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<br />OJ133J <br /> <br />2 <br /> <br />Technical - There are numerous published techniques -- rainfall- <br /> <br /> <br />runoff models -- that are "suitable" for computing watershed discharge <br /> <br /> <br />in an urbanizing environment (17, 24, 33, 36,89). Unfortunately, they <br /> <br /> <br />all yield different discharges. These differences can be quite large; <br /> <br />in one instance the 100 year discharge for a basin in Lolorado using one <br /> <br /> <br />method was twice the value computed using another.l These differences <br /> <br />in discharge result, in turn, in different designs and different eco- <br />nomic analyses. In developing a drainage,management program, the muni- <br />cipal engineer must decide which technique offers his community the <br /> <br />"best" flood hydrology prediction capabil ity. <br />The literature in this area will not help the municipal engineer <br /> <br />make this decision. He will find reports of demonstrated uses of, and <br /> <br /> <br />problems associated with the various rainfall-runoff models (17, 63, 75, <br /> <br /> <br />109). However, his real concern -- the predictive capability of these <br /> <br /> <br />models -- will not be answered. The reports of model comparisons (0) <br /> <br />are far from conclusive and offer little assistance in selecting an <br /> <br /> <br />appropriate rainfall-runoff model. <br /> <br /> <br />Financial - Drainage management is not cheap. The limited budget- <br /> <br /> <br />ing for the drainage sector must be augmented with other funds. The <br /> <br />municipal engineer must first estimate the cost of needed drainage and <br /> <br />flood control facilities. He then has to devise a method for equitably <br />and legally collecting money to pay for these facilities. <br />The literature in this area is helpful but not complete. The <br />municipal engineer will find reports on project evaluation methods (40), , <br />drainage facility financing alternatives (12), cost allocation <br /> <br />lEndnotes begin on page 160. <br />