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 ecological, climatological, oceanic and hydrological processes is the key for improving practices in environment management, including the eco-responsibility, scientific integrity, and social and ethical dimensions. It is of interest to scientists, engineers, practitioners, and policymakers in the field of environmental sciences including climatology, oceanography, ecology, biogeochemistry, environmental management, hydrology, hydrogeology, and geosciences in general. In particular, this book is of great value to students and environment-related professionals for further investigations on the state of Earth systems.