Hydrology Pressures

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

Hydrology Pressures

A previous Put the Pressure on Us blog post (Nileometer), showed how the ancient Egyptians measured the amount of annual flooding of the Nile to predict the future crop harvest. Today, a staff gage with a vertical scale indicates the elevation of water, or stage in wetlands relative to a reference elevation. The water level measurement is one key aspect of wetland hydrology to monitor the transition zone between pre-dominantly wet (lakes, rivers, etc.) and dry environments.

Example of a United States Geological Survey (USGS) style staff gage. Source: EPA

Example of a United States Geological Survey (USGS) style staff gage. Source: EPA.

However, “Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams,” published by the U.S. Environmental Protection Agency, provides information regarding the use of vented (gage) and non-vented (absolute) pressure transducers for Regional Monitoring Networks (RMNs). An accuracy of ≤ 0.015 feet, or 0.18 inches (.0065 psi), is recommended. In its guidance on how to collect accurate, year-round temperature and hydrologic data the report notes that “because atmospheric pressure changes with weather and altitude, compensating for barometric variations is necessary; failure to account for these variations could result in errors of 0.6 m (2 ft) or more.” An All Sensors SPA 401 or SPM 401 piezoresistive silicon pressure sensor with stainless steel interface and media isolation could be used in this type of application.

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