Laserfiche WebLink
<br />. <br /> <br />dl Floodplain Delineations and Datum Consistency <br /> <br />. <br /> <br />The next step of the floodplain study is the delin- <br />eation of the flood limits on the topographic maps <br />(see Figure ). Delineation requires the depiction <br />in plan view of the information which is shown in <br />vertical view on the flood water surface elevation <br />tables and profiles. The plan view provides a <br />clearer picture of the extent of actual flooding at <br />specific locations along the stream. Maintaining <br />consistency is very important to developing a tech- <br />nically and legally acceptable regulatory document <br />which can be incorporated into floodplain regula- <br />tions and/or zoning maps. Many delineations have <br />lacked this internal consistency. Problems may be <br />eliminated through improved reporting and interpre- <br />tation procedures. <br /> <br />-27- <br /> <br /> <br />The procedure which the ewCB recommends for delinea- <br />tion of the 100-year floodplain on topographic maps <br />is as follows: <br /> <br />o <br /> <br />using the hydraulic analysis, the flood eleva- <br />tions at each cross-section are tabulated. <br />The flood profiles are drawn. <br />Channel centerline stationing from the water sur- <br />face profiles at the whole numbered flood eleva- <br />tions corresponding to the base contour interval <br /> <br />o <br /> <br />o <br /> <br />. <br />