This paper presents a comparative analysis between rain-gauge storm tracking techniques in order to achievea better knowledge of the rainfall dynamics over an urbanized area. The temporal and spatial distribution andkinematics of short term rainfall are recognized as one of the most important reasons in error production inrainfall-runoff on urban catchments. The uncertainty due to rainfall variability can greatly affect urban drainagemodeling performance and reliability thus reducing the confidence of operators in their results. Modelingrepresentations of urban catchments and drainage systems are commonly adopted for surface flooding forecastingand management and an adequate knowledge of rainfall spatial and temporal variability should beconsidered as a fundamental step for a robust interpretation of the physical processes that take part in urbanareas during intense rainfall events. The starting basis of such studies is usually given by a network of highresolution raingauges disseminated inside and around the examined urban area. One of the raingauge techniquesused is based on simulating the storm motion by visualizing the sequence of the rainfall patterns obtainedusing rain-gauge data and on spatial correlation. The storm speed and direction are obtained using therain-gauge method by tracking the advance of the maximum rainfall intensity in time and space. A secondmethod is based on the identification, for each gauge, of the time of occurrence of some significant featuressuch the time of onset of a storm or the time of peak. A third method is based on the classical idea of spacetimeautocorrelation function; This function describes the way in which the correspondence between therainfall patterns at two points in space-time reduces as the distance between two points is increased.The analysis has been carried out on the basis given by high resolution rainfall data collected over Palermourban area (Italy). The urban area has a surface of around 30 km2 and it is mainly distributed on North West– South East direction. The monitoring network is made of 10 tipping bucket raingauges. Bucket volume isequivalent to 0.1 mm rainfall.Raingauges have been uniformly distributed over the urban areas allocating them mainly over public buildingsand school in order to allow for easy access. The network has been put in place in January 2006 and it isstill working. Data is monthly collected by the operator that also provide for clock synchronization and ordinarymaintenance and cleaning.An accurate analysis of the results of this comparison between the techniques has been carried out and, sincethe city of Palermo is not covered by any meteorological radar, the analysis of storm dynamics will allow tocreate a system monitoring hydrometeorological conditions which operates on time basis using the informationcoming from the raingauge network as forecast triggers.
|Numero di pagine||6|
|Stato di pubblicazione||Published - 2009|