PI: Colin Everson (University of KwaZulu-Natal)
U.S. Partner: Marek Zreda (University of Arizona)
Project Dates: August 2013 to September 2015
Dr. Colin Everson (right) and a student with the cosmic ray probe at the Baynesfield Estate in KwaZulu-Natal (Photo courtesy Dr. Everson).
This PEER Science project leverages the recent development of the Cosmic Ray Probe (CRP) as part of a National Science Foundation-supported project. The CRP uses cosmic-ray neutrons to measure soil moisture content over an area of tens of hectares. Dr. Colin Everson and his research team will test the suitability of a cosmic ray moisture probe in providing data for the continued support of soil moisture modeling of South Africa using a hydrologically consistent land surface model, accurate field and satellite-scale estimates of soil moisture for the calibration of hydrometeorogical models, and estimation of the spatial variability of soil moisture at catchment scale.
The researchers plan to build capacity in South Africa by developing a network to extend the cosmic ray moisture probes to multiple applications. Measurements using the probe at area scales of up to 34 hectares have the potential to provide hydrometeorologists with an entirely new way of evaluating surface soil water at spatial scales never achieved with ground-based techniques. This will provide water resource managers, engineers, and agriculturalists with an invaluable but economical new tool to monitor the critical interface between the ground and atmosphere. This new technology can be employed in water demand forecasting and promises to improve the utilization of irrigation water, especially in water scarce regions like South Africa. The probe can also be used for predictive weather and climate models by measuring soil water content. This is currently a major source of uncertainty in weather and climate forecasts, due largely to a lack of suitable observations. The project should also improve the quality of soil moisture data that feed into the South African Flash Flood Guidance System, which provides alerts to the public based on current and predicted rainfall. The system currently uses a relatively crude evaporation model. Therefore, the application of CRP data should help in validating evaporation estimates with better temporal and spatial resolution, thus improving the accuracy of flash flood predictions.
Summary of Recent Activities
During the last quarter of 2014, the team analyzed samples of the daily national Soil Moisture and Evapotranspiration estimates on a grid of 7300 locations and compared the results using the HYLARSMET system. The system estimates were compared with detailed evapotranspiration and soil moisture measurements made at the Baynesfield experimental farm in the KwaZulu-Natal province of South Africa. Overall, the evapotranspiration estimates compared very well with the measured estimates for the two chosen crop types. The same seasonality effects were evident in all three estimates, but the system estimates proved to be most accurate at the soybean site. Overall the team found a reasonably strong relationship between HYLARSMET and the in situ measurements at each site and will present the results at the European Geospatial Union.
In the new year, Professor Trenton Franz, one of the PEER partners, will visit South Africa from 20 January to 31 January to help with project data estimates and calibration. He will help mentor two new MSc students who will work on the cosmic ray probe technology and soil water measurement across a range of sites. Additionally, a new Cosmic Ray Probe will be installed at Mapungubwe National Park to assess the impact of pumping water from the Venetia mine and well fields near a rare gallery forest. The team will also continue to gather field measurements of ET and soil water and will measure them against established models. Additional data will be obtained from Landsat satellite images and used to identify and study the project focus areas in greater detail and depth.
Article from website of the University of KwaZulu-Natal (December 2013)
Article from South African Environmental Observation Network newsletter (December 2013)
Article from Farmer's Weekly (January 10, 2014)