Renato Morbidelli | University of Perugia, Italy (original) (raw)
Papers by Renato Morbidelli
Acta Geophysica, Feb 10, 2018
Journal of Hydrology, 2020
Hydrological Sciences Journal-journal Des Sciences Hydrologiques, 2004
ABSTRACT Abstract The role of accuracy in the representation of infiltration on the effectiveness... more ABSTRACT Abstract The role of accuracy in the representation of infiltration on the effectiveness ofreal-time flood forecasting models ,was investigated. A simple ,semi-distributed model of conceptual,type with adaptive estimate of hydraulic,characteristics included inthe,infiltration component ,was ,selected. Infiltration was ,described by a ,very accurate approach recently formulated for complex rainfall patterns, or alternatively through a simpler,formulation known ,as an,extension of the classical time compres- sion approximation. The results indicated that, for situations involving a significant rainfall variability in space, the inaccuracy in the representation of infiltration cannot becorrected,by the ,adaptive component ,of the rainfall–runoff model. A preliminary analysis of the role of an approximation,of saturated hydraulic conductivity to be used ineach,homogeneous ,area of the semi-distributed model ,used both in non-adaptive version and in real-time is also presented. Key words rainfall–runoff;floods; infiltration; hillslope hydrology Prévision de crue et modélisation de l’infiltration
Global warming is affecting hydroclimatic parameters determining changes in temperature and preci... more Global warming is affecting hydroclimatic parameters determining changes in temperature and precipitation patterns. In addition, human-induced activities act on the land use and land cover (LULC) features of catchments. Runoff generation can be affected by these factors in both natural and anthropogenic basins. The aim of the current study is to investigate the relationship between the runoff coefficient (Rc), computed by exploiting long-term rainfall and streamflow records, and several features that can potentially affect it, namely meteorological parameters, soil water storage (SWS), and LULC changes through the wavelet coherence analysis. The method has been applied over the Upper Tiber basin at Ponte Nuovo outlet, in central Italy. To facilitate the understanding of the current catchment conditions in terms of surface water availability, a trend analysis has been performed using the Mann-Kendall (MK) test. For the long-term period of 1927-2020, the results reveal a decreasing trend of Rc. In addition, the MK test for seasonal temperature and SWS shows increasing and decreasing trends, respectively. Based on the wavelet analysis, a significant positive correlation is observed between Rc and SWS in the annual cycle with a phase shift of less than one month, while a strong negative correlation is observed between Rc and temperature in the annual period with a phase shift of 3-6 months. The study of the relationship between Rc and LULC changes shows a weak correlation. The lower phase shift between Rc and SWS indicate that Rc is susceptible to SWS in a faster way than other components. These results allows a better understanding of the main factors influencing the Rc over the pilot area; moreover, an extension to other Mediterranean basins is foreseen as a follow-up of this work.
Journal of Hydrology, 1998
A model which couples the kinematic wave approximation for Hortonian overland flow and the concep... more A model which couples the kinematic wave approximation for Hortonian overland flow and the conceptual approach developed by Corradini et al. (1997) [J. Hydrol., 192, 104-124] for local infiltration was used to investigate the effects of random spatial variability of saturated hydraulic conductivity, Ks, on the outflow hydrograph at hillslope scale. The model incorporates a representation of infiltration of overland flow running over pervious downstream areas ("run-on" process). Single rainfall pulses and complex storms over two soils, representative of a silty loam and a sandy loam soil, were considered. Our results suggest that for realistic values of the coefficient of variation of Ks the run-on process cannot be disregarded, because it produces a significant decrease of overland flow during both the rising and the recession limb of the hydrograph. Furthermore, the role of the level of spatial correlation of Ks was found to be typically minor and the run-on process concurred to this result. The possibility of simplifying the stochastic problem by a deterministic approach based on the use of a uniform lumped value of Ks was also examined and rainfall patterns adequate for this simplification were deduced in terms of scaled storm intensity and storm duration.
