An Integrated Climate and Water Stress Index for Index-Based Insurance of Irrigated Agriculture: Development and Validation in the Shu-Talas Water Management Basin, Kazakhstan

In the context of increasing climate variability, the assessment of risks to irrigated agriculture requires a combined consideration of climatic and water management factors. The aim of this study is to develop an Integrated Climate and Water Stress Index (ICWSI) and to assess its potential applicability in index-based insurance. The study was conducted for the Shu-Talas Water Management Basin in Kazakhstan for the period 2000–2024. The ICWSI combines the Standardized Precipitation and Evapotranspiration Index (SPEI) with the actual annual Water Abstraction Index (WAI) for regular irrigation. Correlation analysis, RMSE, MAE, LOOCV cross-validation, ROC analysis and basis risk metrics were used to evaluate the index. It was found that the relationship between climatic drought and agricultural productivity was weak, whilst annual water abstraction was characterized by a more pronounced statistical relationship with its interannual variability. ICWSI values ranged from −1.64 to +1.70, reflecting differences in the combination of climatic and water management conditions. The results of the insurance validation revealed a trade-off between the completeness of identifying years with reduced productivity and the frequency of false positives. The Area Under the Curve (AUC) values obtained indicate that the indices under consideration have limited discriminatory power. The proposed approach enables the joint characterization of climatic and hydrological conditions in a regulated transboundary catchment. Its application as a standalone insurance trigger requires further validation using a dataset of independent data and refinement of the threshold values.