Quantitative Soil Wind Erosion Potential Mapping for Central Asia Using the Google Earth Engine Platform

Windbreak and sand fixation service flow simulation in the terminal lake basin of inland rivers in arid regions: A case study of the Aral Sea basin

Research on windbreak and sand fixation (WSF) services aids in soil conservation, and ecological protection. Over the past 50 years, the Aral Sea's shrinkage has intensified wind erosion, leading to significant sand and dust emissions in Central Asia (CA). This study uses the Revised wind erosion equation (RWEQ) model and the hybrid single particle Lagrangian integrated trajectory model (HYSPLIT) model to simulate the spatiotemporal variation pattern of WSF services in the Aral Sea basin (ASB). From the perspective of sand and dust transmission paths, the flow trajectory and benefit areas of WSF services are identified, the spatiotemporal correlation between the WSF service supply areas and benefit areas is established, and the potential impact of WSF services on beneficiary areas is quantitatively assessed. The results show the amount of wind erosion and the amount of WSF in the ASB from 2000 to 2019 showed a fluctuating trend of "first increasing and then decreasing". In terms of spatial distribution, areas with large amounts of WSF are mainly distributed in the lower reaches of the Syr Darya River and the sand dunes in the northwest of the Kizilkum Desert. WSF services mainly flow through the Kizilkum Desert, Karakum Desert, Moyinkum Desert, Kazakh Hills, and the Junggar Basin and Tarim Basin in China. Generally, it flows to the northeast and southwest. In the past 20 years, the largest areas benefiting from the flow of WSF services are mainly distributed in Uzbekistan, Kyrgyzstan, and Tajikistan. The trajectory distribution frequency shows a decreasing trend from the center to the periphery. The grassland areas constituted the largest beneficiary areas in the ASB of CA, with both the beneficiary population and real GDP exhibiting an upward trend. This study holds significant importance for enhancing the management of ecosystem services in sandy regions and for establishing ecological compensation mechanisms.

Indicator-based assessments of the coupling coordination degree and correlations of water-energy-food-ecology nexus in Uzbekistan

Grappling with the global ecological concern of the Aral Sea disaster, Uzbekistan exemplifies the urgent necessity of unravelling and addressing the complex Water-Energy-Food-Ecology (WEFE) nexus conflicts in arid regions, a critical task yet largely uncharted. Through the strategic process of 'Indicator Articulation - Weight Calibration - Nexus Coordination Quantification - Correlational Analysis', this work has developed a tailored framework that integrates a novel, context-specific indicator system, enabling an illumination of the intricate dynamics within the WEFE nexus in arid regions. During 2000-2018, the WEFE Nexus in Uzbekistan showed low-level coordination, indicating systemic imbalances. The Aral Sea crisis was the central disruptor, resulting in a moderately disordered ecological subsystem. Concurrently, disorder was observed in water resources, signaling inadequate management and potential overutilization. Furthermore, Coordination for energy and food were barely coordinated and under primary coordination respectively, underlining critical challenges in energy efficiency and food security. Over the last two decades, the WEFE Nexus has evolved towards a tighter interlinkage, yet the stability of this coupling coordination has experienced increased fluctuations, indicating that Uzbekistan's policies in the WEFE subsystems have been less stable in the last two decades and are in need of further adjustment and improvement. To address the challenges, we recommend a comprehensive approach that integrates technological, infrastructure, and policy solutions is needed. Specifically, promoting water-saving irrigation technology, renewing and maintaining outdated energy facilities, and raising public awareness of ecological protection are part of the essential measures. Furthermore, alleviating the contradiction between economic growth and ecological conservation remains a major challenge. Collectively, our constructed WEFE Nexus framework, with its extendable and context-specific indicators, holds significant potential for broad application in the analysis of multi-sectoral sustainability, particularly within arid regions globally, and forms a solid foundation for the formulation of effective, targeted policies and sustainable development strategies.

