scholarly journals Flood generation: process patterns from the raindrop to the ocean

2022 ◽  
Author(s):  
Günter Blöschl
Keyword(s):  
Preferential Flow ◽  
Spatial Scales ◽  
Small Scale ◽  
Generation Process ◽  
Pore Scale ◽  
Essential Characteristic ◽  
Flow Paths ◽  
River Flood ◽  
Scale Range ◽  
Flood Generation

Abstract. This article reviews river flood generation processes and flow paths across space scales. The scale steps include the pore, profile, hillslope, catchment, regional and continental scales, representing a scale range of a total of 10 orders of magnitude. Although the processes differ between the scales, there are notable similarities. At all scales, there are media patterns that control the flow of water, and are themselves influenced by the flow of water. The processes are therefore not spatially random (as in thermodynamics) but organised, and preferential flow is the rule rather than the exception. Hydrological connectivity, i.e. the presence of coherent flow paths, is an essential characteristic at all scales. There are similar controls on water flow and thus on flood generation at all scales, however, with different relative magnitudes. Processes at lower scales affect flood generation at the larger scales not simply as a multiple repetition of pore scale processes, but through interactions, which cause emergent behaviour of process patterns. For this reason, when modelling these processes, the scale transitions need to be simplified in a way that reflects the relevant structures (e.g. connectivity) and boundary conditions (e.g. groundwater table) at each scale. In conclusion, it is argued that upscaling as the mere multiple application of small scale process descriptions will not capture the larger scale patterns of flood generation. Instead, there is a need to learn from observed patterns of flood generation processes at all spatial scales.

scholarly journals Field investigation of preferential fissure flow paths with hydrochemical analysis of small-scale sprinkling experiments

2014 ◽  
Vol 2 (1) ◽  
pp. 181-195 ◽  
Author(s):  
D. M. Krzeminska ◽  
T. A. Bogaard ◽  
T.-H. Debieche ◽  
F. Cervi ◽  
V. Marc ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Unsaturated Zone ◽  
Preferential Flow ◽  
Field Investigation ◽  
Hydrological Processes ◽  
Small Scale ◽  
Flow Paths ◽  
Hydrochemical Analysis ◽  
Preferential Flow Paths ◽  
Spatial Differences

Abstract. The unsaturated zone largely controls groundwater recharge by buffering precipitation while at the same time providing preferential flow paths for infiltration. The importance of preferential flow on landslide hydrology is recognised in the literature; however, its monitoring and quantification remain difficult. This paper presents a combined hydrological and hydrochemical analysis of small-scale sprinkling experiments. It aims at showing the potential of such experiments for studying the spatial differences in dominant hydrological processes within a landslide. This methodology was tested in the highly heterogeneous black marls of the Super-Sauze landslide. The tests were performed in three areas characterised by different displacement rates, surface morphology and local hydrological conditions. Special attention was paid to testing the potential of small-scale sprinkling experiments for identifying and characterising preferential flow patterns and dominant hydrological processes.

scholarly journals Pore-Scale Transport and Two-Phase Fluid Structures in Fibrous Porous Layers: Application to Fuel Cells and Beyond

2020 ◽  
Author(s):  
Meisam Farzaneh ◽  
Henrik Ström ◽  
Filippo Zanini ◽  
Simone Carmignato ◽  
Srdjan Sasic ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Three Dimensional ◽  
Gas Diffusion ◽  
Macroscopic Model ◽  
Viscous Force ◽  
Pore Scale ◽  
Two Phase ◽  
Flow Paths ◽  
Microscopic Morphology ◽  
Phase Fluid

AbstractWe present pore-scale simulations of two-phase flows in a reconstructed fibrous porous layer. The three-dimensional microstructure of the material, a fuel cell gas diffusion layer, is acquired via X-ray computed tomography and used as input for lattice Boltzmann simulations. We perform a quantitative analysis of the multiphase pore-scale dynamics, and we identify the dominant fluid structures governing mass transport. The results show the existence of three different regimes of transport: a fast inertial dynamics at short times, characterised by a compact uniform front, a viscous-capillary regime at intermediate times, where liquid is transported along a gradually increasing number of preferential flow paths of the size of one–two pores, and a third regime at longer times, where liquid, after having reached the outlet, is exclusively flowing along such flow paths and the two-phase fluid structures are stabilised. We observe that the fibrous layer presents significant variations in its microscopic morphology, which have an important effect on the pore invasion dynamics, and counteract the stabilising viscous force. Liquid transport is indeed affected by the presence of microstructure-induced capillary pressures acting adversely to the flow, leading to capillary fingering transport mechanism and unstable front displacement, even in the absence of hydrophobic treatments of the porous material. We propose a macroscopic model based on an effective contact angle that mimics the effects of the such a dynamic capillary pressure. Finally, we underline the significance of the results for the optimal design of face masks in an effort to mitigate the current COVID-19 pandemic.

