ABSTRACT
Magnitude/frequency studies are of vital importance in hydrological analysis; they also are fundamental to many areas of flood hazard research and the economic evaluation of flood alleviation schemes. Methods of flood routing have been developed further in studies at the Hydraulics Research Station. Systems for mathematically modelling river flows have been developed, many of which result from advances in computer use. Hydrographs are then used to convolute the rainfall into runoff hydrographs for the main streams and the tributaries. Data on soil characteristics and fluctuations in the water table are central to the analysis of waterlogging. Land-drainage surveys have also systematically identified the location of flood hazards and land drainage problem sites following the requirements for these surveys under Section 24(5) of the Water Act 1973. Dissatisfaction with the rational formula has led to revised methods for the analysis and design of urban storm drainage sewer systems.