Using Open Foris Collect Earth in Kyrgyzstan to support greenhouse gas inventory in the land use, land use change, and forestry sector

The Kyrgyz Republic (Kyrgyzstan) is one of the countries most vulnerable to the adverse effects of climate change in Central Asia. The land use, land use change, and forestry (LULUCF) sector is critical in climate change mitigation in Kyrgyzstan and is integral to national greenhouse gas (GHG) inventories. However, consistent, complete, and updated activity data is required for the LULUCF sector to develop a transparent GHG inventory. Collect Earth (CE), developed by the Food and Agriculture Organization of the United Nations (FAO), is a free, user-friendly, and open-source tool for collecting activity data for the LULUCF sector. CE assists countries in developing GHG inventories by providing consistent and complete land representation. This article reports an estimate of land use and land-use change dynamics in Kyrgyzstan, based on analyzing 13,414 1-hectare (ha) sampling units through an augmented visual interpretation approach using satellite imagery at the very high spatial and temporal resolution available through the Google Earth platform. The results show that in 2019, forests covered 1.36 million ha or 6.83% of the total land with a 6.23% uncertainty. This estimate was 5 to 16% higher than previous estimates, detecting an additional 63,024 to 188,164 ha of forestland that had not been reported previously. The new estimates suggest an average increase of 10.4% in the current forestlands of Kyrgyzstan.

Spatiotemporal variations and driving factors for potential wind erosion on the Mongolian Plateau

Wind erosion can cause desertification and sandstorms in arid and semiarid areas. However, quantitative studies of the dynamic changes in wind erosion over long time periods are relatively rare, and this knowledge gap hinders our understanding of desertification under the conditions of a changing climate. Here, we selected the Mongolian Plateau as the study area. Using the revised wind erosion equation (RWEQ) model, we assessed the spatial and temporal dynamics of wind erosion on the Mongolian Plateau from 1982 to 2018. Our results showed that the wind erosion intensity on the Mongolian Plateau increased from northeast to southwest. The annual mean wind erosion modulus was 46.5 t·ha^-1 in 1982-2008, with a significant decline at a rate of -5.1 t·ha^-1·10 yr^-1. The intensity of wind erosion was the strongest in spring, followed by autumn and summer, and was weakest in winter. During 1982-2018, wind erosion showed a significant decreasing trend in all seasons except winter. The wind erosion contribution of spring to the total annual wind erosion significantly increased, while that of summer significantly decreased. These results can help decision-makers identify high-risk areas of soil erosion on the Mongolian Plateau and take effective measures to adapt to climate change.

High-resolution, spatially resolved quantification of wind erosion rates based on UAV images (case study: Sistan region, southeastern Iran)

Estimating the quantitative distribution of wind erosion rates is one of the most important requirements for managing affected environments and optimizing locations to control wind erosion. This study develops high-resolution maps for wind erosion with unmanned aerial vehicles or UAV images in the Sistan region-an area in southeastern Iran with severe wind erosion. Aerial imaging by UAV was done during period of erosive winds. Changes in the amount of wind erosion were measured for 7 months. Digital elevation models or DEM with a spatial resolution of 6 mm, orthophoto mosaic images with a resolution of 3 mm, were prepared before and after the erosion event. Three erosive facies consisting of surface, edge, and blowout were identified. The amount of erosion in different geomorphological landscapes or facies was measured according to differences of DEMs (DOD). The effect of physical factors of the geomorphological landscapes on wind erosion was investigated by calculating the correlation between the erosion, roughness, and slope in the geomorphological landscapes. The results showed that the highest and lowest mean of eroded soil were 22 mm and 4 mm in the blowout and surface facies, respectively. The average rate of wind erosion was 201 t/ha during the study period, which indicates the high intensity of wind erosion in the Sistan plain. Overall, UAV-as an aerial imaging technique collecting ground data-can be a helpful tool in the aeolian geomorphology especially for collecting data for measuring the rate of soil erosion by the wind in the aeolian landscapes located in remote regions.

Field scale spatio-temporal variability of wind erosion transport capacity and soil loss at Urmia Lake

