Assessing the Interaction Between Agricultural, Hydrological, and Meteorological Droughts in the Tigris River Basin

Drought is a common meteorological phenomenon that can result in a range of adverse outcomes. The Tigris River Basin (TRB) is located in the arid and semi-arid regions of southwestern Asia, where drought conditions have been observed to intensify. This research aims to understand the relationship between agricultural, hydrological, and meteorological droughts in the basin. To examine meteorological, agricultural, and hydrological droughts, the study employed three indicators: the Standardised Precipitation Index (SPI), derived from Terraclimate precipitation data; the Tasselled Cap greenness index, calculated from Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) multispectral imagery; and surface water area fluctuations based on the MODIS Terra Daily normalised difference water index (NDWI). Our analysis of monthly SPI data from 2003 to 2022 indicates that approximately half of the months experienced meteorological drought conditions. The occurrence of agricultural drought was found to be associated with both 6-month and 21-month accumulation periods of SPI values, underscoring the intricate interrelationship between precipitation deficits and other influential factors in the context of agricultural drought. Hydrological droughts demonstrated significant correlations with meteorological droughts over accumulation periods of 1, 3and 15 months, indicating a rapid onset but prolonged impact on water resources. Our findings indicate that although the various types of drought are interconnected, their relationships are not straightforward. Further research is required to explore the factors driving these patterns.