The Experts below are selected from a list of 1836 Experts worldwide ranked by ideXlab platform
Patrick N J Lane - One of the best experts on this subject based on the ideXlab platform.
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modeling the effects of surface storage Macropore Flow and water repellency on infiltration after wildfire
Journal of Hydrology, 2014Co-Authors: Petter Nyman, Gary J Sheridan, Hugh G Smith, Patrick N J LaneAbstract:Summary Wildfires can reduce infiltration capacity of hillslopes by causing (i) extreme soil drying, (ii) increased water repellency and (iii) reduced soil structure. High severity wildfire often results in a non-repellent layer of loose ash and burned soil overlying a water repellent soil matrix. In these conditions the hydraulic parameters vary across discrete layers in the soil profile, making the infiltration process difficult to measure and model. The difficulty is often exacerbated by the discrepancy between actual infiltration processes and the assumptions that underlie commonly used infiltration models, most of which stem from controlled laboratory experiments or agricultural environments, where soils are homogeneous and less variable in space and time than forest soils. This study uses a simple two-layered infiltration model consisting of surface storage (H), Macropore Flow (Kmac) and matrix Flow (Kmat) in order to identify and analyze spatial–temporal infiltration patterns in forest soils recovering from the 2009 Black Saturday wildfires in Victoria, southeast Australia. Infiltration experiments on intact soil cores showed that the soil profile contained a region of strong water repellency that was slow to take on water and inactive in the infiltration process, thus restricting Flow through the matrix. The Flow resistance due to water repellent soil was represented by the minimum critical surface tension (CSTmin) within the top 10 cm of the soil profile. Under field conditions in small headwaters, the CSTmin remained in a water repellent domain throughout a 3-year recovery period, but the strength of water repellency diminished exponentially during wet conditions, resulting in some weather induced temporal variation in steady-state infiltration capacity (Kp). An increasing trend in Macropore availability during recovery was the main source of temporal variability in Kp during the study period, indicating (in accordance with previous studies) that Macropore Flow dominates infiltration processes in these forest soils. Storage in ash and burned surface soil after wildfire was initially high (∼4 mm), then declined exponentially with time since fire. Overall the study showed that the two layered soil can be represented and parameterized by partitioning the infiltration process into surface storage and Flow through a partially saturated and restrictive soil layer. Ash, water repellency and Macropore Flow are key characteristics of burned forest soils in general, and the proposed model may therefore be a useful tool for characterizing fire impact and recovery in other systems.
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synergistic effects of water repellency and Macropore Flow on the hydraulic conductivity of a burned forest soil south east australia
Hydrological Processes, 2010Co-Authors: Petter Nyman, Gary J Sheridan, Patrick N J LaneAbstract:Research shows that water repellency is a key hydraulic property that results in reduced infiltration rates in burned soils. However, more work is required in order to link the hydrological behaviour of water repellent soils to observed runoff responses at the plot and hillslope scale. This study used 5 M ethanol and water in disc infiltrometers to quantify the role of Macropore Flow and water repellency on spatial and temporal infiltration patterns in a burned soil at plot ( 0.5 mm), comprising just 5.5% of the soil volume, contributed to 70% and 95%, respectively, of the field-saturated and ponded hydraulic conductivity (K p ). Because Flow occurred almost entirely via Macropores in non-repellent areas, this meant that less than 2.5% of the soil surface effectively contributed to infiltration. The hydraulic conductivity increased by a factor of up to 2.5 as the hydraulic head increased from 0 to 5 mm. Due to the synergistic effect of Macropore Flow and water repellency, the coefficient of variation (CV) in K p was three times higher in the water-repellent soil (CV = 175%) than under the simulated non-repellent conditions (CV = 66%). The high spatial variability in K p would act to reduce the effective infiltration rate during runoff generation at plot scale. Ponding, which tend to increase with increasing scale, activates Flow through Macropores and would raise the effective infiltration rates at larger scales. Field experiments designed to provide representative measurements of infiltration after fire in these systems must therefore consider both the inherent variability in hydraulic conductivity and the variability in infiltration caused by interactions between surface runoff and hydraulic conductivity. Copyright © 2010 John Wiley & Sons, Ltd.
