Evaluation of rainfall network using entropy over the urban area of Rome

In many hydrological applications, rainfall data acquisition takes a great importance. Hydrological modeling accuracy is strongly dependent on the quality and quantity of the input information. This input is usually provided by raingauge networks whose density is a key parameter for proper observations of rainfall fields. The finer the space-time rainfall resolution, the higher the accuracy of the hazard nowcasting, as flash floods as well as monitoring of sewer systems. This work focuses on testing the adequacy of a high density raingauge network to cover the urban area of Rome. First, the number of the raingauges in the network is examined by evaluating the coefficient of non transferred information and the corresponding isocorrelation contours. Using the tool of informative entropy it is possible to evaluate if a certain raingauge of the network adds new information in terms of rainfall record or it has redundant information, so that it is possible to evaluate the optimum number of raingauges of the network. This method is useful not only in terms of gained accuracy of rainfall information and flood prediction, but also in terms of money savings, because redundant raingauges could be removed. Finally, a comparative analysis of the rainfall fields at different time scales is performed on the study area by grouping rainfall data according to the seasonality.