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<br />alternatives are viable only for areas that are not yet developed. A <br />recent study (l3) presents data on costs and performance for a variety of <br />these upstream alternatives. <br />The .results of a recent study (14) provides an illustration of the <br />performance that may be expected from upstream adjustments. By making use <br />of roofs designed with a top ring that would encourage storage, elevated <br />plazas and parking garages for storage space, open grassy depressions and <br />swales, it is possible to temporarily store stormwater on about 45% of <br />the area within a low density residential location. The result is a <br />predicted reduction in peak flow of approximately 33% for the 100-year <br />event. By including the detention storage in swales along roads and <br />contouring open space areas, an additional 38% reduction in peak flow is <br />predicted. The author forecasts overall lower costs for storm drainage <br />and public and private development. Implementation is almost exclusively <br />a local non-federal prerogative. <br />Physical works would be easy to implement if the various publics and <br />institutions were agreeable. The effort in planning these facilities revolves <br />al~und assuring performance while accommodating the wishes of interested <br />publics. On the other hand, the nonstructural alternatives have the <br />characteristic that they are extremely difficult to implement even when <br />a majority decision as to the desired course of action is in hand. <br /> <br />Nonstrllctural Alternative <br />Nons tructura 1 a lternati ves incl ude all management activities that are <br />designed primarily to control people and reduce the incidence of damage <br />and points of conflict in the flood plain. Some chose to label these <br />24 <br />