Soil Mass, Surface, and Spectral Fractal Dimensions Estimated from Thin Section Photographs

Anderson, Alison N.; McBratney, Alex B.; Fitzpatrick, E. A.

doi:10.2136/sssaj1996.03615995006000040002x

Cited by 121 publications

(79 citation statements)

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“…A large number of studies have been reported to apply fractal theory applied in describing porous media structure and microscopic morphology characteristics, such as soil and sediment. Therefore, the fractal theory was used to analyze the morphology of biofilms as a porous media (Anderson et al 1996;Wang and Lu 2005). The study found that the biofilms attached on these two types of surfaces had obvious multifractal characteristics.…”

Section: Discussionmentioning

confidence: 99%

Structural and fractal characteristics of biofilm attached on the surfaces of aquatic plants and gravels in the rivers and lakes reusing reclaimed wastewater

Liang

Wang

et al. 2013

Environ Earth Sci

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Reusing reclaimed wastewater from lakes has become one of the most effective measures to relieve the urban ecological crisis. However, reclaimed wastewater still contains large amounts of nutrient salts, trace organic pollutants, suspended solid particles and microorganisms, which may significantly affect the aquatic ecosystems. The health of aquatic ecosystems can be directly and effectively monitored by evaluating the biofilms in them, because the structures of biofilms are directly affected by multiple environmental factors. Therefore, it is important to study the structures of biofilms attached on multiple medium surfaces in river-lake systems that contain reclaimed wastewater. In this study, the paper applied scanning electron microscope (SEM) technology and fractal theory to quantitatively describe the structural characteristics of biofilms attached on the medium surfaces of aquatic plants and gravels in the Lianshi Lake of Beijing Yongding River and other two kinds of reclaimed water of the river-lakes, whose sewage treatment processes were the combined process of deposit and sand filtration and UF membrane filtration, plus anaerobic-anoxic-oxic process, respectively. The paper found that these two types of biofilms were typical porous media and their basic skeletons were mainly composed of inorganic particles, microorganisms, and algae. Furthermore, most areas between the particles were filled with extracellular polymers (EPS) secreted by bacteria. At the same time, these biofilms showed obvious fractal and multifractal characteristics, but the fractal dimensions alone failed to effectively describe the complexity of biofilm structures. The multifractal spectra were able to quantitatively characterize the biofilms' heterogeneity. In addition, the number of microorganism species, the quantity and the heterogeneity of aquatic plants' surface biofilms were all higher than those of gravel surface biofilms, most likely due to the effects of light. In addition, the heterogeneity of biofilms in reclaimed water treated by the combined process of deposit and sand filtration and UF membrane filtration plus anaerobic-anoxic-oxic process was higher than that of biofilms in reclaimed water treated by traditionally activated sludge process (Lianshi Lake's water). Besides, the non-uniformity of biofilms in reclaimed water treated by combined process of deposit and sand filtration was higher than that of biofilms in reclaimed water treated by UF membrane filtration plus anaerobic-anoxic-oxic process.

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Section: Discussionmentioning

confidence: 99%

Structural and fractal characteristics of biofilm attached on the surfaces of aquatic plants and gravels in the rivers and lakes reusing reclaimed wastewater

Liang

Wang

et al. 2013

Environ Earth Sci

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“…For the soil-related parameters include the water content at saturation condition, the water content at field condition, the water content at wilting condition, hydraulic conductivity at saturation condition, soil thickness and soil porosity characteristics coefficient b. Based on past modeling experiences and references (Zeidler, 1993;Anderson et al, 1996), a value of 2.5 is set to b for all soil types, and the water content at wilting condition is set to be 30 % of the water content at the saturation condition. The soil thickness is estimated based on local experiences and listed in Table 3 for all soil types.…”

Section: Parameter Optimizationmentioning

confidence: 99%

Large-watershed flood forecasting with high-resolution distributed hydrological model

