Exploring a Stream’s Flow Rate
A method of flow rate measurement in a shallow stream.Copyright 2021 Rachelle Rasco, Virginia Tech RET
The flow rate of a stream is the amount of water that passes a given point at any given time. The flow rate is a phenomenon that changes due to factors including, but not limited to, heavy rainfall, drought, or the collapse of watershed infrastructure, such as a dam. Therefore, the flow rate is a value that is measured on a continual basis. This monitoring is important for predicting flood conditions, monitoring water quality, managing and allocating water, and for recreational and safety purposes. In this activity, students explore their local stream by using a simple method to measure and calculate the flow rate of that stream. They compare their flow rate calculations measured to the peak flow rate and low flow rates found on the USGS StreamStats site for that location. Students then analyze their methods for measuring flow rate, discuss events that cause flow rates to change, and look at implications of increasing flow rates due to more frequent flood events.
Civil engineers work with the planning, design, construction, and maintenance of structures that serve society, such as roads, highways, bridges, canals, dams, airports, sewage systems, power plants, pipelines, structural components of buildings, and railways. For many of these structures, civil engineers need to understand the local watershed, this includes understanding the flow rates of creeks, streams, and rivers within the watershed. The flow of water in a waterway (for example, in a stream) is directly related to the amount of water moving from the watershed into the stream. The flow rate is affected by weather and can change after major weather events, seasonally and due to human made changes. Knowing a stream’s peak and low flow rates are necessary to predict flooding, monitor impacts of pollutants and sediment, and to know the quantity of water available in a stream.
A special subfield of civil engineering is river engineering which studies human intervention in a river’s path, characteristics or flow to gain some benefit for humans. These benefits may be to protect an area from floods, to increase an area’s irrigation, to manage an area’s water resources, or to make movement along or across rivers easier. In addition, rivers have been engineered to be used as a source of hydropower.
After this activity, students should be able to:
- Calculate the flow rate of a stream.
- Understand that weather and seasonal factors can cause the flow rate to increase or decrease.
- Reflect on how infrastructure and public policies and decisions need to be based on stream flow rates.