Natural Hazards, Feb 10, 2021
Analyses of historical records of landslides and climate variables are useful tools to search for... more Analyses of historical records of landslides and climate variables are useful tools to search for correlations between damaging landslide events and their triggers. In this work, we investigate the temporal and geographical relationships between two long-term historical series of catalogued landslide occurrences and daily rainfall data in Umbria, a central Italian region, from 1928 to 2001. Moreover, we search for changes in the frequency and density of landslides, and in the characteristics of the associated rainfall events. Using a consolidated approach, partially modified, we find that the rainfall events that have produced rainfall-induced landslides in Umbria changed in space and time during observation period and between two considered sub-periods (1928–1975 and 1976–2001). In particular, we find that: (i) the monthly distribution of landslides associated with rainfall events is quite different than that of all landslides in the regional catalogue; (ii) the spatial and temporal distribution of REL changed from the older (most events occurred in winter) to the recent period (most events occurred in autumn); (iii) the recent most rainfall events associated with landslides are characterized by a lower cumulated rainfall and a shorter duration, sign of an increased propensity of the regional territory to produce landslides over time.
Hydrological Processes, 2006
This study first explores the role of spatial heterogeneity, in both the saturated hydraulic cond... more This study first explores the role of spatial heterogeneity, in both the saturated hydraulic conductivity Ks and rainfall intensity r, on the integrated hydrological response of a natural slope. On this basis, a mathematical model for estimating the expected areal-average infiltration is then formulated. Both Ks and r are considered as random variables with assessed probability density functions. The model
CRC Press eBooks, Nov 16, 2006
Hydrological Sciences Journal-journal Des Sciences Hydrologiques, Apr 1, 2004
The role of accuracy in the representation of infiltration on the effectiveness of real-time floo... more The role of accuracy in the representation of infiltration on the effectiveness of real-time flood forecasting models was investigated. A simple semi-distributed model of conceptual type with adaptive estimate of hydraulic characteristics included in the infiltration component was selected. Infiltration was described by a very accurate approach recently formulated for complex rainfall patterns, or alternatively through a simpler formulation known as an extension of the classical time compression approximation. The results indicated that, for situations involving a significant rainfall variability in space, the inaccuracy in the representation of infiltration cannot be corrected by the adaptive component of the rainfall-runoff model. A preliminary analysis of the role of an approximation of saturated hydraulic conductivity to be used in each homogeneous area of the semi-distributed model used both in non-adaptive version and in real-time is also presented.
Journal of Hydrologic Engineering, Apr 1, 1999
ABSTRACT This study investigated the use of similarity profiles in space for analyzing surface-ru... more ABSTRACT This study investigated the use of similarity profiles in space for analyzing surface-runoff hydrographs occurring at the outlet of small watersheds. The spatial behavior of the flow depth over each element (overland region or stream reach) was approximated by a sine function, so that the partial differential equations governing water movement were reduced to ordinary differential equations. Solutions of these reduced equations were obtained at a smaller computational cost, with analytical solutions available in some cases. These solutions then were extended to study surface water movement over small watersheds that could be represented as a sequence of cascading overland flow planes and streams. The performance of this model was studied by comparing with results from another physically based model, KINEROS, and experimental observations. It was concluded that the similarity solutions are robust and almost as accurate as numerical solutions that were obtained from physically based models, when used within their range of applicability explicitly defined in the paper. Some guidelines for spatial discretization of the watershed for appropriate use of the similarity solutions have been provided.
Journal of Hydrologic Engineering, Dec 1, 2008
ABSTRACT This paper describes laboratory experiments that provide evidence of infiltration of exc... more ABSTRACT This paper describes laboratory experiments that provide evidence of infiltration of excess runoff water from upstream areas that moves downslope over unsaturated areas (run-on process). The experiments were carried out using a tilting tank that was packed with two different natural soils to a depth of 70 cm and subjected to artificial rainfalls from a rainfall simulator. Different rainfall patterns were generated over the surface at different slope settings. Measurements of overland flow, deep flow, and soil water content, together with photographs of soil surface, were used to quantify the main features of the run-on process. The results indicate that the interaction between Hortonian overland flow and local infiltration over the permeable areas can be appropriately described by representing the flow depth per unit time as an "additional" rainfall rate. Thus, these experimental results support the representation of the run-on process that was adopted in previous numerical studies that evaluated the effects of the run-on process.
