investigation the hydraulic performance of a part of the storm sewer network of ramadi city

Abstract

High rainfall intensity, which has occurred in Iraq during the last few years, is considered as part of the natural hazards that affect and damage the infrastructures, such as the road networks of the urban cities. The poorly designed Storm Sewer Networks (SSN) with low intensity, as well as the neglect of the maintenance caused that the pumping stations do not cope with the unexpected increase of the rainfall intensity which happens during some consecutive days in winter season. As shown in this study, the increase in the designed rainfall intensity to three times led to an increase in the overflow risk by 43%. This study suggested many scenarios to treat the most affected areas by increasing the efficiency of Ramadi SSN. Specifically, by adding a pipeline in Al-Shurta zone and other pipes to link the collateral lines in Al-Andalus and Alhoz zones to reduce the overflow damage as this method reduced the percentage of overflowing to 32%. Storm Water Management Model (SWMM) was used to evaluate the SSN in Ramadi City and depending on design rainfall intensity. The rainfall intensity was increased two to three times because of the absence of metrological stations in the study area to record rainfall intensity data of the rain storm. The model outputs were analyzed to evaluate the possible changes in the rainfall discharge of the SSN during the possible scenarios of the increased rainfall intensity. Moreover, Expanding Cost Ratio (ECR) were suggested to evaluate the cost of the network development. The longitudinal index ( which represents the total cost of the added pipes to the length of the main pipe, and the area index ( which represents the total cost of the added pipes to the total area of the zone. The value of the longitudinal index ranged between 47 to 57 US dollars/m, and the area index was 178 dollars/hectare.