The objective of frequency analysis in a hydrologic context is to infer the probability that various size events will be exceeded or not exceeded from a given sample of recorded events. Two basic problems exist for most hydrologic applications. First the sample is usually small, by statistical standards, resulting in uncertainty as to the true probability. And secondly, a single theoretical frequency distribution does not always fit a particular data-type equally well in all applications. This manual provides guidance in fitting frequency distributions and construction of confidence limits. Techniques are presented which can possibly reduce the errors caused by small sample sizes. Also, some types of data are noted which usually do not fit any theoretical distributions.

The report is basically a source book for individuals who are actually concerned with the problem of constructing alternative plans for developing urban areas. It reviews the methods and computer models that are currently available to the planner or engineer for developing water and related land resources. These reviews discuss the availability and usefulness of several models; give a brief technical description of each model, including the input data required; and indicate the amount and type of computer hardware needed to use each model. The report is directed mainly toward water related problems. Thus, most of the methods discussed deal with urban drainage, wastewater management, flood routing, reservoir operation, water supply, flood zoning, and the social and economic aspects associated with these areas. (Modified author abstract).