Zhengissova et al. (2025) Analysis of spatio-temporal changes of surface water within the Semipalatinsk test site based on the Google Earth Engine platform

Identification

• Journal: BULLETIN of the L N Gumilyov Eurasian National University Chemistry Geography Series
• Year: 2025
• Date: 2025-12-24
• Authors: N. Zhengissova, Omirzhan Taukebayev, K. Temirbayeva, Aizhan Assylbekova
• DOI: 10.32523/2616-6771-2025-153-4-106-121

Research Groups

• Space Technologies, and Remote Sensing Center, Al-Farabi Kazakh National University, Almaty, Kazakhstan
• Department of Cartography and Geoinformatics, Al-Farabi Kazakh National University, Almaty, Kazakhstan
• Cluster of Engineering and High Technologies, Al-Farabi Kazakh National University, Almaty, Kazakhstan

Short Summary

This study analyzed the spatio-temporal dynamics of surface water bodies within the Semipalatinsk Test Site from 1996 to 2024 using remote sensing data on the Google Earth Engine platform, revealing a strong dependence of water extent on winter climatic conditions and a prevalence of temporary water bodies.

Objective

• To analyze the spatio-temporal changes of surface water bodies within the Semipalatinsk Test Site (STS) using satellite data and the analytical capabilities of the Google Earth Engine (GEE) platform.
• To develop a map of surface water and irrigation systems to support landscape planning of the area.

Study Configuration

• Spatial Scale: Semipalatinsk Test Site (STS), eastern Kazakhstan, covering approximately 18300 square kilometers.
• Temporal Scale: 1996–2024, with specific temporal snapshots in 1996, 2000, 2010, 2012, 2020, and 2024. Analysis focused on the vegetation period (May–September).

Methodology and Data

• Models used:
  • Google Earth Engine (GEE) platform for data processing and analysis.
  • Modified Normalized Difference Water Index (MNDWI) for water surface extraction.
  • Water Frequency (WF) calculation for water body persistence classification.
  • Dynamic coefficient K for quantifying changes in surface water extent.
• Data sources:
  • Satellite imagery: Landsat (TM, ETM+, OLI) and Sentinel-2 MSI.
  • Climatic data: ERA5-Land reanalysis (mean winter air temperature, total snowfall).
  • Digital Elevation Model (DEM): SRTM (30 meter spatial resolution).
  • Reference samples for validation: Sentinel-2 and Google Earth imagery.

Main Results

• The total area of water surfaces within the STS varied significantly, from a minimum of 4512.9 hectares (0.24% of the total area) in 1996 and 2012 to a maximum of 14993.9 hectares (0.81%) in 2010, representing a nearly threefold fluctuation.
• The largest extents of water surfaces were observed in years characterized by cold and snowy winters (2000 and 2010), while the smallest extents occurred during warm and low-snow periods (1996, 2012, and 2024).
• Temporary and seasonal water bodies prevail within the test site, with their share exceeding 60% of the total water area, reflecting the instability of the hydrological regime and its strong dependence on climatic variability. Permanent water bodies constitute approximately 30–35%.
• Water bodies are primarily concentrated in the valleys of the Shagan and Ashchysu rivers and in closed depressions in the eastern and southeastern parts of the test site.
• A clear negative correlation was established between mean winter air temperature and the area of water surfaces, with winter snowfall being a key factor in shaping spring runoff and floodwater recharge. Summer precipitation showed a much weaker influence.
• The MNDWI-based classification demonstrated high reliability with an overall accuracy of 94.0%, a producer's accuracy of 75.0% for the "water" class, and a user's accuracy of 85.7%.

Contributions

• Provided a comprehensive spatio-temporal analysis of surface water dynamics in the Semipalatinsk Test Site over a nearly three-decade period (1996-2024) using the Google Earth Engine platform.
• Quantified the strong climatic dependence of the region's hydrological regime, specifically highlighting the critical role of winter air temperature and snowfall in determining water body extent and persistence.
• Demonstrated the effectiveness and potential of modern remote sensing platforms like Google Earth Engine and the MNDWI index for water resource management and dynamic assessment in arid, anthropogenically impacted territories.
• Offered practical value for environmental monitoring, landscape planning, and assessing the impacts of climate change on degraded lands, particularly for potential agricultural development in the former test site areas.
• Emphasized the unique combination of natural and technogenic factors influencing water bodies in the STS, making it a valuable model area for studying the consequences of climatic and anthropogenic changes.

Funding

• Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan, grant number AP19579264.

Citation

@article{Zhengissova2025Analysis,
  author = {Zhengissova, N. and Taukebayev, Omirzhan and Temirbayeva, K. and Assylbekova, Aizhan},
  title = {Analysis of spatio-temporal changes of surface water within the Semipalatinsk test site based on the Google Earth Engine platform},
  journal = {BULLETIN of the L N Gumilyov Eurasian National University Chemistry Geography Series},
  year = {2025},
  doi = {10.32523/2616-6771-2025-153-4-106-121},
  url = {https://doi.org/10.32523/2616-6771-2025-153-4-106-121}
}