Hydrological Processes, 2002
Two models for estimating expected areal‐average infiltration rate, Ī, at the hillslope scale are... more Two models for estimating expected areal‐average infiltration rate, Ī, at the hillslope scale are presented. The first relies upon the condition of a negligible infiltration of surface water running downslope (run‐on process) into a previous heterogeneous soil. It is an adapted version of an earlier semi‐analytical model. The second incorporates the run‐on process and is based on a lumped approach that uses an effective saturated hydraulic conductivity. This latter was parameterized in terms of the main characteristics of rainfall and soil. Both the models were tested by comparison with the results carried out by Monte‐Carlo simulations over different soil types. It was found that the first model simulated Ī with maximum errors in magnitude typically less than 10%. The second model provided similar errors in the total volume of overland flow, and the rising limb of the hydrograph experienced a distortion. Lastly, satisfactory results were obtained by comparing the model without run‐on with an empirical approach particularly accurate for fine‐textured soils. Copyright © 2002 John Wiley & Sons, Ltd.
Journal of Hydrology, 2006
A semi-analytical model for the estimate of expected areal-average infiltration rate at hillslope... more A semi-analytical model for the estimate of expected areal-average infiltration rate at hillslope scale is presented. It accounts for spatial heterogeneity of the saturated hydraulic conductivity, K s , and rainfall rate, r. The K s field is characterized by a lognormal probability density function while the rainfall rate r is represented by a uniform distribution between two extreme values. The model formulation relies upon the use of cumulative infiltration as the independent variable which is then expressed as a function of an expected time for use in practical applications. The solution is applicable for those ranges of r and K s that allow for neglecting the infiltration of surface water running downslope into pervious soils (run-on process). The model was tested by comparisons with Monte Carlo simulations carried out for a variety of coefficients of variation of r and K s over a clay loam soil and a sandy loam soil. The model was found to be very reliable both with coupled spatial variability of r and K s and when only one variable is characterized by spatial heterogeneity while the other is uniform.
Journal of Hydrology, Jul 1, 2009
Summary Infiltration and deep flow on sloping surfaces were studied by combining controlled labor... more Summary Infiltration and deep flow on sloping surfaces were studied by combining controlled laboratory experiments with mathematical models. Experimental variables included soil types, rainfall intensities, and surface slopes. Preliminary analyses of the data indicated that increased slope has a positive influence on surface flow, and that this influence increases relatively with decreasing rainfall rate. However, current theories could not adequately explain the observed behavior of deep and surface flows for varying slopes. Three mathematical models of varying complexity were employed to supplement the experimental results. These models were (i) the 2-D Hydrus numerical model, (ii) numerical solution of 1-D saturated–unsaturated flow equation on sloping surfaces, and (iii) a simplified 1-D sharp-front model for sloping surfaces. For the latter two models, a surface flow component based on the kinematic wave approximation for shallow flows was externally coupled to the subsurface flows to route water over the soil surface. For each soil, one experiment at the lowest slope and rainfall rate was utilized for estimation of model parameters that could not be measured independently, while all the other results were used for model corroboration. The Hydrus model indicated that a 1-D analysis would be adequate as the water front moves essentially parallel to the slope. To account for the influence of slope and soil-type on experimental results, an effective saturated conductivity was proposed. Model results were found to be in reasonable agreement with observations of surface flow, deep flow, and water contents in the soil profile with the use of the proposed effective saturated conductivity. Limitations on the applicability of the sharp-front model in this context were discussed.
