Integrated Geospatial Assessment of Climate-Driven and Satellite-Based Vegetation Indicators for Agricultural Drought Monitoring

Abstract

Agricultural drought has become an increasingly significant environmental challenge because of ongoing climatic variability and rising atmospheric water demand. Reliable identification of drought conditions is therefore essential for sustainable agricultural production, environmental management, and regional adaptation planning. This study presents a geospatial framework for evaluating the performance of meteorological and remotely sensed vegetation indicators in monitoring drought conditions across Samsun Province, Türkiye. Meteorological variables were obtained from the CHIRPS precipitation archive and NASA POWER climate database, whereas vegetation characteristics were extracted from MODIS imagery. Four meteorological drought indicators, including the Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), Agricultural Standardized Precipitation Index (aSPI), and Effective Reconnaissance Drought Index (eRDI), were evaluated together with six vegetation indices consisting of NDVI, EVI, RDVI, TVI, SAVI, and OSAVI. Comparative statistical analysis demonstrated that the enhanced eRDI produced the highest agreement with agricultural drought conditions, yielding a correlation coefficient of 0.82, while NDVI represented vegetation stress most consistently with a correlation coefficient of 0.78. Spatial analyses revealed that vegetation degradation was most pronounced during the 2002–2003 drought period, whereas vegetation recovery became evident under wetter climatic conditions during 2020–2021. The integrated assessment confirmed that combining meteorological and satellite-derived indicators provides a more comprehensive representation of drought evolution than relying on a single dataset. The proposed methodology offers a practical decision-support framework for agricultural drought monitoring, climate adaptation, and sustainable resource management in humid coastal environments.