This edited book gives a general overview on current research, focusing on geoenvironmental issues and challenges in hydrogeosciences in model regions in Asia, Europe, and America, with a focus on the Middle East and Mediterranean region and surrounding areas. This proceedings book is based on the accepted papers for oral/poster presentations at the 2nd Springer Conference of the Arabian Journal of Geosciences (CAJG-2), Tunisia 2019. It offers a broad range of recent studies that discuss the latest advances in geoenvironmental and hydrogeosciences from diverse backgrounds including climate change, geoecology, biogeochemistry, water resources management, and environmental monitoring and assessment. It shares insights on how the understanding of