scholarly journals Field investigation of preferential fissure flow paths with hydrochemical analysis of small-scale sprinkling experiments

2013 ◽  
Vol 1 (1) ◽  
pp. 637-671 ◽  
Author(s):  
D. M. Krzeminska ◽  
T. A. Bogaard ◽  
T.-H. Debieche ◽  
F. Cervi ◽  
V. Marc ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Unsaturated Zone ◽  
Preferential Flow ◽  
Field Investigation ◽  
Hydrological Processes ◽  
Small Scale ◽  
Flow Paths ◽  
Hydrochemical Analysis ◽  
Preferential Flow Paths ◽  
Spatial Differences

Abstract. The unsaturated zone largely controls groundwater recharge by buffering precipitation but at the same time providing preferential flow paths for infiltration. The importance of preferential flow on landslide hydrology is recognized in literature, but its monitoring and quantification remains difficult. This paper presents a combined hydrological and hydrochemical analysis of small-scale sprinkling experiments with the aim to show the potential of such experiments for studying the spatial differences in dominant hydrological processes within a landslide. This methodology was tested in the highly heterogeneous black marls of the Super-Sauze landslide. The tests were performed in three areas characterised by different displacement rates, surface morphology and local hydrological conditions. Special attention was given to test the potential of small-scale sprinkling experiments to identify and characterise preferential flow patterns and dominating hydrological processes.

Präzisions-Forstwirtschaft – was ist das? | Precision forestry – what's that?

2007 ◽  
Vol 158 (8) ◽  
pp. 235-242 ◽  
Author(s):  
Hans Rudolf Heinimann
Keyword(s):  
Business Processes ◽  
Spatial Scales ◽  
Supply Chain Coordination ◽  
Sensor Technology ◽  
Small Scale ◽  
Soil Physics ◽  
Coordination Problem ◽  
Precision Engineering ◽  
Precision Forestry ◽  
And Control

The term «precision forestry» was first introduced and discussed at a conference in 2001. The aims of this paper are to explore the scientific roots of the precision concept, define «precision forestry», and sketch the challenges that the implementation of this new concept may present to practitioners, educators, and researchers. The term «precision» does not mean accuracy on a small scale, but instead refers to the concurrent coordination and control of processes at spatial scales between 1 m and 100 km. Precision strives for an automatic control of processes. Precision land use differs from precision engineering by the requirements of gathering,storing and managing spatio-temporal variability of site and vegetation parameters. Practitioners will be facing the challenge of designing holistic, standardized business processes that are valid for whole networks of firms,and that follow available standards (e.g., SCOR, WoodX). There is a need to educate and train forestry professionals in the areas of business process re-engineering, computer supported management of business transactions,methods of remote sensing, sensor technology and control theory. Researchers will face the challenge of integrating plant physiology, soil physics and production sciences and solving the supply chain coordination problem (SCCP).

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

scholarly journals Dispersal and Land Cover Contribute to Pseudorabies Virus Exposure in Invasive Wild Pigs

EcoHealth ◽  
2021 ◽  
Author(s):  
Felipe A. Hernández ◽  
Amanda N. Carr ◽  
Michael P. Milleson ◽  
Hunter R. Merrill ◽  
Michael L. Avery ◽  
...  
Keyword(s):  
Land Cover ◽  
Disease Transmission ◽  
Wildlife Conservation ◽  
Pseudorabies Virus ◽  
Spatial Scales ◽  
Information Criterion ◽  
Small Scale ◽  
Wild Pigs ◽  
Bacterial Agent ◽  
Open Canopy

