This chapter explores the intricate interplay between geology, hydrology, and environmental evolution in Qatar, emphasizing how these natural systems have shaped the region’s past, present, and future. Qatar’s surface geology is dominated by Eocene and Miocene carbonate formations, influenced by tectonic uplift and evaporative sedimentation in the Arabian Gulf. The peninsula’s aquifers, primarily composed of Paleogene carbonates and evaporites, reflect a complex depositional history shaped by marine incursions and tectonic structures. Quaternary sea-level fluctuations and climatic shifts have significantly influenced coastal geomorphology, with evidence of ancient shorelines and paleo-lakes. Key landforms such as sand dunes, wadis, sabkhas, and caves illustrate the dynamic interaction of wind, water, and geological substrates in shaping Qatar’s arid landscape. The chapter also highlights the critical role of geosystem services in supporting biodiversity and sustaining life in desert ecosystems. These include water regulation, erosion control, and nutrient cycling, with particular attention to the ecological value of mangroves, wetlands, and coral reefs. Qatar’s water resources, heavily reliant on desalination and limited groundwater, face challenges from over-extraction, salinization, and brine disposal. The chapter underscores the importance of sustainable water management, including treated sewage re-use and managed aquifer recharge, to mitigate environmental impacts. Recommendations include promoting geological research, understanding past sea-level changes, improving water governance, and assessing the ecological consequences of water-related practices. These insights are vital for guiding Qatar’s environmental policy and ensuring resilience in the face of climate change and rapid development.