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<br />General Methods (Of Engineering Flood Hydrology <br /> <br />There are four g<:meral methods of analysis employed in engineer- <br />ing flood hydrology. In principle, the four general methods <br />discussed herein are equally applicable to the urban and rural <br />setting, however, statistical analysis of flow data is more <br />typically used in the rural watershE,d owing to the fact that land <br />use is less likely to change during the period of data acquisi- <br />tion in the rural watershed than in the urban watershed. statis- <br />tical analysis of rainfall data is equally applicable to the <br />rural and urban .ratershed and the results of rainfall statistical <br />analysis are applied to the Desiqn s-torm Concept:. <br /> <br />One of the fundamental principles of flood flow hydrology has to <br />do with the relationship between watershed drainage area and <br />flood peak discharge for a given excleedance probability. General- <br />ly speaking, there is a non-linear relationship between flood <br />peak discharge of a given exceedance probability and drainage <br />area. In general, there is a tendency for a smaller drainage <br />area that is a part of a large watershed to produce a higher <br />discharge per un:Lt of drainage than would a larger drainage area <br />with the same wat;ershed. This conce'pt is import;ant because there <br />may be a tendency on the part of the beginner in hydrologic <br />analysis to establish a linear n,lationship hetvleE!n drainage area <br />and peak discharge. <br /> <br />The following discussion of four general methods of flood fre- <br />quency analysis l:eflects my own thinking on t;he subject. Others <br />may have different ways of classifying the gEmeral approaches to <br />flood hydrology. <br /> <br />~ <br /> <br />3 <br />