Meng et al. (2025) Soil salinity patterns reveal changes in the water cycle of inland river basins in arid zones

Identification

• Journal: Hydrology and earth system sciences
• Year: 2025
• Date: 2025-10-09
• Authors: Gaojia Meng, Guofeng Zhu, Yinying Jiao, Dongdong Qiu, Yuhao Wang, Siyu Lu, Rui Li, Jiawei Liu, Longhu Chen, Qinqin Wang, Enwei Huang, Wentong Li
• DOI: 10.5194/hess-29-5049-2025

Research Groups

• College of Geography and Environmental Science, Northwest Normal University, Lanzhou, China
• Lanzhou Sub-Center, Remote Sensing Application Center, Ministry of Agriculture, Lanzhou, China
• Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou, China
• Key Laboratory of Resource Environment and Sustainable Development of Oasis, Lanzhou, China

Short Summary

This study quantitatively analyzed soil salinization changes in the Shiyang River basin of Northwest China from 2002 to 2022 using remote sensing, revealing that human activities, particularly water conservancy projects and agricultural irrigation, are the primary drivers of intensifying salinization patterns.

Objective

• To quantitatively analyze the degree of salinization in the Shiyang River basin and reveal its spatial and temporal distribution characteristics.
• To analyze the impacts of water cycle changes on salinization, specifically focusing on water conservancy projects and agricultural irrigation.

Study Configuration

• Spatial Scale: Shiyang River basin, Northwest China, encompassing the Southern Qilian Mountains, Central Corridor Plain, and Northern Hills and Oasis–Desert Transition Zone.
• Temporal Scale: 2002 to 2022, with specific analysis nodes in 2002, 2007, 2012, 2017, and 2022.

Methodology and Data

• Models used: Support Vector Machine (SVM) algorithm for supervised classification, Normalized Difference Salinity Index (NDSI).
• Data sources:
  • Remote Sensing: Landsat-5, Landsat-7, Landsat-8, and Landsat-9 satellite data (surface reflectance, 30 meter spatial resolution, 16 day temporal resolution).
  • Land Use Data: 30 meter resolution land cover dataset for the Shiyang River basin (2002–2022).
  • Digital Elevation Model (DEM): ASTER GDEM dataset (30 meter resolution).
  • Observation Data: Field soil sampling (electrical conductivity and pH values) from 11 sites within the Shiyang River basin (2019–2024), and experimental field validation at Gulang County (2024).
  • Cross-validation Data: HWSD 2.0 data from the Food and Agriculture Organization (FAO).

Main Results

• The overall soil salinization area in the Shiyang River basin remained stable, but the degree of salinization intensified from 2002 to 2022.
• Salinization gradually increased from upstream to downstream, with the most severe salinization observed near Qingtu Lake in the downstream area.
• The northern hills and oasis–desert transition zone exhibited severe salinization (moderate and severe types), while the central corridor plain showed mild and moderate salinization, primarily in oasis farmland irrigation areas. The southern Qilian Mountain regions had lower risks of salinization.
• The total soil salinization area in the basin showed a slight overall increase, with the central corridor plain experiencing an increase of over 18% in salinization area by 2022 compared to 2002.
• Regional salinization problems were particularly prominent due to groundwater evaporation near reservoirs, agricultural irrigation evaporation, and downstream ecological water input evaporation.
• Human activities were identified as the decisive factor in changing the salinization pattern of inland river basins.
• Soil salinization around the Hongyashan Reservoir gradually intensified from 2002 to 2022. Groundwater electrical conductivity (EC) values near the reservoir consistently remained above 500 µS cm⁻¹ and increased by 14.119 µS cm⁻¹ from 2017 to 2023.
• In the short term, an expansion of irrigation area was often accompanied by a reduction in salinization area, while a decrease in irrigation area corresponded to an increase in salinization area, indicating a temporary leaching effect.
• In the long term, salinized lands were primarily distributed within irrigation areas, suggesting that prolonged over-irrigation coupled with inadequate drainage exacerbates soil salinization.
• The conversion rate of fallow land to saline land (7.11%) was significantly higher than for grasslands (5.68%) and cultivated lands (2.92%), highlighting high salinization risks without effective irrigation and salt elimination.

Contributions

• Provided a quantitative analysis of the spatial and temporal distribution characteristics of soil salinization in the Shiyang River basin over two decades (2002–2022) using remote sensing.
• Clarified the significant impacts of human activities, specifically water conservancy projects and agricultural irrigation, on the water cycle and subsequent soil salinization patterns in arid inland river basins.
• Offered a scientific basis for agricultural development, ecological construction, and water resource management planning in arid zones by identifying key drivers and high-risk areas of salinization.

Funding

• National Natural Science Foundation of China (grant nos. 42371040 and 41971036)
• Key Natural Science Foundation of Gansu Province (grant no. 23JRRA698)
• Key Research and Development Program of Gansu Province (grant no. 22YF7NA122)
• Cultivation Program of Major key projects of Northwest Normal University (grant no. NWNU-LKZD-202302)
• Oasis Scientific Research achievements Breakthrough Action Plan Project of Northwest Normal University (grant no. NWNU-LZKX-202303)

Citation

@article{Meng2025Soil,
  author = {Meng, Gaojia and Zhu, Guofeng and Jiao, Yinying and Qiu, Dongdong and Wang, Yuhao and Lu, Siyu and Li, Rui and Liu, Jiawei and Chen, Longhu and Wang, Qinqin and Huang, Enwei and Li, Wentong},
  title = {Soil salinity patterns reveal changes in the water cycle of inland river basins in arid zones},
  journal = {Hydrology and earth system sciences},
  year = {2025},
  doi = {10.5194/hess-29-5049-2025},
  url = {https://doi.org/10.5194/hess-29-5049-2025}
}