Chen

Wang

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. A distributed hydrological model has been successfully used in small-watershed flood forecasting, but there are still challenges for the application in a large watershed, one of them being the model's spatial resolution effect. To cope with this challenge, two efforts could be made; one is to improve the model's computation efficiency in a large watershed, the other is implementing the model on a highperformance supercomputer. This study sets up a physically based distributed hydrological model for flood forecasting of the Liujiang River basin in south China. Terrain data digital elevation model (DEM), soil and land use are downloaded from the website freely, and the model structure with a high resolution of 200 m × 200 m grid cell is set up. The initial model parameters are derived from the terrain property data, and then optimized by using the Particle Swarm Optimization (PSO) algorithm; the model is used to simulate 29 observed flood events. It has been found that by dividing the river channels into virtual channel sections and assuming the cross section shapes as trapezoid, the Liuxihe model largely increases computation efficiency while keeping good model performance, thus making it applicable in larger watersheds. This study also finds that parameter uncertainty exists for physically deriving model parameters, and parameter optimization could reduce this uncertainty, and is highly recom-

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“…The lattice size was always set at 1000 by 1000 cells in order to compare our results with those from the soil thin section images of Anderson et al [1996] which were 1000 by 1000 pixels.…”

Section: Simulated Porous Mediamentioning

confidence: 99%

“…Anderson et al [1996Anderson et al [ , 2000 performed numerical random walk simulations in digitized images of thin sections from a wide variety of soil types. Their results indicate that d w for the pore phase ranges from 2.2 to 2.7.…”

Section: Introductionmentioning

confidence: 99%

“…Three classes of prefractals were investigated: pore, mass, and pore-solid Sierpinski carpets. The main objectives were to investigate the effects of varying porosity and lacunarity on the extent of anomalous diffusion in each simulated porous medium, and to relate the results to those obtained by Anderson et al [1996] for soil thin sections. The goal was to identify the best geometrical model for simulating solute diffusion in saturated soil and reservoir rocks.…”

Section: Introductionmentioning

confidence: 99%

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Anomalous diffusion in two‐dimensional Euclidean and prefractal geometrical models of heterogeneous porous media

Kim

Perfect

Choi

2007

Water Resources Research

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Disordered systems are known to induce anomalous diffusion. This phenomenon may be important for environmental applications such as contaminant transport and nutrient availability. However, few studies have investigated anomalous diffusion in this context. In particular, the relationship between pore space geometry and anomalous diffusion is not well understood. We report on numerical simulations of solute diffusion within the water‐filled pore spaces of two‐dimensional geometrical models of heterogeneous porous media. Euclidean and mass, pore, and pore‐solid prefractal lattices were used to generate random pore networks with varying porosity (ϕ) and lacunarity (L). The objectives were to investigate the effects of ϕ and L on the solute random walk dimension (dw) and to identify which of these models best represents a natural porous medium. Solute diffusion was simulated using a stochastic cellular automaton based on the “myopic ant” algorithm. Estimates of dw ≫ 2 occurred with increasing frequency as ϕ → 0, indicating scale dependency in the standard diffusion coefficient at low porosities. The relationship between dw and ϕ for the mass and pore‐solid prefractal lattices was the closest to that for natural 2‐D systems (i.e., soil thin sections). The presence of large, interconnected pore spaces (L → 1) at low porosities reduced the intensity of anomalous diffusion (dw → 2). A power law relationship based on the product of dw and L explained >96% of the total variation in ϕ regardless of the type of lattice considered. The potential predictive capability of this approach for natural porous media deserves further investigation.

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Soil Mass, Surface, and Spectral Fractal Dimensions Estimated from Thin Section Photographs

Cited by 121 publications

References 0 publications

Structural and fractal characteristics of biofilm attached on the surfaces of aquatic plants and gravels in the rivers and lakes reusing reclaimed wastewater

Structural and fractal characteristics of biofilm attached on the surfaces of aquatic plants and gravels in the rivers and lakes reusing reclaimed wastewater

Large-watershed flood forecasting with high-resolution distributed hydrological model

Anomalous diffusion in two‐dimensional Euclidean and prefractal geometrical models of heterogeneous porous media

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