Urmia Lake has been known as the second hypersaline lake in the world, with the surface area of approximately 5200 km². With decreasing the water input of the lake due to anthropogenic activities, the susceptible areas to wind erosion and dust emission were extended during the last decades. The present study attempted to measure wind erosion on the edge of Urmia Lake for three years since 2017. In order to provide a quantitative understanding of wind erosion parameters in the dried up Urmia Lake area, and to prioritize different areas in terms of wind erosion intensity, it was necessary to establish wind erosion measurement and monitoring stations in different areas of dried up shores. Wind erosion measurement and monitoring stations were established in six erodible areas such as Salmas, Jabal Kandi, Soporghan, Miandoab, Khaselou and Ajabshir. Wind erosion parameters such as transport capacity and soil loss in the dried margin of Urmia Lake were determined. For this purpose, BSNE traps were used in the layout of two circles having an identical center. After each wind erosion event, sediment traps were emptied and weighted; then, the vertical and horizontal distribution of the particulate matters was calculated. Comparison of the values of maximum transport capacity-f_max (kg/m.yr) and soil loss- SL (ton/ha.yr) of aeolian particulate in 2017 showed that the two main centers of wind erosion on the edge of Urmia Lake were Ajabshir and Jabal Kandi. The stations of Khaselou, Salmas, Soporghan and Mianduab were in the declined ranking. Results showed that the transfer capacity values were 351.97 and 297.30 kg/m/year and soil losses were 18.04 and 35.4 ton/ha/year, respectively, for the stations with high wind erosion potential, i.e., Ajab Shir and Jabal Kandi, in 2017. Furthermore, these values were significantly reduced for the mentioned stations in 2019, so that the values obtained from the transfer capacity reached 54.93 and 40.39 kg/m/year and soil losses reached 3.70 and 2.43 ton/ha. Investigating the results of transport capacity and soil loss showed the decreasing trend in wind erosion rate due to the increasing water level of the lake as well as biological and engineering conservation practices (non-live windbreaks) from 2017 to 2019.

Insights into Variations and Potential Long-Range Transport of Atmospheric Aerosols from the Aral Sea Basin in Central Asia

The dramatic shrinkage of the Aral Sea in the past decades has inevitably led to an environmental calamity. Existing knowledge on the variations and potential transport of atmospheric aerosols from the Aral Sea Basin (ASB) is limited. To bridge this knowledge gap, this study tried to identify the variations and long-range transport of atmospheric aerosols from the ASB in recent years. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data were used to gain new insight into the types, variation and long-range transport of atmospheric aerosols from the ASB. The results showed five types of tropospheric aerosols and one type of stratospheric aerosol were observed over the ASB. Polluted dust and dust were the dominant subtypes through the year. Sulfate/other was the only stratospheric aerosol detected. The occurrence frequency of aerosols over the ASB showed obvious seasonal variation. Maximum occurrence frequency of dust appeared in spring (MAM) and that of polluted dust peaked in summer (JJA). The monthly occurrence frequency of dust and polluted dust exhibited unimodal distribution. Polluted dust and dust were distributed over wide ranges from 1 km to 5 km vertically. The multi-year average thickness of polluted dust and dust layers was around 1.3 km. Their potential long-range transport in different directions mainly impacts Uzbekistan, Turkmenistan, Kazakhstan and eastern Iran, and may reach as far as the Caucasus region, part of China, Mongolia and Russia. Combining aerosol lidar, atmospheric climate models and geochemical methods is strongly suggested to gain clarity on the variations and long-range transport of atmospheric aerosols from the Aral Sea Basin.

Land Degradation Assessment with Earth Observation

For decades now, land degradation has been identified as one of the most pressing problems facing the planet [...]

Assessment of environmentally sensitive areas to desertification in the Blue Nile Basin driven by the MEDALUS-GEE framework

Assessing environmentally sensitive areas (ESA) to desertification and understanding their primary drivers are necessary for applying targeted management practices to combat land degradation at the basin scale. We have developed the MEditerranean Desertification And Land Use framework in the Google Earth Engine cloud platform (MEDALUS-GEE) to map and assess the ESA index at 300 m grids in the Blue Nile Basin (BNB). The ESA index was derived from elaborating 19 key indicators representing soil, climate, vegetation, and management through the geometric mean of their sensitivity scores. The results showed that 43.4%, 28.8%, and 70.4% of the entire BNB, Upper BNB, and Lower BNB, respectively, are highly susceptible to desertification, indicating appropriate land and water management measures should be urgently implemented. Our findings also showed that the main land degradation drivers are moderate to intensive cultivation across the BNB, high slope gradient and water erosion in the Upper BNB, and low soil organic matter and vegetation cover in the Lower BNB. The study presented an integrated monitoring and assessment framework for understanding desertification processes to help achieve land-related sustainable development goals.

