1. Involves the use of rainfall, flood flow, or other records at a number of sites to obtain a general description of the behavior of such phenomena in an area. Regional analyses are used to improve upon the description of the distribution of rainfall or runoff that can be obtained using only the limited records available at most sites. 2. The development of general predictive models of mean rainfall or flood flows, flood flow quantiles, or other statistics, perhaps making use of physiographic information such as altitude, drainage basin area, or channel slope.