Author(s): Alexandros Mentes; Panagiota Galiatsatou; Panagiota Stournara; Dimitrios Spyrou

Linked Author(s): Panagiota Galiatsatou

Keywords: Hydraulic modeling; Emergency scenarios; Intermittent water supply

Abstract: The present work aims at developing and simulating emergency water supply scenarios for Thessaloniki city in Greece, to respond to a major failure occurring in one of the city’s central aqueducts. The methodology developed includes: i) water demand estimation in the city’s tank zones, ii) hydraulic simulation of the city’s aqueducts under normal operating conditions and c) formulation of intermittent water supply schedules in the entire conurbation of Thessaloniki, considering a major failure occurring in Aravissos aqueduct (water supply from Aravissos springs and water supply boreholes). To estimate mean water demand in all tank zones of the city, both theoretical and measured data are considered. The theoretical estimation of water demand relies upon using population data, as well as on specific water consumption data of the different urban planning units. Final estimates of water demand in each tank zone are assessed by also considering available information from the existing Supervisory Control and Data Acquisition (SCADA) system of the Water Supply and Sewerage Company of Thessaloniki (EYATH S.A.). Hydraulic modeling of Thessaloniki’s aqueducts is performed using Bentley OpenFlows WaterGEMS software. The hydraulic model for normal operating conditions of the system is calibrated using available data from EYATH S.A.’s existing SCADA system, such as water level data in some of the system’s tanks, and reliable pressure and flow measurements downstream of a number of pumping stations. Calibration of the system’s hydraulic model is performed manually considering an extended period simulation (EPS) for an entire typical day. Three alternative emergency scenarios of water supply are then formulated relating with failure occurring in Aravissos aqueduct. These scenarios are formed to confront with: (a) a basic failure scenario at Aravissos aqueduct, cutting off water supply from Aravissos springs, (b) a scenario similar to (a), interrupting water supply of the industrial area of Thessaloniki after verifying the failure, and (c) a scenario similar to (a), activating an existing interconnection between the city’s aqueducts (aqueducts of Aravissos and Aliakmonas). Hydraulic simulations for all emergency scenarios verify that the main objectives set for managing such adverse conditions in the city of Thessaloniki are satisfactorily met. However, it becomes quite evident that it is not always possible to strictly comply with the designed intermittent water supply schedules. It should also be noted that considering an interconnection of the city’s aqueducts, significantly improves the system’s response to a major failure in the aqueduct of Aravissos.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022183

Year: 2022