Evaluation of indicators for desertification risk assessment of Oleshky sands desertification based on Landsat data time series

Abstract

Earth's surface monitoring allows the assessment of the dynamics and mapping of desertification indicators and is currently one of the priority research regions in remote sensing. In addition to the fact that desertification is a serious global threat to economic, social and food security, the risks of desertification have also become relevant for southern Ukraine. In recent years, climate change has become more and more noticeable in Ukraine. As a result, the time frames of the seasons are blurred, the boundaries of natural zones are shifting, abnormal values of meteorological indicators are increasingly observed, and the intensity of natural disasters is increasing. Since southern Ukraine is most vulnerable to adverse climate and landscape changes, including desertification, the article considered long-term landscape changes on the right bank of the Dnieper River in the Kherson region, mainly represented by sandy massifs of the Oleshky region, which are called the Oleshky Sands. Arid landscapes, which include the vast majority of Oleshky, are especially vulnerable to degradation processes, so space monitoring this territory is an urgent task given the current global climate changes. Within the framework of the presented study, the long-term dynamics of several indicators of desertification within the sandy arenas of the Oleshkovsky sands were mapped. Based on a series of multispectral space images obtained by Landsat satellites for the period 1986-2020 was considered. Spectral ranges characterize the key biophysical aspects of arid landscapes: the degree of soil moisture, vegetation density and sand distribution. Regression analysis was used to illustrate the dynamics of each indicator, which showed a general increase in each indicator over the experimental period. Furthermore, we determined the relationship between the values of the rise in desertification indicators and landscape changes that occurred in the research region, the classification of several images for different years was also carried out, and spatial and quantitative changes in the distribution of land cover classes were characterized.