FIELD MEASUREMENTS OF WIND EROSION TO BIG SPRING NUMBER EIGHT (BSNE) AND MODIFIED WILSON AND COOK (MWAC) SAMPLERS CALIBRATION

MARIANO J. MENDEZ, ROGER FUNK, DANIEL E. BUSCHIAZZO

Santa Rosa, La Pampa

Congreso; ICARVII (International Conference on Aeolian Research); 2010

International Society for Aeolian Research - ISAR

The Big Spring Number Eight (BSNE, Fryrear, 1986) and the Modified Wilson and Cook (MWAC, Wilson and Cook, 1980, Kuntze et al., 1990) are two of the most common samplers used for measurements of wind erosion. Aim of this study was to compare BSNE and MWAC performances under field conditions. With this purpose wind erosion was measured on a loam sandy soil in 10 erosion events in a 1ha square bare- and flat plot, between December 4, 2008 and July 1, 2009. BSNE samplers collected between 0.002 and 28.4 g of sediment and the MWACs between 0.0009 and 2.97 g. Differences were related to the smaller opening of MWAC samplers, which is 5.6 times smaller than of BSNEs. The horizontal mass flux (HMF) of BSNEs varied between 2.3 10-4 and 2,6 g cm-2, while that of HMF of MWACs varied between 5.3 10-5 and 1.6 g cm-2, being the material collected by MWACs 38% lower than that of the BSNEs. These results agree with samplers efficiency, which varies between 85 and 95% in BSNEs and between 44 and 78% in MWACs. In spite of differences in samplers efficiency, the correlation between HMF obtained with both samplers was significant (P<0.01) either when considering all samples together or when each height was considered separately. The material collected at highest heights was relatively higher for MWACs than for BSNEs. That was explained on the basis of the higher stagnation pressure within BSNEs due to higher wind speeds occurring at higher heights. This effect decreased to a higher extent the BSNE’s sampling efficiency of small particles, which are transported at higher heights. The same equations fitted well HMF as a function of height for both sampler types. Nevertheless, all tested equations fitted better for BSNEs. The horizontal mass transport data (HMT) were comparable among both samplers. Though HMF and HMT obtained with both sampling devices were comparable, BSNE resulted more reliable because their higher efficiency and better adjustment of all tested equations.