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I I I I I I I I I , il I I I I I I I I il 5.0 INTERPRETATION OF TIllS REPORT 5.1 Hvdrololric Findimls The results of the hydrologic analysis for the White River are considered accurate. They are based in part on existing approved data. 5.2 Hvdraulic Findinl!:s The hydraulic methods used for this study are similar to those used in more detailed studies and much more detailed than the typical approximate studies. The 100-year flood depths range from 7.4 feet in a medium width reach of the river to 13.1 feet at the downstream limit of the study. The flood depths are generally consistent throughout the study reach with differences of a few feet (8-13 feet for 100-year flow depths). 5.3 Floodolain Delineations The primary difficulty in presenting precise delineation of the 50-year and 100-year floodplains was the limited quality of the available base mapping for the lower White River. Using USOS topographic quadrangle maps at contour intervals of 20 or 40 feet to portray flood lines in unsurveyed areas provides limited information. The margin for interpretation is very great, especially in wider reaches of the river where contours are widely spaced. More detailed topographic information will be needed in areas of specific interest. This study can be utilized to prepare more detailed floodplain delineations in such areas of specific interest. Those who are interested in greater detail have three choices for using this study: I) They can refer to the detailed study information for the stream reach in and around Rangely; 2) They can rely on the hydrologic determinations and use other topographic information and hydraulic models; or 3) They can use the depth calculations with other topographic information from field surveys or other maps. 22