Identifying Urban Flash Flooding Problems

The focus of flood control activities in urban areas has been the alleviation of problems associated with major river flooding. Meanwhile, unplanned urban development has caused flash flooding problems of small streams to worsen, and eventually to receive priority attention. Because of limited resources, flood control agencies must choose individual streams for immediate attention, while deferring flood control action on others. Very little direct information exists upon which to base an evaluation of the relative flash flooding problems of individual streams. A methodology, based on multiple discriminant analysis, is presented to provide a decision-making tool to establish flash-flood control priorities among a number of urban streams. The analysis is based on indirect measures of flash flooding problems (land-use characteristics of the watershed, stream configuration, etc.) that are readily available to the flood control agency, instead of flood damages inventories and hydrologic data, which are often unobtainable. Using the discriminant models, individual streams can be singled out for priority action.