scholarly journals Application of the method of spatial point pattern analysis to the horizontal spatial distribution of preferential flow paths

2015 ◽  
Vol 91 (04) ◽  
pp. 384-394
Author(s):  
Wenxing Lu ◽  
Jinhua Cheng ◽  
Wei Wang ◽  
Hongjiang Zhang ◽  
Hongwen Zhou
Keyword(s):  
Spatial Distribution ◽  
Preferential Flow ◽  
Pattern Analysis ◽  
Point Pattern Analysis ◽  
Plant Roots ◽  
Water Volume ◽  
Point Pattern ◽  
Analysis Method ◽  
Flow Paths ◽  
Preferential Flow Paths

Preferential flow significantly influences hydrological processes in forests. The occurrence and development of this flow is directly affected by its spatial distribution. To determine whether or not point pattern analysis method can be used to examine the horizontal spatial distribution of preferential flow paths, experiments were conducted with dye tracer permeation to observe flow processes. Results indicated that an increase in penetration water volume exerted only a specific effect on preferential flow paths of large class in the topmost soil. Moreover, such paths showed distinct clumped patterns at the 25-cm scale under both high permeation water volume and low permeation water volume treatments. Nonetheless, the distribution pattern became uniform as scale range increased. The significance of the correlation between the spatial distribution of preferential flow paths and plant roots decreased from the top soil layer to the bottom. These findings suggest that soil depth and water permeation volume are important to the horizontal spatial distribution of preferential flow paths. Moreover, point pattern analysis method is suitable for investigating the horizontal spatial distribution of preferential flow paths and determining the correlation between the spatial distribution of preferential flow paths and plant roots.

scholarly journals Analyzing the Spatial Distribution of Drumlins: A Two-Phase Mosaic Approach

1984 ◽  
Vol 30 (106) ◽  
pp. 302-307
Author(s):  
B. N. Boots ◽  
R. K. Burns
Keyword(s):  
Spatial Distribution ◽  
Pattern Analysis ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Statistical Bias ◽  
Two Phase ◽  
Alternative Approach ◽  
Mosaic Approach ◽  
The Individual

AbstractResearchers have analyzed various properties of drumlins within individual drumlin fields in order to provide evidence to help in identifying the processes involved in drumlin formation. One property which has been examined is the spatial distribution of drumlins within a field. Traditionally, in such endeavours the individual drumlins have been represented as points and their distribution examined using techniques of point-pattern analysis. We suggest that not only is such a representation inappropriate at this scale, it also introduces statistical bias which makes the results of such analyses questionable. Consequently, we propose an alternative approach which involves representing individual drumlins as areal phenomena and considering their pattern as a two-phase mosaic. The advantages of such an approach are discussed and it is illustrated by applying it to two different drumlin fields.

scholarly journals Spatial distribution patterns of plague hosts: point pattern analysis of the burrows of great gerbils in Kazakhstan

2015 ◽  
Vol 42 (7) ◽  
pp. 1281-1292 ◽  
Author(s):  
Liesbeth I. Wilschut ◽  
Anne Laudisoit ◽  
Nelika K. Hughes ◽  
Elisabeth A. Addink ◽  
Steven M. de Jong ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Pattern Analysis ◽  
Distribution Patterns ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Spatial Distribution Patterns

scholarly journals Analyzing the Spatial Distribution of Drumlins: A Two-Phase Mosaic Approach

1984 ◽  
Vol 30 (106) ◽  
pp. 302-307 ◽  
Author(s):  
B. N. Boots ◽  
R. K. Burns
Keyword(s):  
Spatial Distribution ◽  
Pattern Analysis ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Statistical Bias ◽  
Two Phase ◽  
Alternative Approach ◽  
Mosaic Approach ◽  
The Individual

AbstractResearchers have analyzed various properties of drumlins within individual drumlin fields in order to provide evidence to help in identifying the processes involved in drumlin formation. One property which has been examined is the spatial distribution of drumlins within a field. Traditionally, in such endeavours the individual drumlins have been represented as points and their distribution examined using techniques of point-pattern analysis. We suggest that not only is such a representation inappropriate at this scale, it also introduces statistical bias which makes the results of such analyses questionable. Consequently, we propose an alternative approach which involves representing individual drumlins as areal phenomena and considering their pattern as a two-phase mosaic. The advantages of such an approach are discussed and it is illustrated by applying it to two different drumlin fields.