AbstractWe investigated the landscape epidemiology of a globally distributed mammal, the wild pig (Sus scrofa), in Florida (U.S.), where it is considered an invasive species and reservoir to pathogens that impact the health of people, domestic animals, and wildlife. Specifically, we tested the hypothesis that two commonly cited factors in disease transmission, connectivity among populations and abundant resources, would increase the likelihood of exposure to both pseudorabies virus (PrV) and Brucella spp. (bacterial agent of brucellosis) in wild pigs across the Kissimmee Valley of Florida. Using DNA from 348 wild pigs and sera from 320 individuals at 24 sites, we employed population genetic techniques to infer individual dispersal, and an Akaike information criterion framework to compare candidate logistic regression models that incorporated both dispersal and land cover composition. Our findings suggested that recent dispersal conferred higher odds of exposure to PrV, but not Brucella spp., among wild pigs throughout the Kissimmee Valley region. Odds of exposure also increased in association with agriculture and open canopy pine, prairie, and scrub habitats, likely because of highly localized resources within those land cover types. Because the effect of open canopy on PrV exposure reversed when agricultural cover was available, we suggest that small-scale resource distribution may be more important than overall resource abundance. Our results underscore the importance of studying and managing disease dynamics through multiple processes and spatial scales, particularly for non-native pathogens that threaten wildlife conservation, economy, and public health.

scholarly journals FORMULATION OF THE HEAT CONDUCTION EQUATION FOR HETEROGENEOUS MEDIA WITH MULTIPLE SPATIAL SCALES USING REITERATED HOMOGENIZATION

2016 ◽  
Vol 15 (1) ◽  
pp. 96
Author(s):  
E. Iglesias-Rodríguez ◽  
M. E. Cruz ◽  
J. Bravo-Castillero ◽  
R. Guinovart-Díaz ◽  
R. Rodríguez-Ramos ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Small Parameter ◽  
Heat Conduction Equation ◽  
Heterogeneous Media ◽  
Spatial Scales ◽  
Conduction Equation ◽  
Small Scale ◽  
Multiple Spatial Scales ◽  
Effective Coefficients ◽  
Reiterated Homogenization

Heterogeneous media with multiple spatial scales are finding increased importance in engineering. An example might be a large scale, otherwise homogeneous medium filled with dispersed small-scale particles that form aggregate structures at an intermediate scale. The objective in this paper is to formulate the strong-form Fourier heat conduction equation for such media using the method of reiterated homogenization. The phases are assumed to have a perfect thermal contact at the interface. The ratio of two successive length scales of the medium is a constant small parameter ε. The method is an up-scaling procedure that writes the temperature field as an asymptotic multiple-scale expansion in powers of the small parameter ε . The technique leads to two pairs of local and homogenized equations, linked by effective coefficients. In this manner the medium behavior at the smallest scales is seen to affect the macroscale behavior, which is the main interest in engineering. To facilitate the physical understanding of the formulation, an analytical solution is obtained for the heat conduction equation in a functionally graded material (FGM). The approach presented here may serve as a basis for future efforts to numerically compute effective properties of heterogeneous media with multiple spatial scales.

scholarly journals A low-cost technique to measure bank erosion proces ses along middle-size river reaches

2018 ◽  
Author(s):  
Gonzalo Duró ◽  
Alessandra Crosato ◽  
Maarten G. Kleinhans ◽  
Wim S. J. Uijttewaal
Keyword(s):  
Laser Scanning ◽  
Spatial Scales ◽  
Low Cost ◽  
Bank Erosion ◽  
Water Levels ◽  
Small Scale ◽  
Observation Distance ◽  
River Bank ◽  
Erosion Processes ◽  
Rtk Gps

Abstract. Diverse methods are currently available to measure river bank erosion at broad-ranging temporal and spatial scales. Yet, no technique provides low-cost and high-resolution to survey small-scale bank processes along a river reach. We investigate the capabilities of Structure-from-Motion photogrammetry applied with imagery from an Unmanned Aerial Vehicle (UAV) to describe the evolution of riverbank profiles in middle-size rivers. The bank erosion cycle is used as a reference to assess the applicability of different techniques. We surveyed 1.2 km of a restored bank of the Meuse River eight times within a year, combining different photograph perspectives and overlaps to identify an efficient UAV flight to monitor banks. The accuracy of the Digital Surface Models (DSMs) was evaluated compared with RTK GPS points and an Airborne Laser Scanning (ALS) of the whole reach. An oblique perspective with eight photo overlaps was sufficient to achieve the highest relative precision to observation distance of ~1:1400, with 10 cm error range. A complementary nadiral view increased coverage behind bank toe vegetation. The DSM and ALS had comparable accuracies except on banks, where the latter overestimates elevations. Sequential DSMs captured signatures of the erosion cycle such as mass failures, slump-block deposition, and bank undermining. Although this technique requires low water levels and banks without dense vegetation, it is a low-cost method to survey reach-scale riverbanks in sufficient resolution to quantify bank retreat and identify morphological features of the bank failure and erosion processes.

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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