Storm water is water which originates during precipitation events and snow. Storm water management modeling is a dynamic rainfall–runoff–subsurface runoff simulation model used for single-event to long-term simulation of the surface hydrology quantity and quality from primarily urban areas. Snow hydrology is a scientific study in the field of hydrology which focuses on the composition, dispersion, and movement of snow and ice. Studies of snow hydrology predate the Anno Domini era, although major breakthroughs were not made until the mid -eighteenth century. Stream hydrology deals about the flow of water in streams, rivers and other channels and is major element of water cycle and the water flow in channels come from surface run off from adjacent hilly slopes from ground water flow out of ground and discharge into pipes ,floods may occurs when water levels are increased than its capacity.