This book is based on the accepted papers for presentation at the 2nd MedGU Annual Meeting, Marrakesh 2022. It presents a series of newest research studies that are nowadays relevant mainly to Middle East, Mediterranean region, and Africa. It includes major subjects related to hydrology, hydrogeology, hydrogeochemistry including, but not limited to, isotope hydrology, groundwater models, water resources and systems, and related subjects. It also includes research studies on biogeochemistry which mainly focus on the interactions between life and the chemical cycles in the Earth system. Some case studies on geobiology and geoecology investigate the structure and function of geoecosystems, their components, and their environment. The book also presents major subjects related to atmospheric, oceanic, meteorology and climatic science with recent developments in the field. By cutting across these traditional subject boundaries, this book brings together the major elements that are important for understanding the weather, climate, water systems, and geoecosystems in these regions.