Linking Drought Index-Based Metrics to Real-World Impacts for Enhanced Monitoring in the Tensift River Basin, Morocco

Drought is a natural disaster causing the greatest global losses and having the most significant impacts across various sectors. In the Mediterranean region, particularly in the Tensift River Basin, Morocco, drought severely affects water availability, agriculture, and local economies. Despite its importance, traditional monitoring systems often fail to provide timely warnings or accurately quantify and report drought impacts. This study evaluates the performance of the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) in detecting drought events, focusing on optimizing thresholds and timescales to enhance monitoring accuracy. Using Receiver Operating Characteristic (ROC) analysis, we assessed the correspondence between estimated drought events and reported impacts, achieving AUC values of 78.34% for SPI and 68.32% for SPEI. These results highlight the strengths of both indices in detecting drought onset and duration while addressing limitations such as sensitivity to PET methods. The findings emphasize the importance of tailoring thresholds, timescales, PET models, and probability distributions to local climatic conditions. The proposed framework is crucial for mitigating drought impacts and supporting decision-makers in sustainable water resource management in the Tensift Basin. Additionally, this research underscores the need for systematic reporting of drought impacts to inform the development of comprehensive drought atlases and regional management strategies.

Keywords: Drought Impact, ROC Analysis, Threshold Optimization, Drought Risk, Climate Change