Using AHP-PROMOTHEE for selection of best Low-Impact Development designs for urban flood mitigation

In this study, in addition to studying the effects of several LID schemes on urban flood control, the Analytic Hierarchy Process-Preference Ranking Organization Method for Enrichment Evaluation (AHP-PROMETHEE) combination method has been used to select the best design. This paper investigates the drainage system in Golestan town of Semnan under a 5-year return period. The LID methods have been selected based on the region's conditions and available facilities. Then Rain Barrel (RB), Permeable Pavement (PP), and Infiltration Trench (IT) were considered as LID methods. Seven scenarios with the names RB, PP, IT, IT-PP, IT-RB, PP-RB, and IT-PP-RB have been considered to provide the best LID usage combination. Four analytical ranking criteria were selected for the ranking procedure, including implementation cost, hydraulic performance, environmental impact during implementation, and ease of implementation. Then the weight of these criteria was obtained using Analytic Hierarchy Process (AHP). Finally, after determining the weight criteria, the LID designs were ranked using the Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) method. The results of hydraulic studies indicate the effectiveness of the PP-RB scenario with an average reduction of 90% of peak discharge and an average reduction of 80% of total flood volume. Also, the weakest performance is related to the IT scenario, with an average decrease of 60% of peak flow and 47% of total flow volume. AHP-PROMETHEE analysis showed that the simultaneous use of RB and IT with a coverage percentage of 5% and a cost of $ 57,710 reduced the total volume by 51.54% and the peak discharge by 48.8% compared to the results of the current system. According to AHP-PROMETHEE, IT-RB-5 is the best project proposed among the 70 projects studied. This study showed that the AHP-PROMETHEE method could be used as a practical method to choose from several LID schemes for flood control.