Hydrological Processes, 2006
Experimental evidence of the accuracy of the model proposed by Corradini et al. (1997, Journal of... more Experimental evidence of the accuracy of the model proposed by Corradini et al. (1997, Journal of Hydrology 192: 104–124) for local infiltration–redistribution–reinfiltration in homogeneous soils is given. The model provides infiltration through the time evolution of the soil water content vertical profile, which is described by an ordinary differential equation in any stage of a given rainfall event. A nearly horizontal laboratory slope was used for the experiments performed over both a medium‐ and a coarse‐textured soil. During each experiment characterized by a complex rainfall pattern, the soil water content θ at different depths was continuously monitored using the time‐domain reflectometry method. Our results indicate that the model simulated the experimental vertical profiles of θ accurately, particularly during the infiltration and reinfiltration stages separated by a rainfall hiatus with redistribution of soil water. These results indicate the reliability of the model in computing the local effective rainfall for hydrological response. Copyright © 2005 John Wiley & Sons, Ltd.
Journal of Hydrology, 2004
This study examines the role of run-on process on field-scale infiltration and one-dimensional ov... more This study examines the role of run-on process on field-scale infiltration and one-dimensional overland flow over spatially heterogeneous hillslopes. Because of the high degree of heterogeneity exhibited by the soil parameters that govern the mechanisms of infiltration and overland flow on slopes, the analysis of hillslope hydrological processes requires a stochastic approach. The saturated hydraulic conductivity K s is considered to be the only random quantity and is represented by a lognormal random field in the horizontal directions, and the soil is assumed to be homogeneous in the vertical direction. The analysis is performed by comparing the behavior of field-scale ensemble mean and variance of infiltration and overland flow rates for cases with and without run-on. The Green-Ampt model is used to describe infiltration at the local scale as it has parameters that can be easily estimated for a wide range of soils. An extensive set of Monte-Carlo simulations for all cases is supplemented with supporting theoretical analysis for the case when run-on is negligible. Field-scale mean and variance of infiltration as functions of time are computed for different parameters of the random K s field. Results reveal that in the presence of run-on, mean field-scale infiltration increases, which in turn has a significant influence on hillslope hydrograph. Nondimensional formulation of the ensemble averaged mean and variance of infiltration and overland flow is presented with the aid of scaled variables. Two dimensionless numbers g and b expressing the characteristic time scales that govern infiltration and overland flow are developed.
Acta Geophysica, Feb 10, 2018
Journal of Hydrology, 2020
Hydrological Sciences Journal-journal Des Sciences Hydrologiques, 2004
ABSTRACT Abstract The role of accuracy in the representation of infiltration on the effectiveness... more ABSTRACT Abstract The role of accuracy in the representation of infiltration on the effectiveness ofreal-time flood forecasting models ,was investigated. A simple ,semi-distributed model of conceptual,type with adaptive estimate of hydraulic,characteristics included inthe,infiltration component ,was ,selected. Infiltration was ,described by a ,very accurate approach recently formulated for complex rainfall patterns, or alternatively through a simpler,formulation known ,as an,extension of the classical time compres- sion approximation. The results indicated that, for situations involving a significant rainfall variability in space, the inaccuracy in the representation of infiltration cannot becorrected,by the ,adaptive component ,of the rainfall–runoff model. A preliminary analysis of the role of an approximation,of saturated hydraulic conductivity to be used ineach,homogeneous ,area of the semi-distributed model ,used both in non-adaptive version and in real-time is also presented. Key words rainfall–runoff;floods; infiltration; hillslope hydrology Prévision de crue et modélisation de l’infiltration
Global warming is affecting hydroclimatic parameters determining changes in temperature and preci... more Global warming is affecting hydroclimatic parameters determining changes in temperature and precipitation patterns. In addition, human-induced activities act on the land use and land cover (LULC) features of catchments. Runoff generation can be affected by these factors in both natural and anthropogenic basins. The aim of the current study is to investigate the relationship between the runoff coefficient (Rc), computed by exploiting long-term rainfall and streamflow records, and several features that can potentially affect it, namely meteorological parameters, soil water storage (SWS), and LULC changes through the wavelet coherence analysis. The method has been applied over the Upper Tiber basin at Ponte Nuovo outlet, in central Italy. To facilitate the understanding of the current catchment conditions in terms of surface water availability, a trend analysis has been performed using the Mann-Kendall (MK) test. For the long-term period of 1927-2020, the results reveal a decreasing trend of Rc. In addition, the MK test for seasonal temperature and SWS shows increasing and decreasing trends, respectively. Based on the wavelet analysis, a significant positive correlation is observed between Rc and SWS in the annual cycle with a phase shift of less than one month, while a strong negative correlation is observed between Rc and temperature in the annual period with a phase shift of 3-6 months. The study of the relationship between Rc and LULC changes shows a weak correlation. The lower phase shift between Rc and SWS indicate that Rc is susceptible to SWS in a faster way than other components. These results allows a better understanding of the main factors influencing the Rc over the pilot area; moreover, an extension to other Mediterranean basins is foreseen as a follow-up of this work.
