Joe Hostler, environmental scientist, Yurok Tribe installing soil moisture probe

The U.S. Geological Survey (USGS) often employs specific types of soil moisture probes to monitor watersheds, creeks, and streams as part of their hydrological studies and environmental monitoring efforts. For such applications, the probes must be robust, accurate, and capable of providing data critical for understanding hydrological cycles, predicting floods, and managing water resources. Here are some common types of soil moisture probes and technologies that might be used by the USGS in these environments:

1. Time Domain Reflectometry (TDR) Probes: Due to their high accuracy and reliability, TDR probes are frequently used in scientific research and monitoring by organizations like the USGS. These probes can provide precise measurements of soil moisture at various depths, which is essential for calculating the amount of water entering or leaving a watershed.
2. Capacitive Probes: These are useful for continuous monitoring because they can be left in the field for long periods with minimal maintenance. Capacitive probes are less invasive and can be used to monitor changes over time, helping in the analysis of seasonal and weather-related variations in soil moisture.
3. Soil Moisture and Temperature Probes: In watershed monitoring, understanding the relationship between soil moisture and temperature can be crucial. These probes measure both and can help model the effects of temperature changes on moisture dynamics and vice versa.
4. Neutron Moisture Gauges: Although more complex and requiring special handling due to their use of radioactive materials, neutron moisture gauges provide very accurate soil moisture readings. They are particularly useful in research projects where precision is critical for developing water budget models and other analyses.
5. Automated Soil Moisture Stations: For comprehensive watershed monitoring, the USGS might install automated stations that include multiple types of sensors, including soil moisture probes. These stations can provide real-time data remotely, which is essential for timely decision-making and long-term environmental monitoring.

These tools enable the USGS to gather detailed data that contribute to their understanding of hydrological processes, assist in flood forecasting, and support water resource management across different terrains and climatic conditions.