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Synergistic effects of water repellency and Macropore Flow on the hydraulic conductivity of a burned forest soil, south‐east Australia
Hydrological Processes, 2010Co-Authors: Petter Nyman, Gary Sheridan, Patrick N J LaneAbstract:Research shows that water repellency is a key hydraulic property that results in reduced infiltration rates in burned soils. However, more work is required in order to link the hydrological behaviour of water repellent soils to observed runoff responses at the plot and hillslope scale. This study used 5 M ethanol and water in disc infiltrometers to quantify the role of Macropore Flow and water repellency on spatial and temporal infiltration patterns in a burned soil at plot ( 0.5 mm), comprising just 5.5% of the soil volume, contributed to 70% and 95%, respectively, of the field-saturated and ponded hydraulic conductivity (K p ). Because Flow occurred almost entirely via Macropores in non-repellent areas, this meant that less than 2.5% of the soil surface effectively contributed to infiltration. The hydraulic conductivity increased by a factor of up to 2.5 as the hydraulic head increased from 0 to 5 mm. Due to the synergistic effect of Macropore Flow and water repellency, the coefficient of variation (CV) in K p was three times higher in the water-repellent soil (CV = 175%) than under the simulated non-repellent conditions (CV = 66%). The high spatial variability in K p would act to reduce the effective infiltration rate during runoff generation at plot scale. Ponding, which tend to increase with increasing scale, activates Flow through Macropores and would raise the effective infiltration rates at larger scales. Field experiments designed to provide representative measurements of infiltration after fire in these systems must therefore consider both the inherent variability in hydraulic conductivity and the variability in infiltration caused by interactions between surface runoff and hydraulic conductivity. Copyright © 2010 John Wiley & Sons, Ltd.
Petter Nyman - One of the best experts on this subject based on the ideXlab platform.
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modeling the effects of surface storage Macropore Flow and water repellency on infiltration after wildfire
Journal of Hydrology, 2014Co-Authors: Petter Nyman, Gary J Sheridan, Hugh G Smith, Patrick N J LaneAbstract:Summary Wildfires can reduce infiltration capacity of hillslopes by causing (i) extreme soil drying, (ii) increased water repellency and (iii) reduced soil structure. High severity wildfire often results in a non-repellent layer of loose ash and burned soil overlying a water repellent soil matrix. In these conditions the hydraulic parameters vary across discrete layers in the soil profile, making the infiltration process difficult to measure and model. The difficulty is often exacerbated by the discrepancy between actual infiltration processes and the assumptions that underlie commonly used infiltration models, most of which stem from controlled laboratory experiments or agricultural environments, where soils are homogeneous and less variable in space and time than forest soils. This study uses a simple two-layered infiltration model consisting of surface storage (H), Macropore Flow (Kmac) and matrix Flow (Kmat) in order to identify and analyze spatial–temporal infiltration patterns in forest soils recovering from the 2009 Black Saturday wildfires in Victoria, southeast Australia. Infiltration experiments on intact soil cores showed that the soil profile contained a region of strong water repellency that was slow to take on water and inactive in the infiltration process, thus restricting Flow through the matrix. The Flow resistance due to water repellent soil was represented by the minimum critical surface tension (CSTmin) within the top 10 cm of the soil profile. Under field conditions in small headwaters, the CSTmin remained in a water repellent domain throughout a 3-year recovery period, but the strength of water repellency diminished exponentially during wet conditions, resulting in some weather induced temporal variation in steady-state infiltration capacity (Kp). An increasing trend in Macropore availability during recovery was the main source of temporal variability in Kp during the study period, indicating (in accordance with previous studies) that Macropore Flow dominates infiltration processes in these forest soils. Storage in ash and burned surface soil after wildfire was initially high (∼4 mm), then declined exponentially with time since fire. Overall the study showed that the two layered soil can be represented and parameterized by partitioning the infiltration process into surface storage and Flow through a partially saturated and restrictive soil layer. Ash, water repellency and Macropore Flow are key characteristics of burned forest soils in general, and the proposed model may therefore be a useful tool for characterizing fire impact and recovery in other systems.
