Distant Monitoring: Live Water Level Readings
For decades, a small river near a writer's childhood home had a seemingly insignificant role in their life—a playground during their youth and an occasional subject of curiosity due to a mysterious instrument standing beside it. Emitting the logo of the United States Geological Survey (USGS), the contraption was recognized as a streamgage, part of a vast network designed to monitor the nation's waterways.
Now, the writer has come to appreciate the device's true significance. This week, they learned about the workings of streamgages, the extent and maintenance efforts behind the USGS's network, and its impact on everyday life.
While some may consider 'gage' an uncommon spelling of 'gauge,' it is, in fact, the preferred terminology by the USGS. This is highlighted by the agency's FAQ regarding this topic, a testament to the frequency of the question.
The first streamgaging station was established in 1889 along the Rio Grande River at a railroad station in Embudo, New Mexico. Manual measurements were performed by teams trained in hydrography, and many of the techniques used to measure the flow of rivers across the West throughout the 19th century and later were perfected at Embudo.
The critical measurement in river monitoring is the discharge rate, the volume of water passing a point in a fixed period. Measured in cubic feet per second in the U.S., discharge rate ranges from minor streams to the colossal Mississippi River's over one million cubic feet per second during springtime.
The USGS calculates discharge rates indirectly using stream height, often called flood stage. While direct measurement is more complex, indirect calculation allows for easier, continuous measurements with various techniques based on each site's specific requirements.
A common technique is the stilling well, a vertical shaft dug into the bank adjacent to a river. The shaft is lined with impervious materials, and the bottom lies below the riverbed, while the height corresponds to the highest expected flood stage. The well is connected to the river via input pipes, and the level inside the well mirrors the level of the water in the river, providing a stable column for measurement.
An alternative method is the bubble gage, which measures river stage using gas pressure. A positive pressure through the orifice tends to keep silt out of the works, making it an effective choice for rivers with high silt loads. However, bubble gages require a steady supply of electricity or bottled gas for continuous operation, as well as minimizing the pipe run to the orifice for easier maintenance.
Despite minor challenges, streamgages play a crucial role in water management by providing essential data on daily streamflow conditions, flood forecasting, and real-time data access during emergencies. This information helps water resource managers and emergency responders make informed decisions and prepare for weather-related events. With continual advancements in monitoring technology and data analysis, the USGS streamgaging network—rooted in history but adapting to modern concerns—continues to provide invaluable insights into our nation's water resources.
Science and environmental science now hold a significant role in the writer's understanding of the streamgage, a tool traditionally associated with the USGS for data collection on climate-change effects and the environment. Today, technology and data-and-cloud computing are essential components in maintaining the network and interpreting the vast data streamgages produce, providing critical information for water management, climate-change research, and emergency response.
