scholarly journals An Innovative Approach for Locating and Evaluating Subsurface Pathways for Nitrogen Loss

2001 ◽  
Vol 1 ◽  
pp. 223-229 ◽  
Author(s):  
C.L. Walthall ◽  
T.J. Gish ◽  
C.S.T. Daughtry ◽  
W.P. Dulaney ◽  
K.-J.S. Kung ◽  
...  
Keyword(s):  
Management Practices ◽  
Preferential Flow ◽  
Agricultural Research ◽  
Nitrogen Loss ◽  
Flow Behavior ◽  
Chemical Contamination ◽  
Riparian Wetland ◽  
Flow Pathways ◽  
Preferential Flow Pathways

Fundamental watershed-scale processes governing chemical flux to neighboring ecosystems are so poorly understood that effective strategies for mitigating chemical contamination cannot be formulated. Characterization of evapotranspiration, surface runoff, plant uptake, subsurface preferential flow, behavior of the chemicals in neighboring ecosystems, and an understanding of how crop management practices influence these processes are needed. Adequate characterization of subsurface flow has been especially difficult because conventional sampling methods are ineffective for measuring preferential flow of water and solutes. A sampling strategy based on ground-penetrating radar (GPR) mapping of subsurface structures coupled with near real-time soil moisture data, surface topography, remotely sensed imagery, and a geographic information system (GIS) appears to offer a means of accurately identifying subsurface preferential flow pathways. Four small adjacent watersheds draining into a riparian wetland and first-order stream at the USDA-ARS Beltsville Agricultural Research Center, Beltsville, MD are being studied with this protocol. The spatial location of some preferential flow pathways for chemicals exiting these agricultural watersheds to the neighboring ecosystems have been identified. Confirmation of the pathways is via examination of patterns in yield monitor data and remote sensing imagery.

scholarly journals The role of heterogeneous lithology in a glaciofluvial deposit on unsaturated preferential flow – a numerical study

2017 ◽  
Vol 65 (3) ◽  
pp. 209-221 ◽  
Author(s):  
Erij Ben Slimene ◽  
Laurent Lassabatere ◽  
Jiří Šimůnek ◽  
Thierry Winiarski ◽  
Remy Gourdon
Keyword(s):  
Urban Areas ◽  
Hydraulic Properties ◽  
Preferential Flow ◽  
Numerical Study ◽  
Full Characterization ◽  
Capillary Barriers ◽  
Flow Pathways ◽  
Preferential Flow Pathways

AbstractAn understanding of preferential flow in the vadose zone is crucial for the prediction of the fate of pollutants. Infiltration basins, developed to mitigate the adverse effects of impervious surfaces in urban areas, are established above strongly heterogeneous and highly permeable deposits and thus are prone to preferential flow and enhanced pollutant transport. This study numerically investigates the establishment of preferential flow in an infiltration basin in the Lyon suburbs (France) established over a highly heterogeneous glaciofluvial deposit covering much of the Lyon region. An investigation of the soil transect (13.5 m long and 2.5 m deep) provided full characterization of lithology and hydraulic properties of present lithofacies. Numerical modeling with the HYDRUS-2D model of water flow in the transect was used to identify the effects of individual lithofacies that constitute the deposit. Multiple scenarios that considered different levels of heterogeneity were evaluated. Preferential flow was studied for several values of infiltration rates applied after a long dry period. The numerical study shows that the high contrast in hydraulic properties of different lithofacies triggers the establishment of preferential flow (capillary barriers and funneled flow). Preferential flow develops mainly for low water fluxes imposed at the surface. The role of individual lithofacies in triggering preferential flow depends on their shapes (layering versus inclusions) and their sizes. While lenses and inclusions produce preferential flow pathways, the presence of the surface layer has no effect on the development of preferential flow and it only affects the effective hydraulic conductivity of the heterogeneous transect.

scholarly journals Detecting infiltrated water and preferential flow pathways through time-lapse ground-penetrating radar surveys

2020 ◽  
Vol 726 ◽  
pp. 138511 ◽  
Author(s):  
Simone Di Prima ◽  
Thierry Winiarski ◽  
Rafael Angulo-Jaramillo ◽  
Ryan D. Stewart ◽  
Mirko Castellini ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Preferential Flow ◽  
Time Lapse ◽  
Flow Pathways ◽  
Preferential Flow Pathways ◽  
Ground Penetrating

scholarly journals A Mathematical Model of Gas and Water Flow in a Swelling Geomaterial—Part 2. Process Simulation

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 32 ◽  
Author(s):  
Elias Ernest Dagher ◽  
Julio Ángel Infante Sedano ◽  
Thanh Son Nguyen
Keyword(s):  
Mathematical Model ◽  
Preferential Flow ◽  
Expansive Soils ◽  
Flow Behavior ◽  
Slip Flow ◽  
Cylindrical Sample ◽  
Two Phase ◽  
Flow Pathways ◽  
Permeable Soil

Gases can potentially generate in a deep geological repository (DGR) for the long-term containment of radioactive waste. Natural and engineered barriers provide containment of the waste by mitigating contaminant migration. However, if gas pressures exceed the mechanical strength of these barriers, preferential flow pathways for both the gases and the porewater could form, providing a source of potential exposure to people and the environment. Expansive soils, such as bentonite-based materials, are widely considered as sealing materials. Understanding the long-term performance of these seals as barriers against gas migration is an important component in the design and the long-term safety assessment of a DGR. This study proposes a hydro-mechanical mathematical model for migration of gas through a low-permeable swelling geomaterial based on the theoretical framework of poromechanics. Using the finite element method, the model is used to simulate 1D flow through a confined cylindrical sample of near-saturated low-permeable soil under a constant volume boundary stress condition. The study expands upon previous work by the authors by assessing the influence of heterogeneity, the Klinkenberg “slip flow” effect, and a swelling stress on flow behavior. Based on the results, this study provides fundamental insight into a number of factors that may influence two-phase flow.

scholarly journals Phosphorus in Preferential Flow Pathways of Forest Soils in Germany

Forests ◽  
2016 ◽  
Vol 8 (1) ◽  
pp. 19 ◽  
Author(s):  
Dorit Julich ◽  
Stefan Julich ◽  
Karl-Heinz Feger
Keyword(s):  
Forest Soils ◽  
Preferential Flow ◽  
Flow Pathways ◽  
Preferential Flow Pathways
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