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synergistic effects of water repellency and Macropore Flow on the hydraulic conductivity of a burned forest soil south east australia
Hydrological Processes, 2010Co-Authors: Petter Nyman, Gary J Sheridan, Patrick N J LaneAbstract:Research shows that water repellency is a key hydraulic property that results in reduced infiltration rates in burned soils. However, more work is required in order to link the hydrological behaviour of water repellent soils to observed runoff responses at the plot and hillslope scale. This study used 5 M ethanol and water in disc infiltrometers to quantify the role of Macropore Flow and water repellency on spatial and temporal infiltration patterns in a burned soil at plot ( 0.5 mm), comprising just 5.5% of the soil volume, contributed to 70% and 95%, respectively, of the field-saturated and ponded hydraulic conductivity (K p ). Because Flow occurred almost entirely via Macropores in non-repellent areas, this meant that less than 2.5% of the soil surface effectively contributed to infiltration. The hydraulic conductivity increased by a factor of up to 2.5 as the hydraulic head increased from 0 to 5 mm. Due to the synergistic effect of Macropore Flow and water repellency, the coefficient of variation (CV) in K p was three times higher in the water-repellent soil (CV = 175%) than under the simulated non-repellent conditions (CV = 66%). The high spatial variability in K p would act to reduce the effective infiltration rate during runoff generation at plot scale. Ponding, which tend to increase with increasing scale, activates Flow through Macropores and would raise the effective infiltration rates at larger scales. Field experiments designed to provide representative measurements of infiltration after fire in these systems must therefore consider both the inherent variability in hydraulic conductivity and the variability in infiltration caused by interactions between surface runoff and hydraulic conductivity. Copyright © 2010 John Wiley & Sons, Ltd.
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Synergistic effects of water repellency and Macropore Flow on the hydraulic conductivity of a burned forest soil, south‐east Australia
Hydrological Processes, 2010Co-Authors: Petter Nyman, Gary Sheridan, Patrick N J LaneAbstract:Research shows that water repellency is a key hydraulic property that results in reduced infiltration rates in burned soils. However, more work is required in order to link the hydrological behaviour of water repellent soils to observed runoff responses at the plot and hillslope scale. This study used 5 M ethanol and water in disc infiltrometers to quantify the role of Macropore Flow and water repellency on spatial and temporal infiltration patterns in a burned soil at plot ( 0.5 mm), comprising just 5.5% of the soil volume, contributed to 70% and 95%, respectively, of the field-saturated and ponded hydraulic conductivity (K p ). Because Flow occurred almost entirely via Macropores in non-repellent areas, this meant that less than 2.5% of the soil surface effectively contributed to infiltration. The hydraulic conductivity increased by a factor of up to 2.5 as the hydraulic head increased from 0 to 5 mm. Due to the synergistic effect of Macropore Flow and water repellency, the coefficient of variation (CV) in K p was three times higher in the water-repellent soil (CV = 175%) than under the simulated non-repellent conditions (CV = 66%). The high spatial variability in K p would act to reduce the effective infiltration rate during runoff generation at plot scale. Ponding, which tend to increase with increasing scale, activates Flow through Macropores and would raise the effective infiltration rates at larger scales. Field experiments designed to provide representative measurements of infiltration after fire in these systems must therefore consider both the inherent variability in hydraulic conductivity and the variability in infiltration caused by interactions between surface runoff and hydraulic conductivity. Copyright © 2010 John Wiley & Sons, Ltd.
