No abstract

The polluting effects of storm water runoff on the receiving waterbodies represent an increasingly relevant problem in developing urban areas. In combined sewer pipes, transiting flood waves cause the alternation of sediment erosion and deposition of the solid material transported by the flow. Combined sewer deposit, mainly generated as an effect of such phenomena during the dry weather period between two rain events, is generally a mix of sand and highly polluting materials. Accumulation of sediments along a combined sewer network is often the cause of dysfunctions in the drainage system itself and negative impacts on the quality of receiving waters, due to the resuspension and overflow of pollutants. Both aspects have been investigated for the combined sewer of Rome thanks to an experimental catchment of about 2800 ha in the Cesarina -S. Basilio area. Based on the simulations conducted, structural solutions were proposed and evaluated, aimed at reducing the operational and environmental problems related to sewer sediment. The results show noticeable margins for the optimisation of the whole sewer system and for the reduction of its environmental impact.

Increasing urbanisation and intensification of human activities are common trends all over the world. The higher portion of impermeable urban surfaces often leads to well known effects on storm water runoff and its polluting potential for receiving waters. Despite the variety of structural solutions and management practices proposed to mitigate the operational and environmental impact of urban runoff, their application on existing drainage systems can often be either ineffective at a metropolitan scale or unfeasible for a densely urbanised territory. Among all the proposed alternatives, the real time control (RTC) of drainage systems is proving more and more promising to dynamically regulate the system capacity in response to intense rainfall. The combined sewer network of Rome, historically built with high-capacity pipes to collect storm water from both urban and natural catchments, holds significant potential for RTC of online storage and combined sewer overflows, to optimise the global drainage capacity and reduce the impact of discharges on local river quality. To assess the real benefits, the potential limits and the feasibility of such a system for the city sewers, a pilot study has been conducted on a 3,000 hectare sub-catchment. It involved the development of a fast-response hydrodynamic simulation tool for the sewer network, the definition and evaluation of RTC strategies and the implementation of an environmental integrated telemetry system. As described here, the study has highlighted significant margins for the optimisation of the global network capacity without any major interventions on the physical assets, as well as some critical issues to solve for a fully operational RTC application.

This paper develops a model to characterize the demand for domestic water based on its end users' usage habits. The use of individual residential appliances (bathroom sink, toilet, shower, bath, etc.) is interpreted using a probabilistic approach. The paper also applies the model to the distribution network of the municipality of Sparanise, a small city in the province of Caserta, Italy. The results of this application are compared to the real output of the city's actual water reservoir. Flow variability during the day was successfully modelled. A comparison of the simulated and recorded data on a daily level indicates the proper adjustment of the volume distribution; the peak flow rates were also comparable. The model could be a useful tool for analyzing domestic water consumption, especially in the design and management of water distribution networks. Use of the model would particularly aid the Integrated Urban Water Management Operator both in optimizing the operating pressures in the various districts’ networks and in predicting domestic water consumption when drafting its water balance documents.