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Design of water supply systems: Fundamentals and a brief overview

29.04.2022.

Water supply systems are one of the most important infrastructure buildings. The main purpose of water supply systems is the distribution of water to all its users. Water must be delivered in sufficient quantity and at acceptable pressure.

Requirements such as environmental protection, conservation of natural resources, and cost-effectiveness of the system set additional conditions in the design, construction, and maintenance of water supply systems.

GRAVITATIONAL AND PRESSURE WATER SUPPLY SYSTEMS

Water supply systems can be divided into two basic groups based on their functioning – gravitational and pressure systems.

In a gravitational system, if terrain conditions allow, water is distributed from the reservoir, which is located at a sufficient height, to the distribution area.

The pressure system uses pumps that provide sufficient water and pressure for distribution. Usually, the water system consists of both gravitational and pressure parts. Considering maintenance costs, gravitational systems are more acceptable.

TOPOLOGY OF WATER SUPPLY SYSTEM

Considering the topology of the water supply system, we distinguish between branched and annular networks.

The branched network distributes water through one or more distribution lines that end at certain points.

An annular network allows water to be delivered to a point from multiple directions.

Often water supply systems consist of both annular and branched parts. The problem with the branched network is the small flow of water (which includes a lower flow rate) at the ends of the branches.

PURPOSE OF DESIGN

In addition to standard water consumption for industry and households, water supply systems must be designed to meet fire protection requirements.

These requirements can significantly increase the cost of building and maintenance of water supply systems.

Standard procedures and types of projects apply to the design of water supply systems as well as to other buildings.

The project documentation can be in the form of a conceptual solution, conceptual design, main and implementation project.

For each type of project, the concept, content, and detail are defined.

WHAT DOES THE DESIGN OF WATER SUPPLY SYSTEMS DEPEND ON?

The design of water supply systems significantly depends on spatial characteristics.

This includes topography and its influence on the pressure distribution in the pipe network.

Land use and ownership affect construction costs, while soil spatial characteristics affect excavation costs.

Most water supply systems are installed on existing or planned roads, so problems with existing communal infrastructures can occur during construction.

All this greatly affects the layout of the pipeline route and the appearance of the network.

COMPLEXITY OF WATER SUPPLY SYSTEMS

Water supply systems are complex in themselves because they cover a large area. 

They usually consist of multiple pipe loops, are regulated by nonlinear hydraulic equations, and contain complex hydraulic devices such as valves and pumps. 

They are affected by energy requirements due to draining and the trade-off between initial investment and operating and maintenance costs during the project period.

In accordance with the project water supply quantities and characteristics of the water supply network (material, location, and mode of operation of facilities on the network, topographic conditions) it is always necessary to hydraulically dimension the water supply network so that it meets the required water supply quantities and pressures.

Even with the use of simulation models, designers are still faced with a difficult task. One of the most commonly used software for hydraulic calculations and modelling of water supply systems is the software EPANET, developed by the US Environmental Protection Agency EPA.

Many software, including StudioARS Urbano Hydra, rely on EPANET for this purpose.

During the design and construction of the water supply network, it is necessary to overcome frequent changes in the direction, diameter, and type of joints, and to perform branching of pipelines. This is solved by using fittings.

The water supply network also contains plumbing fixtures – various devices that serve for its proper functioning, management, and maintenance, such as valves, underground and aboveground hydrants, air valves and sludge outlets, check valves, etc.

The water supply network is presented in the project by the situational plan, longitudinal profiles of the pipeline, characteristic cross-sections of the pipeline, details, and schemes of nodes.

Node diagrams contain a schematic representation of nodes with fittings and plumbing fittings and a tabular representation of the required elements in each node.

3D MODELS OF PIPE INFRASTRUCTURES

Recently, there has been a growing need for a 3D model of pipe infrastructures, including water supply systems. BIM (Building Information Modeling), among other things, requires the existence of a detailed 3D model.

The 3D BIM model is used to coordinate the project, which can identify shortcomings in the project and possible collisions with other pipe infrastructures or other solid structures. By timely detecting problems and intervention in the design phase, it is possible to significantly reduce project costs and prevent violation of deadlines.

Modern software such as StudioARS Urbano can meet many of these requirements that water supply system designers need.