P E Cuadra - One of the best experts on this subject based on the ideXlab platform.
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phosphorus dynamics in tile drain Flow during storms in the us midwest
Agricultural Water Management, 2011Co-Authors: Philippe Vidon, P E CuadraAbstract:Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006-0.025Â mg/L for SRP and 0.057-0.176Â mg/L for TP. For large storms (>6Â cm bulk precipitation), for which Macropore Flow represented between 43 and 50% of total tile-drain Flow, SRP transport to tile-drains was primarily regulated by Macropore Flow. For smaller tile-Flow generating events ( 6Â cm bulk precipitation). Although significant variations in tile-Flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of Macropore Flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management.
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Phosphorus dynamics in tile-drain Flow during storms in the US Midwest
Agricultural Water Management, 2011Co-Authors: Philippe Vidon, P E CuadraAbstract:Abstract Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006–0.025 mg/L for SRP and 0.057–0.176 mg/L for TP. For large storms (>6 cm bulk precipitation), for which Macropore Flow represented between 43 and 50% of total tile-drain Flow, SRP transport to tile-drains was primarily regulated by Macropore Flow. For smaller tile-Flow generating events ( −2 /storm) and TP (0.10–8.64 mg m −2 /storm) export rates were extremely variable and positively significantly correlated to both mean discharge and bulk precipitation. Soluble reactive P accounted for 9.9–15.5% of TP fluxes for small tile-Flow generating events ( 6 cm bulk precipitation). Although significant variations in tile-Flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of Macropore Flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management.
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Impact of precipitation characteristics on soil hydrology in tile-drained landscapes
Hydrological Processes, 2010Co-Authors: Philippe Vidon, P E CuadraAbstract:Understanding the variables regulating tile-Flow response to precipitation in the US Midwest is critical for water quality management. This study (1) investigates the relationship between precipitation characteristics, antecedent water table depth and tile-Flow response at a high temporal resolution during storms; and (2) determines the relative importance of Macropore Flow versus matrix Flow in tile Flow in a tile-drained soya bean field in Indiana. In spring, although variations in antecedent water table depth imparted some variation in tile-Flow response to precipitation, bulk precipitation was the best predictor of mean tile Flow, maximum tile Flow, time to peak, and run-off ratio. The contribution of Macropore Flow to total Flow significantly increased with precipitation amount, and Macropore Flow represented between 11 and 50% of total drain Flow, with peak contributions between 15 and 74% of Flow. For large storms (>6 cm bulk precipitation), cations data indicated a dilution of groundwater with new water as discharge peaked. Although no clear dilution or concentration patterns for Mg2+ or K+ were observed for smaller tile Flow generating events (
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Impact of precipitation characteristics on soil hydrology in tile‐drained landscapes
Hydrological Processes, 2010Co-Authors: Philippe Vidon, P E CuadraAbstract:Understanding the variables regulating tile-Flow response to precipitation in the US Midwest is critical for water quality management. This study (1) investigates the relationship between precipitation characteristics, antecedent water table depth and tile-Flow response at a high temporal resolution during storms; and (2) determines the relative importance of Macropore Flow versus matrix Flow in tile Flow in a tile-drained soya bean field in Indiana. In spring, although variations in antecedent water table depth imparted some variation in tile-Flow response to precipitation, bulk precipitation was the best predictor of mean tile Flow, maximum tile Flow, time to peak, and run-off ratio. The contribution of Macropore Flow to total Flow significantly increased with precipitation amount, and Macropore Flow represented between 11 and 50% of total drain Flow, with peak contributions between 15 and 74% of Flow. For large storms (>6 cm bulk precipitation), cations data indicated a dilution of groundwater with new water as discharge peaked. Although no clear dilution or concentration patterns for Mg2+ or K+ were observed for smaller tile Flow generating events (
Philippe Vidon - One of the best experts on this subject based on the ideXlab platform.
