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<br />ACKNOWLEDGMENT <br /> <br />The research results presented herein were sponsored jointly by the Colorado State University Experiment <br />Station under Proj ect 114 and the Hydrologic Engineering Center, U.S. Corps of Engineers. Davis. California under <br />Contract DACWO 5-73-C-0029. Dr. Arlen Feldman was the technical monitor of the proj ect representing the Hydrologic <br />Engineering Center. The assistance of the Hydrologic Engineering Center in use of the HEC 1 computer program is <br />gratefully acknowledged. Since Mr. Lopez completed his thesis work, an improved version of the HEC 1 computer <br />program has been used in deriving the unit hydrographs. The authors wish to acknowledge the assistance of <br />Mr. Y.H. Wu and Mr. Todd Shimada in carrying out the recomputation of the unit hydrographs. <br /> <br />ABSTRACT <br /> <br />A brief review of previous work is presented. Different methods for quantifying urbanization are discussed. <br />A stepwise multiple regression technique was used to select the best parameter of urbanization. The rainfall and <br />flo~d events from nine urban watersheds in the Denver Metropolitan region were analyzed. Unit hydrographs were <br />derlved ~rom the measured floods on these watersheds. The unit hydrograph parameters were correlated with storm <br />and physlcal watershed p~rameters. It was found that the changes in the unit hydrograph in the urban region were <br />r:lated to the de:rease 1n the watershed :e~ponse time: The best way of defining the response time was the lag <br />tlme. The lag tlme was found to be sensltlve to the lncrease in the hydraulic capacity to the decrease in the <br />ratio of pervious watershed and th0 shape of the watershed. <br /> <br />Chapter 1 <br />INTRODUCTION <br /> <br />There are many problems related to hydrology <br />which plague the present day city engineer. One of <br />these is related to flood hydrology and the design <br />of storm water drainage. Water courses through the <br />urban region which previously were apparently of <br />adequate capacity chronically suffer the symptoms of <br />under capacity after urbanization has taken place. <br /> <br />Accompanying this frequent flooding problem is <br />the tendency for the water courses to deteriorate, <br />become unsightly dumping grounds and to become the <br />beginnings of urban blight. <br /> <br />The problems of sedimentation--both channel scour <br />and channel degradation at various points along the <br />remaining drainageways--are in turn related to the <br />higher incidence of floods in the urban channel reaches. <br />To document these facts, the U. S. Geological Survey <br />has undertaken a program to measure the floods on urban <br />watersheds throughout the country. The American Society <br />of Civil Engineers has acted as an agency to assemble <br />and disseminate data and results of the information <br />obtained from urban floods. There have been several <br />research projects which have developed correlations be- <br />tween the flood hydrograph parameters and various phys- <br />ical features unique to the urban watershed. <br /> <br />1 <br />