The Scale Effect of Double-Ring Infiltration and Soil Infiltration Zoning in a Semi-Arid Steppe

Abstract

The double-ring infiltrometer is widely used to measure soil unsaturated hydraulic conductivity in the field. The scale effect of the inner and outer ring size (especially the inner one) affects the measurement results. In the semi-arid steppe, where water is scarce and transportation is inadequate, studying the scale effect caused by the inner-ring diameter of the infiltrometer can reduce the test consumption on the premise of ensuring the test accuracy. In this paper, a total of 190 double-ring infiltration tests with different inner-ring diameters (15,20,25,30, and 40 cm) and 0.33 times outer buffer index were carried out at 38 sites with five soil types in the Xilin river basin, China. Results showed that: (1) When comparing the simulated parameters of six infiltration models, parameters increased with the increase of the infiltrometer inner diameter, but the trend gradually slowed down, indicating that the increase of the infiltrometer inner diameter would weaken the influence of the infiltrometer scale effect. However, the infiltrometer with an inner diameter of 40 cm is not enough to completely overcome the scale effect. (2) Through principal component analysis, the infiltration process is mainly affected by the particle size and the initial moisture content. (3) The soil infiltration map based on infiltration tests was more practical than the soil type map, which can provide a theoretical basis for ecological and soil restoration in the future. species diversity does not reduce, but rather improves, the soil erosion resistance [13,14], and finally allows the whole ecosystem to achieve a positive cycle [15].To achieve the goal of obtaining the soil water retention characteristics of the study area, it is necessary to accurately evaluate this capacity, which can be estimated by the final infiltration rate (FIR) and infiltration time when the infiltration rate first reaches the final infiltration time (FIT). A slower infiltration rate indicates that the soil has better water retention [10]. The process of soil infiltration can be simulated in the laboratory using the ring-knife or a soil column [16,17]. However, such studies are influenced by disturbances of the original soil bulk density, porosity, and other soil physical properties. Instead, an infiltration test based on in situ undisturbed soil is capable of reflecting the original state of soil more effectively.Compared with a single-ring infiltrometer, a double-ring infiltrometer can be used to construct an infiltration buffer, which reduces the main external interference factors on the infiltration process of the inner ring [18]. Previous studies have shown that the average infiltration rate increases with the infiltrometer diameter [19,20]. Lai et al. [21] found through a large number of simulations that, compared with the outer buffering index (bi), the inner-ring diameter (di) plays a more important role in obtaining a relatively stable and representative measurement result. When the bi is equal or larger than 0.33, the buffer may meet the measureme...

The study of soil infiltration in west part of Semarang City, Indonesia

“…Low correlation results were also produced in research by Fitzgerald et al [21] and concluded that there might have been other parameters with better correlation, either the infiltration measurement method using the infiltrometer was not reliable, caused by plugging the infiltrometer into the soil, which disturbed the physical properties of the soil, therefore the soil inside the ring did not represent the type of soil around it. Another factor is due to the effect of size scale of the used ring infiltrometer, in which according to Li et al [22], the double-ring infiltrometer is having a size-scale impact where the larger the ring size in the used infiltrometer, the scale effect decreases, and the scale effect does not occur when using a 40-cm diameter inner ring.…”

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“…The double-ring infiltration experiments were conducted in four samples a, b, c, and d during the regreening and wilting stages in 2021 ( Rnnqvist, 2018 ), and we obtained data on the saturated hydraulic conductivity of the soil at each experimental site in the study area during the regreening and wilting stages ( Table 2 ). The experimental equipment was the DJ-IN12-W double-ring infiltrator, whose inner and outer ring diameters were 60 and 30 cm, respectively, to minimize the influence of soil spatial heterogeneity on the experiment ( Li et al., 2019 ). The Mariotte tubes with volumes of 3 and 10 l were configured to supply water to the inner and outer rings, respectively.…”

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