Mapping Blue and Red Color-Coated Steel Sheet Roof Buildings over China Using Sentinel-2A/B MSIL2A Images

Accurate and efficiently updated information on color-coated steel sheet (CCSS) roof materials in urban areas is of great significance for understanding the potential impact, challenges, and issues of these materials on urban sustainable development, human health, and the environment. Thanks to the development of Earth observation technologies, remote sensing (RS) provides abundant data to identify and map CCSS materials with different colors in urban areas. However, existing studies are still quite challenging with regards to the data collection and processing costs, particularly in wide geographical areas. Combining free access high-resolution RS data and a cloud computing platform, i.e., Sentinel-2A/B data sets and Google Earth Engine (GEE), this study aims at CCSS material identification and mapping. Specifically, six novel spectral indexes that use Sentinel-2A/B MSIL2A data are proposed for blue and red CCSS material identification, namely the normalized difference blue building index (NDBBI), the normalized difference red building index NDRBI, the enhanced blue building index (EBBI), the enhanced red building index (ERBI), the logical blue building index (LBBI) and the logical red building index (LRBI). These indexes are qualitatively and quantitatively evaluated on a very large number of urban sites all over the P.R. China and compared with the state-of-the-art redness and blueness indexes (RI and BI, respectively). The results demonstrate that the proposed indexes, specifically the LRBI and LBBI, are highly effective in visual evaluation, clearly detecting and discriminating blue and red CCSS covers from other urban materials. Results show that urban areas from the northern parts of P.R. China have larger proportions of blue and red CCSS materials, and areas of blue and red CCSS material buildings are positively correlated with population and urban size at the provincial level across China.

Projections of desertification trends in Central Asia under global warming scenarios

Central Asia (CA) is a core area of global desertification, but the effect of the intensifying "global greening" policy on the desertification process under global warming scenarios in CA remains unclear. Based on multi-source remote sensing data and Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) 2b climate data, this study investigated desertification in CA using actual evapotranspiration (ETa), temperature and precipitation as driving factors. Coupling with the CA-Markov model, the inversion method of desertification was improved, and the evolution normal form of desertification in CA was proposed. Finally, spatio-temporal variations of desertification in CA were quantified. The results indicate that temperature, precipitation, and normalized difference vegetation index (NDVI) in CA increased during the historical period (1980-2015), with sudden changes in 1994. In contrast, although ETa exhibited fluctuating increases (7.41 mm/10 yr) during this period, no sudden changes were observed in 1994. In the future (2006-2099), the climate of CA will become warmer and wetter. With reference to 1980-2005, precipitation under global warming of 2.0 °C (GW2.0) will be higher than that under global warming of 1.5 °C (GW1.5) by 10.3 mm, and ETa will increase by 20.88 mm and 27.54 mm under GW1.5 and GW2.0, respectively. Although the area of desert lands has decreased (5.94 × 10⁴ km²/10 yr), the area of potential desert lands has increased (0.17 × 10⁴ km²/10 yr). With global warming, this situation will continue to intensify, mainly in Xinjiang of China, and Kazakhstan. The Aral Sea plays an important role in the desertification of CA. The potential increase in desert land under GW2.0 is equivalent to the current water area of the Aral Sea. The findings could provide policy support for combating desertification in CA and promoting the achievement of the Sustainable Development Goals.

Long-Term Impact of Wind Erosion on the Particle Size Distribution of Soils in the Eastern Part of the European Union

Wind erosion is the leading cause of soil degradation and air pollution in many regions of the world. As wind erosion is controlled by climatic factors, research on this phenomenon is urgently needed in soil and land management in order to better adapt to climate change. In this paper, the impact of wind erosion on the soil surface in relation to particle size distribution was investigated. Changes in percentage of sand, silt and clay fractions based on historical KPP data (1961–1970), LUCAS data base (2009), and field measurements (2016) were analysed in five cadastral areas impacted by wind erosion (Záhorie Lowlands, Slovakia). With the use of GIS tools, models of spatial distribution of sand, silt, clay and erodible fraction (EF) content were developed based on those measurements. Our findings proved that soil texture change driven by wind erosion could happen relatively quickly, and a significant proportion of soil fine particles may be carried away within a few years. The results indicate that the soil surface became much rougher over the period of more than 50 years, but also that the accumulation of fraction of the silt particles occurred in most of the areas affected by the erosive effect.