Introduction

Flash floods are one of the most difficult to predict of natural disasters. Much work has been done to pin down some essential environmental clue that the sky will open up and loose upon a community a deluge . To date, however, no effective means has been devised to predict when and where, in exact terms, a flash flood will strike. Thus, people in communities that have developed floodplains, which includes most parts of the United States, and verily, the wo rld, have little in the way of defense against severe flooding. However, it can be said that some communities have developed their floodplains wisely. That is to say, they have removed structures from the floodplain and attempted to create a zone of saf ety around streams and rivers. However, this has not always been entirely effective, as in the case of the July 28, 1997 flood of Spring Creek in Fort Collins, Colorado. Unfortunately for the residents of two mobile home parks along Spring Creek, as wel l as hundreds of other homeowners and businesses near the watercourse, the flood hazard mitigation plans of the city of Fort Collins were not enough to prevent damage and destruction.

Urbanization of drainage basins presents problems that are not easily overcome. Both Colorado Springs and Fort Collins face many problems concerning flash flooding as both cities have several drainage basins that can be characterized as urban. Urbanization has three major effects on urban flooding. First, the creation of impermeable surfaces inhibits infiltration so that storm rainfall appears as runoff. Thus, small floods may be intensified by as much as ten t imes by urbanization and the 100-year event may be doubled in size by a 30% paving over of the basin (Smith 266). Secondly, urbanization of watersheds causes channelization and pollution of the stream, which further degrades the ability of a channel to c ontain a flood (Hill 69). Thirdly, streets and parking lots are serviced by a network of surface drains and underground sewers, which deliver water more rapidly to the local channel. This has the effect of reducing the lag time between initial rainfall and the onset of flooding. Additionally, the channel is often constricted by bridge supports or riverside structures, thus reducing the carrying capacity of the stream. This increases the frequency with which high flows overtop the riverbanks (Smith 266 ).

From the perspective of the city of Colorado Springs, the July 28 flood could not have happened in a better place. While both cities face the problems concerning urban drainage basins outlined above, the city of C olorado Springs, unlike Fort Collins, has vastly over-developed floodplains. In fact, until the flood in Fort Collins occurred, the city of Colorado Springs had no separate entity to handle the maintenance and construction of storm water facilities as Fo rt Collins does in the form of the Fort Collins Storm Water Utility. The severity of the problems facing Colorado Springs is alarming, and the rate at which changes to the city's infrastructure that would accommodate larger floods is slow. The effects o f climate and topography in El Paso County create the potential for flash flooding on Fountain and Monument Creeks, as well as their tributaries (Leon, et al. 1). In the event of a flood on the scale of the July 28 flood in Fort Collins, the city of Colo rado Springs is decidedly unprepared and radical changes need to be implemented concerning the management of floodplains in the Pikes Peak region.

It is the intent of this investigation to examine flood hazards in Colorado Springs in the context of two small, urban drainages-- Shooks Run and Douglas Creek. These were chosen for their comparability with Sprin g Creek in terms of the size of their drainage areas and because of the nature of development around these streams. These streams have been explored at length to determine what parallels and differences, if any, exist between them and the Spring Creek dr ainage in Fort Collins and to determine the readiness of the city of Colorado Springs for flooding in the context of those two drainage basins.