Elisa Oliveri

Estimation of urban structural flood damages: the case study of Palermo

Abstract The estimation of flood damage is a fundamental step in the economic analysis of a flood control projects. In particular, frequency–damage functions, derived from the hydrologic, hydraulic and damage relationships, are one of the fundamental pieces of information upon which expenditure decisions are based. The aim of this study has been to develop an empirical frequency–damage relationship, obtained by means of detailed local studies, which could be a judgement tool for flood mitigation measures in strongly urbanised drainage areas. Monuments and other estates having a cultural or artistic significance have been specifically taken into account. The analysis has been carried out for the urban area of Palermo (Italy). Damage has been calculated as a percentage of damaged property value, depending on water depth. The structural replacement cost has been used to estimate the average value of a property. Technical and economic efficiency of various flood mitigation measures can be assessed comparing related frequency–damage relationships.

Mitigation of urban flooding: A simplified approach for distributed stormwater management practices selection and planning

The urbanization process and the hydraulic insufficiency of drainage systems are two of the most common causes of urban flooding. In some technical regulations, distributed stormwater management practices (DSMPs) are regarded as a solution for urban flooding problems. They can prevent the formation of runoff, dispose of it locally, or dampen its peak before it reaches the drainage system. Due to their diffuse localization and the wide number of available solutions, the evaluation of their efficiency in terms of flood reduction is very difficult. The methodology proposed in the present paper relies on the concept that the mitigation effects of DSMPs can be expressed as a function of the changes of the hydrological parameters of a catchment. Once the relation between a DSMP and the equivalent hydrological parameter is established, the efficiency of DSMPs can be evaluated using mathematical models simulating the runoff formation and propagation in urban areas and applying methodologies similar to parameter sensitivity analysis and model uncertainty propagation. Studying the effect of parameter variation on model output, it is possible to analyse quickly several different stormwater management solutions and to identify the best distribution of measures in order to achieve a defined mitigation task. The simplified procedure has been compared with a more detailed approach obtained by fully integrate DSMPs in the drainage system hydrodynamic model. The procedure has been applied to the real case study of Mondello catchment in Palermo (Italy), and the analysis of the results allows the identification of some guidelines for the mitigation plan preparation.

Urban Drainage And Sustainable Cities:How To Achieve Flood Resilient Societies?

This paper tries to describe the main developments of urban flood forecasting and modelling. Currently, several new technologies are available for flood monitoring, modelling and mitigation and several paradigms suggest the adoption of greener approaches to urban storm water management. These tools and new approaches can be easily adaptable to new developments where the entire urban drainage system can be suited to follow a more sustainable way to drain storm water. The challenge for the future is instead aimed to apply this new philosophy to existing urban areas where the application of new tools and technologies requires high costs and such approaches have to be prepared by constructing a flood resilient society by means of education and capillary information.