Journal of Hydrology, 1998
A model which couples the kinematic wave approximation for Hortonian overland flow and the concep... more A model which couples the kinematic wave approximation for Hortonian overland flow and the conceptual approach developed by Corradini et al. (1997) [J. Hydrol., 192, 104-124] for local infiltration was used to investigate the effects of random spatial variability of saturated hydraulic conductivity, Ks, on the outflow hydrograph at hillslope scale. The model incorporates a representation of infiltration of overland flow running over pervious downstream areas ("run-on" process). Single rainfall pulses and complex storms over two soils, representative of a silty loam and a sandy loam soil, were considered. Our results suggest that for realistic values of the coefficient of variation of Ks the run-on process cannot be disregarded, because it produces a significant decrease of overland flow during both the rising and the recession limb of the hydrograph. Furthermore, the role of the level of spatial correlation of Ks was found to be typically minor and the run-on process concurred to this result. The possibility of simplifying the stochastic problem by a deterministic approach based on the use of a uniform lumped value of Ks was also examined and rainfall patterns adequate for this simplification were deduced in terms of scaled storm intensity and storm duration.
Natural Hazards, Feb 10, 2021
Analyses of historical records of landslides and climate variables are useful tools to search for... more Analyses of historical records of landslides and climate variables are useful tools to search for correlations between damaging landslide events and their triggers. In this work, we investigate the temporal and geographical relationships between two long-term historical series of catalogued landslide occurrences and daily rainfall data in Umbria, a central Italian region, from 1928 to 2001. Moreover, we search for changes in the frequency and density of landslides, and in the characteristics of the associated rainfall events. Using a consolidated approach, partially modified, we find that the rainfall events that have produced rainfall-induced landslides in Umbria changed in space and time during observation period and between two considered sub-periods (1928–1975 and 1976–2001). In particular, we find that: (i) the monthly distribution of landslides associated with rainfall events is quite different than that of all landslides in the regional catalogue; (ii) the spatial and temporal distribution of REL changed from the older (most events occurred in winter) to the recent period (most events occurred in autumn); (iii) the recent most rainfall events associated with landslides are characterized by a lower cumulated rainfall and a shorter duration, sign of an increased propensity of the regional territory to produce landslides over time.
Hydrological Processes, 2006
This study first explores the role of spatial heterogeneity, in both the saturated hydraulic cond... more This study first explores the role of spatial heterogeneity, in both the saturated hydraulic conductivity Ks and rainfall intensity r, on the integrated hydrological response of a natural slope. On this basis, a mathematical model for estimating the expected areal-average infiltration is then formulated. Both Ks and r are considered as random variables with assessed probability density functions. The model
CRC Press eBooks, Nov 16, 2006
Hydrological Sciences Journal-journal Des Sciences Hydrologiques, Apr 1, 2004
The role of accuracy in the representation of infiltration on the effectiveness of real-time floo... more The role of accuracy in the representation of infiltration on the effectiveness of real-time flood forecasting models was investigated. A simple semi-distributed model of conceptual type with adaptive estimate of hydraulic characteristics included in the infiltration component was selected. Infiltration was described by a very accurate approach recently formulated for complex rainfall patterns, or alternatively through a simpler formulation known as an extension of the classical time compression approximation. The results indicated that, for situations involving a significant rainfall variability in space, the inaccuracy in the representation of infiltration cannot be corrected by the adaptive component of the rainfall-runoff model. A preliminary analysis of the role of an approximation of saturated hydraulic conductivity to be used in each homogeneous area of the semi-distributed model used both in non-adaptive version and in real-time is also presented.
