HEC-HMS (Hydrologic Engineering Center's Hydrologic Modeling System) is a software program developed by the U.S. Army Corps of Engineers for simulating the hydrologic processes of watersheds. It helps engineers and planners analyze rainfall-runoff relationships, assess flood risks, and design water management systems. The program allows users to model various hydrologic components, including precipitation, evaporation, infiltration, and surface runoff. By providing tools for data input, simulation, and output analysis, HEC-HMS supports effective decision-making in water resource management and environmental protection.