A comprehension of the diversity of water resources and hydrological characterization of Kerala is of utmost importance for sustainable management of the water resources and conservation of the aquatic environment. The reliance on the water resources of Kerala for agriculture, power generation, industry and tourism sectors underscores the critical importance of the hydrological characterization. Within this chapter, an in-depth exploration of the hydrological setting of Kerala is undertaken, which covers the physical environment, rivers, watersheds, climate and hydrological disasters, as well as the challenges to sustainable water resource management. The hydrological data presented in this chapter and their synthesis establish a solid foundation for researchers, planners and decision-makers to remodel efficient water management and planning strategies. It also serves as a valuable platform for developing robust disaster management plans, early warning systems and adaptive strategies aimed at enhancing climate resilience and minimizing the socio-economic impacts linked to hydrological disasters.