Abstract

CRUZ BAUTISTA, Fidencio et al. In situ calibration of cosmos sensor to determine the soil moisture at an intermediate scale (~1 km). Terra Latinoam [online]. 2013, vol.31, n.4, pp.315-324. ISSN 2395-8030.

Soil heterogeneity greatly influences moisture content, making it difficult to accurately determine this parameter in hydrological and ecological studies that require continuous representative measurements at intermediate scales (~1 km). In this context, the COsmic-ray Soil Moisture Observing System (COSMOS) enables us to quantify soil moisture continuously at spatial scales of hundreds of meters. The objective of this study was to evaluate a scheme for calibrating a COSMOS CRS-1000 sensor. The study was conducted in a buffel grass (Pennisetum ciliare) savanna in Rayon, Sonora, Mexico. Here, a COSMOS CRS-1000 was installed, and for calibration, two soil samplings were conducted. These samples were analyzed for moisture content and bulk density by gravimetric techniques. The moisture content of the samples, expressed in terms of volume, was used to obtain the calibration parameter by approximation for the CRS-1000 COSMOS. The value for this parameter was 4121counts per hour (neutron count rate of soil). With this value, correction to the values originally estimated by COSMOS CRS-1000 sensor was performed. With this correction, there was an increase in soil moisture content of 1 to 2% compared with the values estimated with the CRS1000 COSMOS throughout the period of analysis. Despite the spatial variability in the moisture content of the soil under study, it was observed that the CRS-1000 COSMOS sensor has the capability of providing a reasonable continuous estimate of moisture content soil to a depth of 0 to 40 cm, in an area of about 30 ha.

Keywords : precipitation; cosmic rays; neutrons; Rayon Sonora; buffel grass.

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