Time resolution of rain gauge data and its hydrological role

Collected rainfall records by gauges lead to key forcing in most hydrological studies. Depending on sensor type and recording system, such data are characterized by different time-resolutions, ta. In this chapter, first a temporal evolution of ta is presented on the basis of a large rainfall database of rain gauge networks operative in many geographic areas, then the role of a non-homogeneous temporal resolution of rain gauge data in the analysis of historical series is discussed with the aim of avoiding possible errors in hydrological investigations. Particular emphasis is given to the possible effects of using different ta on the determination of extreme rainfalls that have a crucial role in the design of hydraulic structures. Simple equations for improving the estimate of these rainfalls are also described. Finally, a representative investigation of the problems is performed using data available in the Umbria region (central Italy).