Advanced Zoning Methods (District Metered Areas)
Introduction
The conventional zoning methods are limited to manual identification of manageable command areas with similar attributes like pressure, nodal heads or sometimes the administrative boundaries are also used to identify suitable zones.
However these kind of approaches do not ensure the hydraulic reliability of water networks and the ease of operation and maintenance. As the complexity of water networks increased, the water utilities realized the need of partitioning the water networks into suitable zones.
These zones (sectors, clusters or district metered areas are used alternatively now a days) have become one of the efficient strategies of managing water networks. It was first introduced in the United Kingdom in 1980s and has been adopted across the globe.
The advanced zoning strategies not only ensure better operation in terms of leakage reduction but also promote the preventive maintenance and water quality and protection against contamination in the water networks. We will discuss all the modern methodologies of zones identification and will demonstrate how to successfully identify reliable zones in EPANET software in a programming environment.
There are many aspects which affect the identification of zones. (Here onwards we will use District Metered Areas or DMAs instead of zones). Basically it involves identification of boundaries of zones and closure of a few boundary pipes between the two zones and installing flow measuring devices in pipes which are kept open. The following figure highlights the DMAs and their boundaries in a given water network.
Every water network is unique in its topology, size and characteristics. Hence there is no standard procedure available for identification of DMAs but a series of guidelines provided by different water utilities. The most popularly used in the research community is IWA guidelines (Morrison 2007).
Factors affecting the DMA Design/ Design of Zones
As per the IWA guidelines, the following points should be considered while identifying the DMAs in a given water network.
· Infrastructure condition (leakage levels, availability of pressure at each node)
· Size of the network (number of customers served)
· Types of customers (residential, institutional, industrial, commercial)
· Ground elevation
· Water quality considerations
· Pressure requirements and firefighting capacity
Number of valves and flow meters required for implementing the strategy (Cost aspect)
In the next chapter we will discuss the general steps or work flow chart for identification of DMAs.
Activity: What is the recommended size of each DMA as per the IWA guidelines for DMA establishment? (Hint: refer to the IWA guidelines.)
References
[1] Morrison J, Tooms S, Rogers D (2007) DMA management guidance notes. IWA Publication
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