GIS-BASED ASSESSMENT OF IRRIGATED AGRICULTURAL LAND PRODUCTIVITY USING SENTINEL-2 NDVI, ESBK, AND FDEI INDICATORS: A CASE STUDY OF SARYAGASH DISTRICT, TURKESTAN REGION, KAZAKHSTAN
Abstract
Background and significance. The effective management of irrigated agricultural land in arid areas depends on timely spatial information on crop condition and economic performance at the level of individual cadastral parcels. In practice, conventional land administration systems usually do not contain such operational data. As a result, decisions on irrigation scheduling, fertiliser application, and land reclamation are often made uniformly across fields, despite substantial spatial differences in land quality and productivity. This reduces both agronomic and economic efficiency. Methods. The study combined Sentinel-2 satellite imagery with digital cadastral boundaries to evaluate irrigated farmland in the Saryagash district of Turkestan Region, Kazakhstan, during 2023–2024. NDVI values were derived from Sentinel-2 imagery acquired on 14 June 2024 under cloud cover below 5 %, using bands B8 and B4 with a spatial resolution of 10 m. The processing and spatial analysis were carried out in QGIS 3.28. Two composite indicators were applied across ten irrigated farms with a total area of 371 ha. The Estimated Sowing Potential Coefficient (ESBK) was used to characterise land suitability by integrating soil quality, moisture availability, and salinity risk. The Farm Decision Efficiency Index (FDEI) was used to assess the economic viability of production by comparing gross revenue with total production costs per hectare; values above 1.0 indicate profitable farming. Results. The analysis showed considerable spatial variation among the studied farms. NDVI values ranged from 0.36 to 0.82. Two farms were identified as priority areas for reclamation, with ESBK values of 0.11–0.13, while three farms demonstrated relatively high land potential, with ESBK values of 0.50 and above. Farms with NDVI values of at least 0.70 consistently showed stronger economic performance, with FDEI values between 1.47 and 1.60 and net profits of 400–560 thousand KZT per hectare.