A simplified framework for water supply system planning and operation under deep uncertainty

Código

I-EBHE0189

Autores

José Luís Polygacz de Nazareno, Conceição de Maria Albuquerque Alves

Tema

WG 2.6: Water systems analysis for integrated planning & management

Resumo

Decisions and planning for water systems are impacted by the unpredictability of future events. Water treatment companies need relatively quick and adaptable ways to adopt policies for operating water supply system supplying water to different service areas. This study developed a structured, easy-to-understand methodology for evaluating different supply conditions in service areas. Using the Water Evaluation And Planning System (WEAP) platform and incorporating deep uncertainty procedures, various configurations of water operation and distribution were assessed by defining specific performance objectives for the water system. This study evaluated three different supply conditions for the Federal District of Brazil from 2021 to 2060. For each of these conditions, factors of deep uncertainty were varied across ranges to broadly account for future states of the world (SOW). These factors included the demand growth, varying from 1% to 2% per year and the reduction in real losses, between 0% and 10%. Thus, for each supply condition, 36 scenarios were generated, amounting 108 possible operating conditions. Additionally, with the insertion of 1000 synthetic series of inflow and evaporation, representing variations in climatic conditions, each of these scenarios can be evaluated 1000 times, totaling 108,000 simulations of future possibilities. The behavior of the adopted operational conditions was evaluated for the 40 years of simulation. Three indicators were created for assessment: the annual percentage of unmet demand in service areas, representing the severity of service failures; the total electric energy consumption used in the production at each water treatment plant during the simulated period; and the number of monthly failures in accumulation reservoirs. Through a multi-objective approach using these three indicators, the behavior of the three supply conditions was evaluated. By establishing the average of these indicators as limits for selecting simulations, the supply condition 3 seemed to present the best performance. On the other hand, if the primary factor is minimizing the severity of service failures to meet consumer demand, supply condition 2 is a better alternative of system configuration. The methodology demonstrated flexibility in dealing with future uncertainties, allowing for the selection of the condition that best met the objectives and priorities of the water utility by choosing specific indicators.