Introduction
The growing scarcity of freshwater resources—driven by population growth and rising demand—has intensified the need for rigorous analysis and optimization of urban water distribution networks (WDNs). Flow control valves play a pivotal role in ensuring equitable water distribution across such networks. Atashparvar et al. (2019) designed and experimentally evaluated flow control valves with nominal flow rates of 5 and 10 L/s. Using dimensional analysis, they investigated the flow behavior through a cylindrical orifice and found that the actual discharge consistently fell below the design flow rate, highlighting the influence of hydraulic losses and geometric constraints.

Water extraction patterns at consumer endpoints significantly affect network performance. In residential complexes, rapid bulk withdrawal—typically for filling elevated or ground-level storage tanks—often results in transient, high-intensity demand surges. These surges induce substantial pressure drops elsewhere in the network, particularly during peak usage periods. Building upon prior research, the primary innovation of this study lies in the implementation of an automatic flow-stabilizing valve, adapted from the design principles of Bijankhan et al. (2025), to regulate maximum inflow at high-demand nodes. Critically, this approach aims to enhance upstream network pressure without altering end-user consumption behavior—achieved through the strategic sizing and deployment of flow-stabilizing valves.

Methodology
Flow measurement was conducted with two objectives: (i) to characterize the demand pattern at a selected node downstream of the water source, and (ii) to inform the design and evaluate the performance of the automatic flow-stabilizing valve. Based on a site suitability assessment and alignment with the project scope, the water supply system of Imam Khomeini International University (IKIU) was selected as the case study.

An ultrasonic flowmeter—comprising two clamp-on transducers mounted on the pump discharge pipe—was deployed to monitor instantaneous flow rates. Concurrently, an ultrasonic level sensor was custom-assembled and installed inside the main storage tank to track water volume dynamics (i.e., storage vs. drawdown phases). Data from both sensors were logged via microcontroller-based acquisition systems, with the entire instrumentation housed in a weatherproof enclosure for field deployment.

Results and Discussion
Valve performance was first validated in the hydraulic laboratory at IKIU. Prototype automatic flow-stabilizing valves were fabricated with nominal capacities of 2 and 4 L/s, respectively. These were subsequently installed on the municipal supply line feeding the university’s potable water reservoir.

All comparative analyses were conducted using operational data recorded on Sunday, 3 March 2024. Under uncontrolled inflow (baseline scenario), reservoir levels remained relatively stable. In contrast, with the 4 L/s automatic valve in operation (indicated by the blue circle in time-series plots), a progressive deficit emerged—peaking at ~3:00 PM due to sustained high demand—and reached a maximum drawdown of 40 cm by midnight, representing a 10 cm increase (from 30 cm to 40 cm) over 24 hours. The valve was activated at 12:00 PM on 3 March 2024 and remained operational until 6 March 2024. Over this 3.5-day period, the cumulative reservoir deficit stabilized at ~35 cm, equivalent to a volume loss of approximately 150,000 L.

Pipeline pressure on the municipal supply main was monitored under three conditions:

Uncontrolled inflow: Near-zero inlet pressure (~0 m), indicating gravity-driven, high-flow, low-pressure entry.
Daily flow control (4 L/s setpoint): Inlet pressure rose to ~3.6 m.
Weekly flow control (2 L/s setpoint): Pressure further increased to ~7.0 m.
Notably, these pressure gains were achieved without detectable changes in campus-wide water consumption, confirming that pressure recovery resulted solely from inflow regulation—not demand reduction.

Conclusions
Based on measured demand profiles, the peak average hourly flow rate was calculated as 3.99 L/s. Accordingly, automatic flow-stabilizing valves rated at 4 L/s (for daily control) and 2 L/s (for extended, conservative regulation) were deployed.

While the 4 L/s configuration led to a gradual reservoir deficit (~35 cm/150,000 L over 3.5 days), switching to the 2 L/s regime on Friday enabled an inflow of ~164,000 L—sufficient to fully offset the accumulated deficit. This demonstrates the system’s ability to shift inflow temporally: suppressing intake during peak periods and enabling reservoir replenishment during off-peak hours.

Critically, flow regulation alone—without infrastructure upgrades or demand-side interventions—yielded a 7-meter increase in municipal pipeline pressure (from ~0 m to 7 m) under the 2 L/s scenario. This underscores the efficacy of smart inflow management as a low-cost, high-impact strategy for improving hydraulic resilience in urban water networks.