Journal of Hydrologic Engineering, Apr 1, 1999
ABSTRACT This study investigated the use of similarity profiles in space for analyzing surface-ru... more ABSTRACT This study investigated the use of similarity profiles in space for analyzing surface-runoff hydrographs occurring at the outlet of small watersheds. The spatial behavior of the flow depth over each element (overland region or stream reach) was approximated by a sine function, so that the partial differential equations governing water movement were reduced to ordinary differential equations. Solutions of these reduced equations were obtained at a smaller computational cost, with analytical solutions available in some cases. These solutions then were extended to study surface water movement over small watersheds that could be represented as a sequence of cascading overland flow planes and streams. The performance of this model was studied by comparing with results from another physically based model, KINEROS, and experimental observations. It was concluded that the similarity solutions are robust and almost as accurate as numerical solutions that were obtained from physically based models, when used within their range of applicability explicitly defined in the paper. Some guidelines for spatial discretization of the watershed for appropriate use of the similarity solutions have been provided.
Journal of Hydrologic Engineering, Dec 1, 2008
ABSTRACT This paper describes laboratory experiments that provide evidence of infiltration of exc... more ABSTRACT This paper describes laboratory experiments that provide evidence of infiltration of excess runoff water from upstream areas that moves downslope over unsaturated areas (run-on process). The experiments were carried out using a tilting tank that was packed with two different natural soils to a depth of 70 cm and subjected to artificial rainfalls from a rainfall simulator. Different rainfall patterns were generated over the surface at different slope settings. Measurements of overland flow, deep flow, and soil water content, together with photographs of soil surface, were used to quantify the main features of the run-on process. The results indicate that the interaction between Hortonian overland flow and local infiltration over the permeable areas can be appropriately described by representing the flow depth per unit time as an "additional" rainfall rate. Thus, these experimental results support the representation of the run-on process that was adopted in previous numerical studies that evaluated the effects of the run-on process.
Hydrological Processes, 2002
Two models for estimating expected areal‐average infiltration rate, Ī, at the hillslope scale are... more Two models for estimating expected areal‐average infiltration rate, Ī, at the hillslope scale are presented. The first relies upon the condition of a negligible infiltration of surface water running downslope (run‐on process) into a previous heterogeneous soil. It is an adapted version of an earlier semi‐analytical model. The second incorporates the run‐on process and is based on a lumped approach that uses an effective saturated hydraulic conductivity. This latter was parameterized in terms of the main characteristics of rainfall and soil. Both the models were tested by comparison with the results carried out by Monte‐Carlo simulations over different soil types. It was found that the first model simulated Ī with maximum errors in magnitude typically less than 10%. The second model provided similar errors in the total volume of overland flow, and the rising limb of the hydrograph experienced a distortion. Lastly, satisfactory results were obtained by comparing the model without run‐on with an empirical approach particularly accurate for fine‐textured soils. Copyright © 2002 John Wiley & Sons, Ltd.
Journal of Hydrology, 2006
A semi-analytical model for the estimate of expected areal-average infiltration rate at hillslope... more A semi-analytical model for the estimate of expected areal-average infiltration rate at hillslope scale is presented. It accounts for spatial heterogeneity of the saturated hydraulic conductivity, K s , and rainfall rate, r. The K s field is characterized by a lognormal probability density function while the rainfall rate r is represented by a uniform distribution between two extreme values. The model formulation relies upon the use of cumulative infiltration as the independent variable which is then expressed as a function of an expected time for use in practical applications. The solution is applicable for those ranges of r and K s that allow for neglecting the infiltration of surface water running downslope into pervious soils (run-on process). The model was tested by comparisons with Monte Carlo simulations carried out for a variety of coefficients of variation of r and K s over a clay loam soil and a sandy loam soil. The model was found to be very reliable both with coupled spatial variability of r and K s and when only one variable is characterized by spatial heterogeneity while the other is uniform.
