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Table 3. 1-H':lur Precipitation Depth for Denver, Colorado Return Period (years) . 1-Hour Precipitation Depth (inches) 2 0.95 5 1.35 10 1.65 50 2.2 100 2.6 HARVARD GULCH The selection process for a representative urban drainage basin focused on two key elements. The first element was the obvious need for significant rainfall-runoff data over a relatively long period. The second element was to find a small to medium sized basin between 1 and 5 square miles. Harvard Gulch satisfied both of these criteria and was selected for this investigation (see map 1). Harvard Gulch has been the subject of many hydrological studies. As a result there is an abundance of information available. Harvard Gulch is a relatively small drainage basin located in south central Denver, Colorado. The drainage basin characteristics were determined using a combination of topographic maps (1 :24,000 scale), physical observation, and published literature. It should be noted that published literature frequently disagreed appreciably on basic parameters for this basin (notated where applicable) and values calculated by the author were used in most cases. Harvard Gulch is an oblong (football shaped) basin with an area of 2.93 square miles and a length-to-width ratio of approximately 2.5. The basin is approximately bounded by Evans Avenue to the north, Highway 1-25 to the east, the Highline Canal to thE! south, and Harvard Gulch Park to the west. The surface area of the basin was the parameter that showed the greatest variance in the literature, ranging from 7.34 square miles (Gingery Associates, 1978) to 3.10 square miles (Zarriello, 1998). The author found that the overestimation of the surface area was due to incomplete knowledge of the basin characteristics. Harvard Gulch has three primary catchments: (1) the central basin that runs the length of Harvard Gulch (the subject of this study), (2) a basin south of Harvard Gulch which is a tributary to Harvard Gulch before it enters the South Platte River (Englewood Tributary), and (3) an eastem basin section whose flow is intercepted by the Highline Canal. The stream flow gaging station for the basin in this study is located on Harvard Gulch prior to the confluence of the southern basin tributary and is therefore not included in the computations. As stated previously, the eastern basin's flow is wholely captured by the Highline Canal and is not included. The basin length from the stream flow gaging station to the farthest reach along the drainage pathway is 3.46 miles. The distance to the centroid is 1.73 miles. The elevation at the headwaters of the basin is 5480 feet Application and Evaluation of CUHP Page 6 of 52