parking lot and several buildings. Such a change in the ground cover has a dramatic effect on the runoff, greatly increasing its total volume and the rate of runoff. This directly increases the potential fo analysis and design was often not performed. As a result, a significant amount of storm water damage now occurs, ranging from minor flooding of local streams, to erosion of farmland, to flooding of major rivers. The resultant burden on many drainage systems and the increasing rate of construction means tr erosion and flooding in all areas downstream of the new construction. To prevent such damage, the runoff must be predicted before construction so that suitable steps can be taken to handle the runoff in a safe and effective manner.In the past, suchhat all new construction and development should include a careful analysis of the effects on sto analysis and design was often not performed. As a result, a significant amount of storm water damage now occurs, ranging from minor flooding of local streams, to erosion of farmland, to flooding of major rivers. The resultant burden on many drainage systems and the increasing rate of construction means trm water runoff. when damage may occur. Steps can then be taken to reduce the chances of damage, such as enlarging a stream to prevent overflow of its banks, or detaining some of the runoff in a pond to reduce flooding downstream.Why is thHow i analysis and design was often not performed. As a result, a significant amount of storm water damage now occurs, ranging from minor flooding of local streams, to erosion of farmland, to flooding of major rivers. The resultant burden on many drainage systems and the increasing rate of construction means ts storm water modeled?Storm water modeling analysis and design was often not performed. As a result, a significant amount of storm water damage now occurs, ranging from minor flooding of local streams, to erosion of farmland, to flooding of major rivers. The resultant burden on many drainage systems and the increasing rate of construction means t can be divided into two basic fields: Hydrology, which is the study of runoff and the factors that influence it, and Hydraulics, which is the study of water flow in the channels, pipes, streams, ponds, and