Interaction Between Plant Roots and Soil Water Flow in Response to Preferential Flow Paths in Northern China

2016 ◽  
Vol 28 (2) ◽  
pp. 648-663 ◽  
Author(s):  
Yinghu Zhang ◽  
Jianzhi Niu ◽  
Mingxiang Zhang ◽  
Zixing Xiao ◽  
Weili Zhu
Keyword(s):  
Soil Water ◽  
Water Flow ◽  
Preferential Flow ◽  
Northern China ◽  
Plant Roots ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Soil Water Flow

scholarly journals Spatial point pattern analysis of prehospital naloxone administrations

2017 ◽  
Author(s):  
Christopher Ryan
Keyword(s):  
United States ◽  
Monte Carlo Simulation ◽  
Spatial Distribution ◽  
Pattern Analysis ◽  
Spatial Clustering ◽  
The United States ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Opioid Overdose ◽  
Spatial Point

AbstractObjectivesThe increasing problem in the United States with opioid dependence and overdose, often fatal, is well-recognized. As naloxone has only one clinical use—the treatment of opioid overdose—its administration by EMS personnel can serve as a surveillance indicator for opioid overdose. This study uses specific locations of EMS calls, and methods of point pattern analysis, to detect overall spatial clustering among EMS naloxone administrations compared to EMS calls in general.Study DesignA cross-sectional study of incident locations of EMS responses in a three-county EMS region in the United States.MethodsRepeated random samples from the spatial distribution of all EMS calls were used, in a Monte Carlo simulation, to represent the background inhomogeneity of the population. Observed F, G, and inhomogeneous K and L functions from the spatial distribution of naloxone-involved calls were compared to their null sampling distributions obtained from the Monte Carlo simulation.ResultsCases of naloxone administration demonstrated spatial clustering in the range of 0 to 5000 meters, and particularly around 2500 meters, beyond what could be attributable to the spatial heterogeneity of all EMS calls.ConclusionsEfforts to understand the fundamental nature of opioid overdose as a spatial point process could yield innovative public health interventions to control the epidemic.

Visualizing Preferential Flow Paths using Ammonium Carbonate and a pH Indicator

2002 ◽  
Vol 66 (2) ◽  
pp. 347 ◽  
Author(s):  
Zhi Wang ◽  
Jianhang Lu ◽  
Laosheng Wu ◽  
Thomas Harter ◽  
William A. Jury
Keyword(s):  
Preferential Flow ◽  
Ammonium Carbonate ◽  
Ph Indicator ◽  
Flow Paths ◽  
Preferential Flow Paths

Equation for Describing Solute Transport in Field Soils with Preferential Flow Paths

2005 ◽  
Vol 69 (2) ◽  
pp. 291-300 ◽  
Author(s):  
Young-Jin Kim ◽  
Christophe J. G. Darnault ◽  
Nathan O. Bailey ◽  
J.-Yves Parlange ◽  
Tammo S. Steenhuis
Keyword(s):  
Solute Transport ◽  
Preferential Flow ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Field Soils

Dynamic Modeling of Channel Formation During Fluid Injection Into Unconsolidated Formations

SPE Journal ◽  
2015 ◽  
Vol 20 (04) ◽  
pp. 689-700 ◽  
Author(s):  
S.. Ameen ◽  
A. Dahi Taleghani
Keyword(s):  
Preferential Flow ◽  
Volume Fraction ◽  
Injection Pressure ◽  
Internal Erosion ◽  
Fluid Injection ◽  
Critical Threshold ◽  
Model Parameters ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Stress Changes

Summary Injectivity loss is a common problem in unconsolidated-sand formations. Injection of water into a poorly cemented granular medium may lead to internal erosion, and consequently formation of preferential flow paths within the medium because of channelization. Channelization in the porous medium might occur when fluid-induced stresses become locally larger than a critical threshold and small grains are dislodged and carried away; hence, porosity and permeability of the medium will evolve along the induced flow paths. Vice versa, flowback during shut-in might carry particles back to the well and cause sand accumulation inside the well, and subsequently loss of injectivity. In most cases, to maintain the injection rate, operators will increase injection pressure and pumping power. The increased injection pressure results in stress changes and possibly further changes in channel patterns around the wellbore. Experimental laboratory studies have confirmed the presence of the transition from uniform Darcy flow to a fingered-pattern flow. To predict these phenomena, a model is needed to fill this gap by predicting the formation of preferential flow paths and their evolution. A model based on the multiphase-volume-fraction concept is used to decompose porosity into mobile and immobile porosities where phases may change spatially, evolve over time, and lead to development of erosional channels depending on injection rates, viscosity, and rock properties. This model will account for both particle release and suspension deposition. By use of this model, a methodology is proposed to derive model parameters from routine injection tests by inverse analysis. The proposed model presents the characteristic behavior of unconsolidated formation during fluid injection and the possible effect of injection parameters on downhole-permeability evolution.

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