Climate change adaptation measures are essential to increase the resilience of cities and reduce hazards. Reliable measures combine infrastructure and nature-based solutions, but accurate urban water-balance studies remain as the foundation for land-use development initiatives and regulations. Floods, droughts, and water quality aspects are hazards due to climate change and show a close link to groundwater. Consistent stormwater management practices can be used to cope with both floods and droughts. The urban water balance underpins a holistic understanding of water dynamics in cities, informing sustainable resource management practices, increasing resilience to climate change impacts, managing flood risks, protecting water quality, informing infrastructure and land-use planning, and promoting economic benefits. Hydrogeological monitoring and modeling of urban environments encompass diverse applications in civil and environmental engineering and can be developed when a solid scientific basis is needed to optimize management and forecasting. The key challenge lies in identifying the causes and time variation of groundwater fluctuations. Urban groundwater modeling, mapping, and data visualization are used in decision making with different levels of complexity. Models require detailed representation of the spatial and temporal domains and maps represents a fundamental tool for effective communication between specialists and different stakeholders to analyze, discuss, and make informed decisions.