Malleable disc base for direct infiltration measurements using the tension infiltrometry technique

✍ Scribed by David Moret-Fernández; Nuria Blanco; Victor Martínez-Chueca; Ana Bielsa

• Publisher: John Wiley and Sons
• Year: 2012
• Tongue: English
• Weight: 497 KB
• Volume: 27
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.9206

✦ Synopsis

The correct use of the tension disc infiltrometer requires the membrane of the disc base to be completely in contact with the soil surface. To achieve this contact, a thick layer of sand is commonly placed between the soil surface and the disc base. This paper presents an alternative disc (M DB ), which, by incorporating a malleable membrane, allows direct infiltration measurements without using a contact sand layer. Infiltration curves obtained with this new design in a soil under three different tillage management treatments were compared with the corresponding curves obtained with a conventional disc (C DB ) that uses a contact sand layer. The cumulative infiltration curves measured with C DB were analysed by the differentiated linearization (DL) method, and the corresponding curves obtained with M DB were analysed using both the DL and the cumulative linearization (CL) models. The values of hydraulic conductivity (K 0 ) and sorptivity (S 0 ) estimated with C DB were also compared with those obtained with M DB . Finally, the cumulative infiltration curves measured with C DB and M DB were compared with the corresponding modelled function for the respective K 0 and S 0 values calculated with the CL and DL models. The results show that, compared with C DB without a contact sand layer, M DB allows complete soil surface wetting even when non-smoothed soil surfaces are used. The C DB , which yielded average K 0 values 18% lower than those estimated with M DB , gave the highest values of standard error for the hydraulic parameters calculated. Furthermore, the subjective method employed in the C DB -DL technique, which requires the first points of the differential infiltration line corresponding to the sand layer to be manually removed, introduces additional uncertainties in estimating S 0 and K 0 . Comparison between the modelled and measured infiltration curves demonstrates that the DL or CL methods applied to M DB gave excellent estimates of S 0 and K 0 .