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<br />. <br /> <br />. <br /> <br />. <br /> <br />I. Introduction <br /> <br />This report summarizes the methodology and assumptions used in the <br />hydraulic analysis of the 1989 paoli flood and channel improvements <br />developed to reduce flooding in the town of Paoli. <br /> <br />A. HEC-2 <br /> <br />The hydraulic analysis of the July 30, 1989 <br />flood event was conducted using the Corps of Engineers HEC-2 <br />computer program. HEC-2 is intended for calculating water surface <br />profiles for steady gradually varied flow in natural or man-made <br />channels. The computational procedure is based on the solution of <br />the one-dimensional energy equation with energy loss due to <br />friction evaluated with Manning's equation - generally known as the <br />Standard Step Method. The supplementary program, PLOT2, was also <br />used in the flood study to verify cross section geometry, water <br />surface profiles and channel modifications geometry. <br /> <br />II. Existina Conditions (aeneral approach and reaches) <br /> <br />To a large extent, the accuracy of HEC-2 generated water surface <br />profiles depends on the detail of topography since HEC-2 computes <br />effective water-way flow areas based on cross section horizontal <br />and vertical coordinates. <br /> <br />A. Ground Survey <br /> <br />A field survey was conducted in order to determine the existing <br />ground surface profile of each selected cross section and the <br />thalweg elevations. Elevations of major control structures such as <br /> <br />Paoli Flood Study <br />September 29, 1991 <br /> <br />Hydraulic Analysis Report <br /> <br />-2- <br />