ABSTRACT
For the most part, the acquisition, preprocessing and archiving of hydrometeorological data falls outside the scope of this book. These aspects and especially the great diversity of measurement techniques (manual and automated) and methods for storing basic information (field books, analog recordings on paper, digital recordings, teletransmissions, etc.) lie within the area of basic hydrology or operational hydrology. However, to carry out a frequency analysis, it is necessary to use the available data to build a series of values corresponding to a sample in the same sense that statisticians use these terms. The construction of the series to be processed depends on the type of handling that to be carried out, or, conversely, the type of handling depends on the nature of the series of data available. In addition, for the statistical processing to be legitimate, the series under study must satisfy certain criteria. This chapter uses several examples to suggest the steps to follow to build data series. The second part is dedicated to the validation of the series of values obtained. To date, the issue of the definition of the goals of the analysis, suggested by Figure 1.2, has often been willfully ignored because it seemed so obvious. However, it cannot be stressed enough that it is extremely important to formulate the goals clearly and to adapt the steps in the analysis accordingly. In this regard, one of the essential criteria is certainly the spatial and temporal scales: studying the behavior of floods in an urban micro-watershed (with a very short concentration time) with monthly rainfall data would not make any sense! The reverse is also true: it is
useless to use rainfall data with a time step of a minute to study the Amazon watershed.
