Comparative analysis of NDVI and CHIRPS-based SPI to assess drought impacts on crop yield in Basrah Governorate, Iraq

Drought is a climatological phenomenon that occurs across all climate zones of the world. It causes environmental and economic loss and can negatively affect agricultural profit, especially in dry and semi-arid areas. This study used the Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) to model drought impacts on agricultural production. The role of meteorological and hydrological parameters was considered simultaneously. The results revealed that: (1) the increase of drought intensity leads to the reduction of crop production, while in the case of high-level drought, the production stays consistent; (2) NDVI could model the impacts of drought on crops production (R2 = 0.60 and RMSE = 0.42); (3) NDVI had a better ability for showing SPI fluctuations, but in higher drought intensities, it was less sensitive to SPI fluctuations; (4) the spatial pattern of drought in the study area showed that the northern parts of the Basrah Governorate have the highest sensitivity to drought; (5) the temporal pattern of long-term SPI showed a high level of risk for agricultural activities due to drought; and (6) air temperature and humidity are the main meteorological parameters of crops production affecting the interpretation of the impacts of drought on agriculture production in Basrah, Iraq.