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phosphorus dynamics in tile drain Flow during storms in the us midwest
Agricultural Water Management, 2011Co-Authors: Philippe Vidon, P E CuadraAbstract:Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006-0.025Â mg/L for SRP and 0.057-0.176Â mg/L for TP. For large storms (>6Â cm bulk precipitation), for which Macropore Flow represented between 43 and 50% of total tile-drain Flow, SRP transport to tile-drains was primarily regulated by Macropore Flow. For smaller tile-Flow generating events ( 6Â cm bulk precipitation). Although significant variations in tile-Flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of Macropore Flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management.
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Phosphorus dynamics in tile-drain Flow during storms in the US Midwest
Agricultural Water Management, 2011Co-Authors: Philippe Vidon, P E CuadraAbstract:Abstract Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006–0.025 mg/L for SRP and 0.057–0.176 mg/L for TP. For large storms (>6 cm bulk precipitation), for which Macropore Flow represented between 43 and 50% of total tile-drain Flow, SRP transport to tile-drains was primarily regulated by Macropore Flow. For smaller tile-Flow generating events ( −2 /storm) and TP (0.10–8.64 mg m −2 /storm) export rates were extremely variable and positively significantly correlated to both mean discharge and bulk precipitation. Soluble reactive P accounted for 9.9–15.5% of TP fluxes for small tile-Flow generating events ( 6 cm bulk precipitation). Although significant variations in tile-Flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of Macropore Flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management.
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Impact of precipitation characteristics on soil hydrology in tile-drained landscapes
Hydrological Processes, 2010Co-Authors: Philippe Vidon, P E CuadraAbstract:Understanding the variables regulating tile-Flow response to precipitation in the US Midwest is critical for water quality management. This study (1) investigates the relationship between precipitation characteristics, antecedent water table depth and tile-Flow response at a high temporal resolution during storms; and (2) determines the relative importance of Macropore Flow versus matrix Flow in tile Flow in a tile-drained soya bean field in Indiana. In spring, although variations in antecedent water table depth imparted some variation in tile-Flow response to precipitation, bulk precipitation was the best predictor of mean tile Flow, maximum tile Flow, time to peak, and run-off ratio. The contribution of Macropore Flow to total Flow significantly increased with precipitation amount, and Macropore Flow represented between 11 and 50% of total drain Flow, with peak contributions between 15 and 74% of Flow. For large storms (>6 cm bulk precipitation), cations data indicated a dilution of groundwater with new water as discharge peaked. Although no clear dilution or concentration patterns for Mg2+ or K+ were observed for smaller tile Flow generating events (
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Impact of precipitation characteristics on soil hydrology in tile‐drained landscapes
Hydrological Processes, 2010Co-Authors: Philippe Vidon, P E CuadraAbstract:Understanding the variables regulating tile-Flow response to precipitation in the US Midwest is critical for water quality management. This study (1) investigates the relationship between precipitation characteristics, antecedent water table depth and tile-Flow response at a high temporal resolution during storms; and (2) determines the relative importance of Macropore Flow versus matrix Flow in tile Flow in a tile-drained soya bean field in Indiana. In spring, although variations in antecedent water table depth imparted some variation in tile-Flow response to precipitation, bulk precipitation was the best predictor of mean tile Flow, maximum tile Flow, time to peak, and run-off ratio. The contribution of Macropore Flow to total Flow significantly increased with precipitation amount, and Macropore Flow represented between 11 and 50% of total drain Flow, with peak contributions between 15 and 74% of Flow. For large storms (>6 cm bulk precipitation), cations data indicated a dilution of groundwater with new water as discharge peaked. Although no clear dilution or concentration patterns for Mg2+ or K+ were observed for smaller tile Flow generating events (
Gary J Sheridan - One of the best experts on this subject based on the ideXlab platform.
