Rainfall monitoring systems over an urban area: the city of Rome

In small urban catchments a very high space-time rainfall resolution is needed in order to obtain with sufficient accuracy the flash flood nowcasting as well as the monitoring of sewer systems. In this light, a radar meteorology campaign was conducted during the fall of 2001, over the city of Rome (Italy), using measurements collected by the polarimetric Doppler radar Polar 55C located in the South-East of the city at a distance of 15 km from the downtown and by a network consisting of 33 tipping bucket rain gauges. A comparative analysis of the rainfall fields obtained using isohyets and geostatistic (Kriging) methods with the corresponding obtained using radar rainfall measurements was performed. The overall performance of the different methods were evaluated by using objective functions. Propagation of the errors due to the rain gauge network density was weighed changing the number of the rain gauges used to reconstruct the rainfall fields.