The rapid growth of urban areas throughout the world and advances in technology and industry to meet society’s ever increasing demands for more goods, energy, etc. have greatly increased the potential for environmental pollution. They have also contributed to an increasing awareness of and concern for the environment. Population density and advanced technology continue to place increasing demands on society to control the quality and conserve the supply of water.
Increasingly strict legislation and continuing public interest in conservation and environmental matters have emphasized the importance of flow measurement. Uniform and reliable measurement data are needed to identify the resource levels and quality of bodies of water, to determine the results of conservation and quality control efforts, and to enforce water conservation and quality regulatory requirements.
The majority of recent interest in flow measurement has centered on water quality regulatory requirements. For example, in the United States, federal law states that “…the purpose of self-monitoring and reporting effluent data is to permit federal and state regulating agencies to follow on a continuing basis, the discharger’s effluent quality trends as well as specific variation from established limitations.”
Local agencies in the U.S. are required by the same legislation to establish a local surcharge on industrial waste to insure that these users pay their “fair share” of the cost of existing and new treatment facilities. Their “fair share” entails the measurement of both the quality and the quantity of industrial discharge. Thus, an economic value has been placed on industrial waste, and it is important for both industrial dischargers and municipalities to be able to measure and record flow data.
There are variations of environmental monitoring regulations throughout the world. There are often layers from national to regional, and a number of local levels for regulatory law as well as enforcement agencies. The purpose of this handbook, however, is not to define the protocols of environmental flow monitoring, but to address the field in general. You should always consult your local regulatory agency regarding the standard practices and requirements for your specific monitoring location.
Of course, flow measurement still is of great importance in more traditional areas such as irrigation, stream measurement, and sewage treatment plants. It also has other applications, for example, in storm and combined sewer flow studies, in sedimentation work, in runoff studies, and inflow and infiltration isolation. As Kirkpatrick and Shelley state: “Measurements of quantity of flow, usually in conjunction with sampling for flow quality, are essential to nearly all aspects of water pollution control. Research, planning, design, operation and maintenance, and enforcement of pertinent laws—all are activities which rely on flow measurement for their effective conduct.”
Thus in the context of modern society, there is an ever increasing need for simple, accurate, and reliable methods of flow measurement. These needs are usually dictated by legislation, but in a larger sense are dictated by society’s desire to reverse the trend of increasing environmental pollution, and to ensure a clean, livable planet for this and future generations.
Frequently Asked Questions
What is the unit of measurement for the flow of water?
Flowing water is measured in units of volume per unit of time – gallons per minute (gpm), cubic feet per second (cfs), acre-inches per hour, or acre-feet per day.
How do you quantify the flow of water?
To calculate the water flow (in m3) multiply the average water velocity (in m/s) by the average width (in m) and by the average depth (in m).
How do you measure the flow rate of water in a pipe?
A simple formula is: Q = V/t, where: Q = Flow rate (typically measured in liters per minute or gallons per minute). V = Volume of fluid (in liters or gallons). T = Time (in seconds).
