Effect of hysteresis and rainfall intensity on finger dynamics

Abstract

The purpose of this paper is to present sand-box experiments and a hysteresis model to explain the formation and hydraulic properties of fingered flow. Previous researches have found that a fingered path persists over long periods of constant infiltration; hysteresis could be an important factor. In this paper, a major point is to utilize the boundary and series internal scanning curves of the hysteresis model derived by Huang et al. (2005) to clearly obtain the variations between soil water content (u) and matric suction head (c). The hydraulic properties of fingered flow are also acquired. For the application of the model in the field, the hysteresis curves derived by Hogarth et al. (1988) are compared. Experimental results verified that both hysteresis models and the present soil water content concept model of fingered flow can be adequately applied in field tests. We attempted to use digital image analysis to visualize and determine soil water content of fingered flow easily and quickly. The initial velocity and width of fingered flow were not constant under consistent rainfall intensity. The present concept model showed the matric suction head is uniform between different soil water content sharply in the horizontal direction. Nonuniform soil water content existed even when the potential was horizontally equalized. Copyright # 2008 John Wiley & Sons, Ltd. hauteur d'aspiration est uniforme selon différentes himidité sol en particulier en direction horizontale. Une humidité non uniforme existe même quand le potentiel est lissé horizontalement.

Subsurface flow paths in a chronosequence of calcareous soils: impact of soil age and rainfall intensities on preferential flow occurrence

“…Studies focusing on the formation of finger-shaped flow paths found the finger width to be influenced not only by soil properties and initial and bound-ary conditions (Glass et al, 1989) but also by the flow rate through the finger (Parlange and Hill, 1976;White et al, 1976), with higher flow rates leading to an increase in finger width. This was also observed by Ma et al (2008), who also found a positive correlation between rainfall intensity, time of finger flow occurrence, and mean velocity. The increase in mean velocity of the fingers leads to a faster downward transport and thus deeper infiltration depths with higher irrigation intensities (Cremer et al, 2017).…”

Comments on ‘General scaling rules of the hysteretic water retention function based on Mualem's domain theory’ by Y. Mualem & A. Beriozkin

“…As stated by Viaene et al (1994)‘In those cases, the model presented by Parlange (1976) seems to be the best choice’. This conclusion seems to hold in more recent studies (Si & Kachanoski, 2000; Ma et al , 2008). Mualem & Beriozkin (2009) agree with the conclusion of Viaene et al (1994) when using the main drying curve for a one‐branch model.…”

Characterizing the hydraulic properties of unsaturated sand considering various porosities and drying‐wetting paths of the retention curve

“…The model can describe the main curves and internal scanning curves of WRC regarding both of the wetting and drying processes. It also is applicable for explaining the finger flow phenomenon in sand box experiments (Ma et al ., ), as well as modelling the soil moisture variation (Tan et al ., ).…”