Hydrometeorology is a branch of meteorology and hydrology which the transfer of water and energy between the land surface and the lower atmosphere especially precipitation. Some hazards associated with hydrometeorology are floods, tropical cyclones, drought and desertification. Hydrometeorology is the scientific study of the interaction between meteorological and hydrologic phenomena, including the occurrence, motion, and changes of state of atmospheric water, and the land surface and subsurface phases of the hydrologic cycle. Considerable emphasis is placed on determining, theoretically or empirically, the relationships between meteorological variables and the maximum precipitation reaching the ground. These analyses often serve as the bases for the design of flood-control and water-usage structures, primarily dams and reservoirs.