9. CHOICE OF ESTIMATION TECHNIQUES

The purpose ofthe study and the two main approaches to methods offloodestimation are described briefly. The choice in different circumstances ofmethods ofestimation is dissussed, with reference to the examples given in specific volumes and chapters of the Flood studies report.

The purpose of the study has been to provide methods of estimating the flood which will be exceeded on average once in T years and also the possible limit to the flood or what is described as the estimated maximum flood. Such estimates may be needed not only at sites with flow records but also at sites without records; for the latter case the methods of estimation have been developed using formulae based on catchment characteristics. Two main approaches to estimation have been developed during the study. The first was based on statistical analysis of flood series at all suitable gauging stations, and the second on the investigation of rainfall and resulting runoff at selected stations. This Paper suggests some guidelines for a choice between these two main divisions and outlines methods of flood estimation which are suitable for different circumstances.