Journal of Hydrology, Jul 1, 2009
Summary Infiltration and deep flow on sloping surfaces were studied by combining controlled labor... more Summary Infiltration and deep flow on sloping surfaces were studied by combining controlled laboratory experiments with mathematical models. Experimental variables included soil types, rainfall intensities, and surface slopes. Preliminary analyses of the data indicated that increased slope has a positive influence on surface flow, and that this influence increases relatively with decreasing rainfall rate. However, current theories could not adequately explain the observed behavior of deep and surface flows for varying slopes. Three mathematical models of varying complexity were employed to supplement the experimental results. These models were (i) the 2-D Hydrus numerical model, (ii) numerical solution of 1-D saturated–unsaturated flow equation on sloping surfaces, and (iii) a simplified 1-D sharp-front model for sloping surfaces. For the latter two models, a surface flow component based on the kinematic wave approximation for shallow flows was externally coupled to the subsurface flows to route water over the soil surface. For each soil, one experiment at the lowest slope and rainfall rate was utilized for estimation of model parameters that could not be measured independently, while all the other results were used for model corroboration. The Hydrus model indicated that a 1-D analysis would be adequate as the water front moves essentially parallel to the slope. To account for the influence of slope and soil-type on experimental results, an effective saturated conductivity was proposed. Model results were found to be in reasonable agreement with observations of surface flow, deep flow, and water contents in the soil profile with the use of the proposed effective saturated conductivity. Limitations on the applicability of the sharp-front model in this context were discussed.
Hydrological Processes, 2006
Experimental evidence of the accuracy of the model proposed by Corradini et al. (1997, Journal of... more Experimental evidence of the accuracy of the model proposed by Corradini et al. (1997, Journal of Hydrology 192: 104–124) for local infiltration–redistribution–reinfiltration in homogeneous soils is given. The model provides infiltration through the time evolution of the soil water content vertical profile, which is described by an ordinary differential equation in any stage of a given rainfall event. A nearly horizontal laboratory slope was used for the experiments performed over both a medium‐ and a coarse‐textured soil. During each experiment characterized by a complex rainfall pattern, the soil water content θ at different depths was continuously monitored using the time‐domain reflectometry method. Our results indicate that the model simulated the experimental vertical profiles of θ accurately, particularly during the infiltration and reinfiltration stages separated by a rainfall hiatus with redistribution of soil water. These results indicate the reliability of the model in computing the local effective rainfall for hydrological response. Copyright © 2005 John Wiley & Sons, Ltd.
Journal of Hydrology, 2004
This study examines the role of run-on process on field-scale infiltration and one-dimensional ov... more This study examines the role of run-on process on field-scale infiltration and one-dimensional overland flow over spatially heterogeneous hillslopes. Because of the high degree of heterogeneity exhibited by the soil parameters that govern the mechanisms of infiltration and overland flow on slopes, the analysis of hillslope hydrological processes requires a stochastic approach. The saturated hydraulic conductivity K s is considered to be the only random quantity and is represented by a lognormal random field in the horizontal directions, and the soil is assumed to be homogeneous in the vertical direction. The analysis is performed by comparing the behavior of field-scale ensemble mean and variance of infiltration and overland flow rates for cases with and without run-on. The Green-Ampt model is used to describe infiltration at the local scale as it has parameters that can be easily estimated for a wide range of soils. An extensive set of Monte-Carlo simulations for all cases is supplemented with supporting theoretical analysis for the case when run-on is negligible. Field-scale mean and variance of infiltration as functions of time are computed for different parameters of the random K s field. Results reveal that in the presence of run-on, mean field-scale infiltration increases, which in turn has a significant influence on hillslope hydrograph. Nondimensional formulation of the ensemble averaged mean and variance of infiltration and overland flow is presented with the aid of scaled variables. Two dimensionless numbers g and b expressing the characteristic time scales that govern infiltration and overland flow are developed.