Soil Moisture Measurements in Morocco
- PMARS project group near the GNSS-R station for soil moisture determination.
- © GFZ
the climate change, there is an increase in the frequency of extreme
weather situations (like droughts or flooding events). For that
reason, observations of water level and soil moisture are required in
order to be able to improve the hydrological models, especially in
areas with agricultural background like Morocco.
Satellite based altimetry (JASON-2) or soil moisture measurements (SMOS) provide high accuracy data but show a low spacio-temporal resolution. Ground based measurements also have a high accuracy and a good temporal resolution but are restricted to one location only. GNSS-Reflectometry (GNSS-R) combines both methods and provides a compromise in the spacio-temporal resolution.
The goal of the Morocco-German research project PMARS (Programme Maroc-Allemand de Recherche Scientifique) is to build up a basis for scientific collaborations and the improvement of hydrological modelling with soil moisture and water level measurements. The scientific collaboration is between the GFZ and the Analysis laboratory for hydraulic systems from the University of Mohammedia for engineers in Rabat, Morocco. The project is funded by the German and Moroccan Ministry of Education and Research.
A measuring campaign was conducted starting 12/16/2013 close to the Hassan II dam in Midelt, Morocco (32°47´30.06´´N, 4°46´06.21´´W)
Within that campaign, two GNSS-R measurements were started. One measuring station was placed directly at the railing of the dam with the goal of measuring water level changes. To track the direct and reflected GPS signals separately, three antennas were used. The first antenna, for the direct signals was facing zenith direction, whereas the other two antennas were directed towards the water for the tracking of the reflected GPS signals (L1 and L2).
The second station has the goal of measuring the soil moisture using GNSS-R. This station will keep measuring for one year, the gain statistically reasonable dataset. To extract soil moisture data, a calibration of the GNSS-R data must be applied. Therefore, soil moisture sensors were embedded in the ground close-by. Additionally, soil samples are extracted and analyzed, with the respect to soil moisture.
 K. M. Larson, J. J. Braun, E. E Small, V. U. Zavorotny, E. D. Gutmann, and A. L. Bilich: : GPS Multipath and Its Relation to Near-Surface Soil Moisture Content, IEEE JSTARS, Vol. 3, No. 1, 2010, Doi: 10.1109/JSTARS.2009.2033612.
 J. Beckheinrich, G. Beyerle, S. Schön, H. Apel, M. Semmling, J. Wickert: WISDOM: GNSS-R based flood monitoring, in Proc. IEEE Workshop on Reflectometry Using GNSS and Other Signals of Opportunity (GNSS+R), 10–11, 2012. Doi: 10.1109/GNSSR.2012.6408257
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