⚡ electrical engineering

Hydraulic Modelling of Water Distribution System in Response to Different Scenarios: A Case of Adigrat Town, Ethiopia

This study utilizes hydraulic modeling with Bentley WaterGEMS to diagnose pressure and velocity deficiencies in Adigrat Town's water distribution system, demonstrating that targeted infrastructure upgrades and pressure management strategies effectively restore service reliability to meet design criteria.

Original authors: Kiros Aregawi, Beshah Megosse

Published 2026-07-30

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CC BY 4.0

Original authors: Kiros Aregawi, Beshah Megosse

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine a city's water supply system as a giant, invisible circulatory system, much like the veins and arteries in a human body. Just as your heart pumps blood to every finger and toe, a water utility pumps liquid gold through a sprawling maze of pipes to every home, school, and shop. But unlike your body, which heals itself, these pipes are old, often buried underground, and constantly stressed by the city's growing population. When the demand spikes—like during a hot summer evening when everyone turns on their taps—the system can get clogged, pressure can drop, or pipes can burst. This is the world of hydraulic modeling, a branch of engineering that uses powerful computer simulations to act like a "digital twin" of a real water network. Engineers feed data about pipe sizes, elevations, and water usage into software to see how the system behaves under stress, allowing them to spot trouble spots before they turn into dry faucets or flooded streets.

In this study, researchers Kiros Aregawi and Dr. Beshah Megosse took a close look at the water distribution system in Adigrat Town, Ethiopia. They treated the town's network like a complex puzzle, using a sophisticated software called WaterGEMS to build a virtual replica of the real pipes. Their goal was to see how the system held up under different scenarios, particularly when the town's population was growing fast and water demand was high. They didn't just guess; they calibrated their digital model using real pressure readings taken from five specific spots in the town, ensuring their computer simulation matched reality with high precision. The results revealed that the existing system was struggling: during peak times, over a third of the connection points (nodes) didn't have enough pressure to push water up to homes, and nearly a fifth of the pipes were either flowing too slowly (risking sediment buildup) or too fast (risking damage). Furthermore, the system was losing nearly 29% of its water to leaks and other inefficiencies. However, the study didn't just point out the problems; it simulated a "fix-it" scenario. By virtually upgrading pipe sizes and installing pressure-regulating valves, the researchers showed that the network could be optimized to meet safety standards without needing to be completely replaced, proving that smart, targeted upgrades can breathe new life into an aging water grid.

Technical Summary: Hydraulic Modelling of Water Distribution System in Response to Different Scenarios: A Case of Adigrat Town, Ethiopia

Problem Statement
The water distribution system (WDS) in Adigrat Town, Ethiopia, faces critical challenges driven by rapid urbanization, uncontrolled population growth, and ageing infrastructure. The existing system, originally designed with specific assumptions, is increasingly unable to meet rising water demands, leading to persistent supply shortages and reduced service reliability. Key issues include inadequate pressure levels, inefficient operational practices, and significant non-revenue water losses. Furthermore, previous assessments have largely relied on single-demand scenarios, failing to capture the hydraulic variability under different operating conditions. The lack of a comprehensive, scenario-based hydraulic evaluation hinders the development of effective rehabilitation and management strategies for this rapidly growing urban area.

Methodology
This study employed hydraulic modelling using Bentley WaterGEMS V8i software to evaluate the existing WDS under varying demand scenarios. The methodology followed a structured workflow:

Data Collection and Preparation: The research utilized GIS-based network data, field observations, and operational records (July 2017–June 2018) from the Adigrat Town Water Supply and Sewerage Service office. Data included pipe characteristics (material, diameter), junction elevations, reservoir levels, and pump definitions. Population projections were calculated using the Central Statistical Agency (CSA) method with a 4.18% annual growth rate.
Model Development and Calibration: A hydraulic model was constructed by overlaying land use maps with the network layout. The model was calibrated against field pressure measurements taken at five representative junctions across low, medium, and high-pressure zones. Calibration performance was assessed using the coefficient of determination ( $R^2$ ) and the degree of accuracy (pressure error).
Scenario Analysis: The study simulated the system under average daily demand and peak hourly demand conditions. Key hydraulic parameters, including pressure, flow velocity, and head loss, were analyzed against standard design criteria (e.g., minimum pressure of 10–20m, maximum pressure of 70m, and velocity limits of 0.3–3.0 m/s).
Optimization: To address identified deficiencies, the Darwin Designer optimization tool within WaterGEMS was utilized to evaluate improvement alternatives, specifically focusing on pipe diameter upgrades and the installation of Pressure Reducing Valves (PRVs).

Key Results
The hydraulic analysis revealed significant performance gaps in the existing Adigrat WDS:

System Losses: The system exhibited a total water loss of 28.8%, attributed to physical leakage and apparent losses such as meter inaccuracies and unauthorized use.
Pressure Deficiencies: During peak demand hours, 37.41% (107 out of 286) of the network junctions failed to meet minimum pressure requirements. Conversely, during low consumption hours, 14.34% of junctions experienced excessive pressure (>70m), particularly in areas with complex topography and poor original design.
Velocity Issues: Under peak demand, 20.16% of the 352 pipes operated outside recommended velocity limits. While 0.28% exceeded the maximum limit of 3.0 m/s, a significant portion (19.88%) operated below the minimum of 0.30 m/s, posing risks of sediment deposition and water quality degradation.
Calibration Accuracy: The model demonstrated high reliability, achieving a coefficient of determination ( $R^2$ ) of 0.9897 between observed and simulated pressures. The average pressure error was -1.45m, falling within the acceptable range of ±1.5m for good data sets.
Supply-Demand Gap: A quantitative analysis indicated a daily supply deficit of approximately 2,265 m³/day between the current production capacity (3,845.7 m³/day) and the projected total average daily demand (6,111.02 m³/day) for 2018.

Significance and Contributions
The paper posits that hydraulic modelling serves as a critical decision-support tool for urban water utilities facing rapid growth and infrastructure stress. By moving beyond single-scenario assessments, this study provides a robust technical basis for understanding system behavior under dynamic conditions.

The primary contribution is the identification of specific hydraulic deficiencies—namely pressure shortfalls and velocity anomalies—that compromise service reliability. The study demonstrates that targeted rehabilitation measures, such as pipe diameter optimization and pressure management via PRVs, can significantly enhance system performance without necessitating a complete network replacement. The findings offer a practical framework for water utilities to prioritize infrastructure investments and improve operational efficiency, thereby supporting the sustainability of water supply services in rapidly expanding Ethiopian towns.

Limitations
The authors acknowledge that the study was limited to hydraulic performance and did not incorporate water quality analysis, specific leakage localization, pipe deterioration rates, energy consumption metrics, or future climate change impacts. Additionally, model calibration was constrained by the availability of pressure gauges, limiting the number of calibration points to five junctions. Future research is recommended to integrate these factors for a more comprehensive system assessment.

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