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<br />ponds, or other man-made flood control facilities are present. Effects from non flood control <br />reservoirs may be ignored in hydrology studies utilizing these Guidelines. Users must take <br />caution when using the Guidelines in watersheds having unusual drainage characteristics. <br /> <br />. The regression equations were developed using IOO-year flow values which were obtained from <br />published FEMA and other floodplain studies. The flow values in those previous studies were <br />developed using different hydrologic methods such as flood frequency analyses of streamflow <br />gaging station data and rainfall-runoff models, <br /> <br />. 1bis publication is for use with streams having no floodplain information or approximate <br />floodplain information only. It is not to be used for the preparation of detailed studies, for the <br />design of hydraulic structures, for the evaluation of ditch and canal overflows, or for the <br />evaluation of local storm drainage and ponding problems, A detailed hydrologic and hydraulic <br />analysis should be performed for those cases and for any planned development involving <br />residential subdivisions, commercial structures, industrial structures, public facilities (roads, <br />bridges, treatment plants, etc.), and flood control facilities. <br /> <br />. A detailed floodplain study will supersede a study that was performed using this publication. <br /> <br />. The subregional boundaries shown on the maps in this document for each major basin may be <br />difficult to interpret due to the scale of the mapping. Study reaches that lie on or near a <br />subregional boundary will require careful interpretation. In those cases, the CWCB may be <br />contacted to assist in making a boundary determination. <br /> <br />1.2 METHODOLOGY <br /> <br />The fIrst step in the development of the Guidelines was to collect existing hydrology information <br />from all of the designated or soon to be designated Colorado floodplain studies (detailed) within the <br />CWCB's floodplain information library. The state was divided into major drainage basins, and the <br />available data was grouped by basin. The major basins, which are graphically presented in fIgure I, <br />are as follows: <br /> <br />1. Arkansas River 6. Dolores River <br />2. South Platte River 7. San Juan River <br />3, Republican River 8, Rio Grande <br />4, Colorado River 9, North Platte River <br />5. Green River <br /> <br />3 <br />