Risk Analysis in Development of Reconstruction and Rehabilitation Programs of Urban Water Infrastructures

Due to high growth rate of large cities, in reconstruction and rehabilitation of urban water infrastructures, new demands of the system should be considered. Different possible scenarios are defined to deal with these increasing demands and are tested to find the appropriate one with the least risk. In evaluating risk of these scenarios application, the performance of system under their application is considered. The system performance is quantified in its planned period of operation. In this study a small water distribution network is considered as the case study. Different rehabilitation and reconstruction practices are defined for this system and system performance under these scenarios is evaluated. Then the acceptable risk of water supply with adequate quantity, quality and pressure based on the water demand type is determined and the scenarios are compared with the defined thresholds. The scenarios that pass this step are considered for cost-benefit evaluation to find the optimal solution. The system performance under application of selected scenario is evaluated in its operation period. This will help to find the most practical solutions in infrastructures improvement and avoid from starting projects with high risks that are common especially in developing countries and usually are left incomplete.