A Layered View of Smart Water Networks
There is more to water distribution than pipes and valves. Today’s water networks are becoming smarter, with utilities managing an increasing flow of data, and not just water. When discussing the “Smart Water Network”, which we take to be the entire system of data technologies connected to or serving the water distribution network, it is informative to separate its components into layers.
Just as communications protocols or computer systems may be described as layers with distinct functions, with interaction typically occurring between adjacent layers, the following layer model should help guide a meaningful discussion of water and wastewater network data systems.
The physical layer is comprised, as its name suggests, of the physical elements enabling the distribution and delivery of water along the network. Generally speaking, these are the “wet” components which deal only with drinking water, stormwater, or wastewater.
Pipes, pumps, valves, pressure reducing valves (PRVs), reservoirs and delivery endpoints are all part of the physical layer. These are data-less elements, that typically perform mechanical, hydraulic or chemical functions. While the physical layer does not have data interfaces, it can be controlled using data collected in the next layer – sensing and control. Although there may be valuable innovation and design in this layer, any system which is purely focused on the physical layer is not a part of the data technologies of the Smart Water Network.
The sensing and control layer is comprised of equipment and sensors that measure parameters of the water delivery and distribution (such as flow, pressure, water quality parameters, reservoir levels, water temperature, acoustic information and more) and remote-controlled devices enabling to remotely operate the network (such as remote-controllable pumps, valves, and pressure-reducers).
In essence, the sensing and control layer is the only interface between the network operator’s data systems on one side, and the physical layer on the other side, enabling the connection of the “smarts” of the Smart Water Network to the real, physical network. Elements of this layer typically have one “wet” end or aspect with direct contact or relation to water (such as a valve or the mechanical end of a flow sensor), and one “dry” data interface (such as a valve controller input, or a sensor’s data output).
The collection and communications layer is responsible for discrete data point collection, transmission, and storage. By using two-way communication channels, commands are then given back to the second layer to instruct sensors and actuators about what data to collect or which actions to execute. For example, a fixed cable network, radio, cellular, Wi-Fi, and other communication technologies related to data transfer are all part of this layer.
This is the first “dry” layer, as it only moves data between the sensing and control layer and the higher layers. The data management and display layer is where data from different sources comes together and may be used by operators. It may be pre-processed, stored, transferred, and accessed by central systems. Similarly, this is where human operator commands or instructions from higher-level systems are interpreted into concrete device settings (e.g. changing to a named network configuration may imply switching several pumps on or off, changing valve states, etc.). This interfaces with the underlying communications infrastructure on one side, and with a human operator or with other central data systems on the other side.
The data management and display layer is where data from different sources comes together and may be used by operators. It may be pre-processed, stored, transferred, and accessed by central systems. Similarly, this is where human operator commands or instructions from higher-level systems are interpreted into concrete device settings (e.g. changing to a named network configuration may imply switching several pumps on or off, changing valve states, etc.). This interfaces with the underlying communications infrastructure on one side, and with a human operator or with other central data systems on the other side.
The dashboard applications provided with many SCADA systems (or developed in-house at various water utilities) often fall into this layer, with some data validation and the display of multiple data streams graphically and in context, etc. Other components in this layer include data repositories, GIS or network schematic visualisation tools, control room systems with simple alert rules, graphical control interfaces, water balance applications, and fixed-rule feedback automation.
The data fusion and analysis layer brings together raw input data and derives processed knowledge, which was not previously obvious or trivial from the data as collected. The resulting information may be displayed to a human operator, passed on to further analysis within the layer, or trigger automatic action by means of the data handling layer (or directly via the communications layer). The value of this information comes from sifting through the flood of data from multiple samples, data sources, and even data types, to extract high value information, in the form of alerts on problems, automated responses to system changes, high level summaries, network forecasts, etc.
Components in this layer may include hydraulic modelling systems, network infrastructure monitoring, smart pressure management, smart (not fixed feedback) pumping or energy optimisation systems, and Decision Support Systems. This layer contains many promising emerging technologies, enroute to a true “Smart Water Grid.”