction of these dynamics in Sirte, Libya. Remotely sensed data including Land cover (MCD12Q1), MODIS NDVI (MOD13A3) for 2001-2014 and TRIMM precipitation data for 2001-2014 were interpreted. The results showed no significant trend; but a decrease in sand dunes and semi-fixed sand dunes with a change rate of 15.66 and 116.37 km² year−1, respectively, in the meantime the vegetation cover has increased with an increasing rate of 112 km² year−1. The results also showed that the high-, and medium degree desertification area has decreased by about (25 %) but showed no significant changes. However, land desertification monitoring and Assessment using remote sensing still needs to be continued and also refined for the purpose of long-term monitoring and the management of fragile environments in the area.

Responses of aeolian desertification to a range of climate scenarios in China

Aeolian desertification plays an important role in earth-system processes and ecosystems, and has the potential to greatly impact on global food production. The occurrence of aeolian desertification has traditionally been attributed to increases in wind velocity and temperature, and decreases in precipitation. In this study, by integrating the aeolian desertification monitoring data and climate and vegetation indices, we found that although aeolian desertification is influenced by complex climate patterns and human activities, increases in precipitation and temperature, and decreases in wind speed, may also trigger aeolian desertification in China. Our results show that, even when modern technical approaches are used, different approaches to desertification need to be applied to account for regional differences. These results have important implications for future policy decisions on how best to combat desertification.