Groundwater dynamics in the Komaduga-Yobe basin: modeling 20 years of historical trends to forecast future scenarios (2020–2040)

The Komadugu-Yobe River Basin (KYRB) in northeastern Nigeria is a critical resource for agriculture, domestic water supply, and ecosystem sustainability. However, the basin faces severe threats from agricultural intensification, unregulated irrigation, and climate-induced stressors. This study investigates the impacts of agricultural practices and climate change on groundwater levels, recharge rates, and salinization within the KYRB from 2020 to 2040. Using a multidisciplinary approach that integrates MODFLOW simulations, the study analyzes historical climatic trends (2000–2020) and projects future scenarios under Representative Concentration Pathways (RCP 4.5 and RCP 8.5). Results reveal significant groundwater level declines in key locations, including Gashua (−2.1 m), Hadejia (−1.8 m), and Nguru (−2.0 m). Recharge rates are projected to drop by up to 20 mm/year, while salinity levels could increase by over 50 µS/cm, reducing water usability for agriculture and domestic needs. Climate variability in the study area is pronounced, with temperatures rising by approximately 4 °C between 2000 and 2020 and a further 2–3 °C increase projected by 2040. Concurrently, average humidity levels have declined by 10% over the past two decades, with an additional 5–7% reduction expected by 2040. These climatic shifts, combined with inefficient irrigation methods and the cultivation of high-water-demand crops, exacerbate groundwater depletion and salinization, posing significant risks to water security and agricultural productivity in the region. These findings are critical for policymakers, water resource managers, and agricultural stakeholders, highlighting the urgent need for adaptive strategies to mitigate groundwater depletion and salinization. This study recommends adopting efficient irrigation technologies, enhancing aquifer recharge through managed techniques, implementing policies to regulate groundwater abstraction, promoting drought-resistant crops, and restoring natural flood regimes.