Development of a methodological framework to calibrate and validate a hydrodynamic model of the sewer system of a pilot basin. Case study: Quito, Ecuador

Urban Drainage Systems (UDSs) have existed since the Babylonian Empire. Their objective is to preserve and promote public health, welfare, and flood protection and avoid water pollution. Population and urbanization growth, climatic change, and aging structures are the main factors to produce failures in sewer systems due to the increase in surface runoff induced by changes in land use and land cover. The consequence is urban flood hazards. Therefore, in this research, a methodologic framework was developed to assess the hydraulic performance of a UDS in a pilot basin situated in Quito, Ecuador. By using three kinds of information, spatial, temporal, and terrain, a number of products were generated, such as design rainfall, historical precipitation, dry weather flows and their patterns, a topological network, land uses, a DTM, a DSM, and an orthophoto, and subsequently, a hydrodynamic 1D model was built by using a PCSWMM model. Calibration and validation of the model was carried out by employing hydrometeorological data that were registered in ultrasonic sensors to measure the depth and velocity of the flow every minute and a gauge station, which were implemented in the study area from January to October 2023. To evaluate the goodness of fit, the ISE, NSE, R2, LSE, and RMSE were employed, whose values were within the recommend ranges. The results of this framework could provide support to decision makers to come up with the optimal rehabilitation measures, which could be gray, green, or hybrid,with a combination of these infrastructures, to minimize flood risk and improve the level of service of this important sanitary infrastructure.