On the fifth anniversary of the launch of the first COSMOS-UK site, Hollie Cooper, a Research Associate at the Centre for Ecology & Hydrology, looks at the origins and growth of our pioneering soil moisture monitoring network.
October 2, 2018, marked five years since the installation of the first COSMOS-UK soil moisture site, located at Chimney Meadows in West Oxfordshire.
Chimney Meadows was installed by the Centre for Ecology & Hydrology as the first in a network of environmental monitoring stations that utilise innovative technology to measure large-scale soil moisture.
Traditional soil moisture sensors measure soil moisture in a volume of soil similar in size to a football, whereas the cosmic-ray sensors at COSMOS-UK sites have a sample size, or footprint, approximately equivalent to 12 football pitches.
This new monitoring technology is based on counting neutrons that originate in cosmic-rays, hence the name of the network: ‘Cosmic-ray Soil Moisture observing Network for the UK’ or COSMOS-UK.
The neutron count detected by the sensor is corrected for local meteorological conditions and the background cosmic-ray flux arriving in the Earth’s upper atmosphere, to provide the average volumetric water content in the sensor footprint.
Why is measuring soil moisture important?
This summer has been particularly interesting and unusual as there has been a prolonged spell of very low soil moisture, affecting crop yields. The hot, dry conditions also exacerbated the spread of wildfires in some areas of the UK.
Monitoring the water content of the soil can enable highly-efficient irrigation, providing water when required and eliminating wasteful use. Observing soil moisture variability also increases our knowledge of how the natural environment functions and how it responds to change. The availability of these data can enable improved understanding of the relationship between soil moisture, evaporation, evapotranspiration and local weather systems.
Soil acts as part of a water storage system that regulates the passage of water from rainfall arriving at the land surface to its return to the sea, meaning some rivers continue to flow long after rain has stopped, perhaps for months or even years. Improved knowledge of large-area soil moisture can therefore support flood forecasting and drought monitoring.
Measuring soil moisture and understanding its variability with location and through time is fundamental when exploring potential effects of climate change. This data also helps to project future water availability for agriculture, industry, domestic consumption and the environment.
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