Study of Modifying Design Discharge of Water Distribution Systems From Max.hour to Max.day
Dr. Eng. Jihad Saba
The design and analysis of drinking water distribution systems rely on several design parameters, including design discharge, which codes and references adopt as the maximum hourly discharge in the target year. However, following the performance of many drinking water distribution systems in Syria—especially daily and hourly discharges and consumption patterns—it has become evident that there is no single maximum consumption hour. Instead, peak consumption extends over a period of several hours with values lower than the maximum hourly consumption in the target year upon which systems are designed. That is, consumption values, patterns, and charts change as dictated by water scarcity conditions. Technically and economically, network design heavily relies on the designer's experience in making an accurate and realistic selection of the design discharge for the entire system, as well as accurately predicting loads or withdrawals at system nodes. To achieve an acceptable estimation of design discharge and withdrawal quantities, studies on continuous water distribution systems have relied on the geometric method for population forecasting, rather than adopting a method suitable for the reality and nature of population growth in the study area. Under water scarcity conditions, studies on intermittent water distribution systems rely on field measurements and computer models that differ from continuous flow models due to the multiplicity and overlap of influencing factors. Selecting the design discharge under water scarcity conditions fundamentally depends on the designer's experience, particularly under intermittent supply conditions. Therefore, work is underway to develop mathematical tools and simulation models to estimate future withdrawals, helping designers accurately predict water needs and design discharge. These models are built—after identifying the influencing factors and determining the contribution of each factor—using various techniques, including Regression and Artificial Intelligence (AI). Determining node withdrawals under intermittent supply conditions—which is prevalent in Syria—with varying pressure conditions and the presence of building tanks and pumps, holds special importance in the study of drinking water systems under intermittent supply. The research concluded that for a better technical and economic design, it is preferable to select either the maximum daily discharge or the average daily discharge during peak summer months as the design discharge. It is also preferable to design drinking water networks in phases, with necessary calibration, making the design realistic and technically and economically viable.