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<br />~" <br /> <br /> <br />~\. <br />" , <br />, <br /> <br />(,' <br />" <br /> <br />" ~ <br /> <br />Poi nt 1 <br /> <br />,8640 <br /> <br />ds <br /> <br />" <br /> <br />", <br /> <br />2 <br /> <br />8680 <br /> <br />ds <br /> <br />3 <br /> <br />, 8000 <br /> <br />ds <br /> <br />The reason for a smaller flow at point 1 which is downstream of point <br />2 is that for a very small percentage increase in watershed area, there is <br />a larger percentage increase in the length of travel(time of concentration) <br />of the flood. This type of fluctuation is common when the study points are <br />not too far apart. <br /> <br />The flood plain was delineated on the detail (1" = 100') topographic <br />map and is based on the c.;hannel water-carrying capacity determined by <br />the classic Manning formula in which an average rOllghness coefficient of <br />0.030 was llsed. This is iatended tu allow for thc"""eedy and meand~ring <br />parts of the channel. " <br /> <br />From the cross sections oa the exhibits it can be seen that in the event <br />of the 100 year flood the water can be expected to rise to 6424 at point (1), <br />6438 at point (2), and 6458 at point (3). <br /> <br />SUGGESTIONS FOR FLOOD PLAIN MANAGEMENT <br /> <br />There appear to be ao existing problems affecting the Town of Elizabeth <br />and directly related to the flood plain defined in this study. As a specific <br />example, it a.ppears that even the sewage treatment facilities would not be <br />flooded by the 100 year flood. The wells currently llsed by the Town of <br />Elizabeth are located on high grollnd away from Running Creek and not <br />affected. <br /> <br />This however is not to say that problems could not develop. The best <br />possible way to avoid sllch potential problems will be to use the most <br />common tools to that end and some of them are incorporated in the US <br />Corps of Engineer "Guidelines for Flood Plain Management". Quoting <br />from that work we list the following recommendations: <br /> <br />1. ,Zoning as a prerogative of a municipality can reduce tile potential <br />flood hazard area. <br /> <br />2. Sllbdivision reglllations can set street widths. storm drain reqllire- <br />ments and minimllm standards, lot sizes, elevations, other <br />limitations in haza rd areas. <br /> <br />3. Building codes can and should inclllde flood-proofing criteria. <br /> <br />-5- <br />