Publication Details
Abstract
Secondary salinization is the principal form of land degradation in the irrigated lowlands of the middle Syrdarya basin, where shallow and mineralized groundwater, high evaporative demand and inefficient drainage combine to degrade soil quality. This study assesses the ecological properties of saline soils in the Syrdarya region of Uzbekistan by integrating field and laboratory soil analyses with remote sensing and geographic information system (GIS) techniques. A total of 120 georeferenced soil samples were collected from the eight rural districts of the region and analyzed for electrical conductivity of the saturation extract (ECe), pH, chloride and sulfate content, sodium adsorption ratio (SAR) and humus. Four spectral indices (SI, NDSI, VSSI and NDVI) were derived from Sentinel-2 MSI imagery and combined with groundwater table (GWT) depth and groundwater mineralization in a multiple linear regression model; residuals were interpolated by ordinary kriging. The regression-kriging model achieved a validation coefficient of determination of R² = 0.70 and a root mean square error of 1.80 dS m⁻¹. Approximately 92.2% of the surveyed irrigated area was saline to some degree, with 35.4% moderately, 13.1% highly and 2.2% extremely saline. A Soil Ecological Condition Index (SECI), weighted by the analytic hierarchy process, ranged from 0.34 in Mirzaobod to 0.61 in Boyovut and revealed a clear north-east to south-west gradient of deterioration associated with shallow, mineralized groundwater in the Mirzachul (Hungry Steppe) part of the region. The proposed GIS framework provides a reproducible basis for district-level prioritization of drainage rehabilitation, leaching regimes and salt-tolerant cropping.