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modeling the effects of surface storage Macropore Flow and water repellency on infiltration after wildfire
Journal of Hydrology, 2014Co-Authors: Petter Nyman, Gary J Sheridan, Hugh G Smith, Patrick N J LaneAbstract:Summary Wildfires can reduce infiltration capacity of hillslopes by causing (i) extreme soil drying, (ii) increased water repellency and (iii) reduced soil structure. High severity wildfire often results in a non-repellent layer of loose ash and burned soil overlying a water repellent soil matrix. In these conditions the hydraulic parameters vary across discrete layers in the soil profile, making the infiltration process difficult to measure and model. The difficulty is often exacerbated by the discrepancy between actual infiltration processes and the assumptions that underlie commonly used infiltration models, most of which stem from controlled laboratory experiments or agricultural environments, where soils are homogeneous and less variable in space and time than forest soils. This study uses a simple two-layered infiltration model consisting of surface storage (H), Macropore Flow (Kmac) and matrix Flow (Kmat) in order to identify and analyze spatial–temporal infiltration patterns in forest soils recovering from the 2009 Black Saturday wildfires in Victoria, southeast Australia. Infiltration experiments on intact soil cores showed that the soil profile contained a region of strong water repellency that was slow to take on water and inactive in the infiltration process, thus restricting Flow through the matrix. The Flow resistance due to water repellent soil was represented by the minimum critical surface tension (CSTmin) within the top 10 cm of the soil profile. Under field conditions in small headwaters, the CSTmin remained in a water repellent domain throughout a 3-year recovery period, but the strength of water repellency diminished exponentially during wet conditions, resulting in some weather induced temporal variation in steady-state infiltration capacity (Kp). An increasing trend in Macropore availability during recovery was the main source of temporal variability in Kp during the study period, indicating (in accordance with previous studies) that Macropore Flow dominates infiltration processes in these forest soils. Storage in ash and burned surface soil after wildfire was initially high (∼4 mm), then declined exponentially with time since fire. Overall the study showed that the two layered soil can be represented and parameterized by partitioning the infiltration process into surface storage and Flow through a partially saturated and restrictive soil layer. Ash, water repellency and Macropore Flow are key characteristics of burned forest soils in general, and the proposed model may therefore be a useful tool for characterizing fire impact and recovery in other systems.
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synergistic effects of water repellency and Macropore Flow on the hydraulic conductivity of a burned forest soil south east australia
Hydrological Processes, 2010Co-Authors: Petter Nyman, Gary J Sheridan, Patrick N J LaneAbstract:Research shows that water repellency is a key hydraulic property that results in reduced infiltration rates in burned soils. However, more work is required in order to link the hydrological behaviour of water repellent soils to observed runoff responses at the plot and hillslope scale. This study used 5 M ethanol and water in disc infiltrometers to quantify the role of Macropore Flow and water repellency on spatial and temporal infiltration patterns in a burned soil at plot ( 0.5 mm), comprising just 5.5% of the soil volume, contributed to 70% and 95%, respectively, of the field-saturated and ponded hydraulic conductivity (K p ). Because Flow occurred almost entirely via Macropores in non-repellent areas, this meant that less than 2.5% of the soil surface effectively contributed to infiltration. The hydraulic conductivity increased by a factor of up to 2.5 as the hydraulic head increased from 0 to 5 mm. Due to the synergistic effect of Macropore Flow and water repellency, the coefficient of variation (CV) in K p was three times higher in the water-repellent soil (CV = 175%) than under the simulated non-repellent conditions (CV = 66%). The high spatial variability in K p would act to reduce the effective infiltration rate during runoff generation at plot scale. Ponding, which tend to increase with increasing scale, activates Flow through Macropores and would raise the effective infiltration rates at larger scales. Field experiments designed to provide representative measurements of infiltration after fire in these systems must therefore consider both the inherent variability in hydraulic conductivity and the variability in infiltration caused by interactions between surface runoff and hydraulic conductivity. Copyright © 2010 John Wiley & Sons, Ltd.
