Development of the Niger Basin Drought Monitor (NBDM) For Early Warning and Concurrent Tracking of Meteorological, Agricultural and Hydrological Droughts

Drought remains a phenomenal disaster of critical concerns in West Africa, particularly in the Niger river Basin, due to its insidious and multifaceted nature. Its continuous devastating impacts on communities, coupled with the limitations of existing univariate index-based monitoring approaches contributes to the problem. The paper aims to introduce and evaluate a Hybrid Drought Resilience Empirical Model (DREM) that integrates meteorological, agricultural, and hydrological drought indicators to enhance their concurrent monitoring and early warning in the region for effective decision-making. The datasets used include reanalysis hydrometeorological records from 1980 - 2016, and community-level vulnerability data. Results show that DREM-based composite index detects drought earlier than SPI-based indices, with higher agreement to soil moisture and streamflow. The model detects drought initiation when the drought thresholds are of the range -0.26 to -1.19 over a period of three consecutive months depending on the location. The end of droughts occurs when thresholds are higher and of the range of -0.08 to -0.82 depending on the location. Thus, based on the findings of this study, the DREM-based composite index has indeed proven to be a suitable drought monitor for the Niger Basin and early warning tool decision-makers and stakeholders can trust with high confident.