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1.
This article presents the results of a field investigation of saturated hydraulic conductivity Ksat and bulk density (ρbd) in an Atlantic blanket bog in the southwest of Ireland. Starting at a peatland stream and moving along an uphill transect toward the peatland interior, ρbd and Ksat were examined at regular intervals. Saturated horizontal hydraulic conductivity (Khsat) and vertical (Kvsat) was estimated at two depths: 10–20 and 30–40 cm below the peat surface, whereas ρbd was estimated for the full profile. We consider two separate zones, one a riparian zone extending 10 m from the stream and a second zone in the bog interior. We found that the Ksat was higher (~10–5 m s–1) in the bog interior than that in the riparian zone (~10–6 m s–1), whereas the converse applied to bulk density, with lowest density (~0.055 g cm–3) at the interior and highest (~0.11 g cm–3) at the riparian zone. In general, we found Khsat to be approximately twice the Kvsat. These results support the idea that the lower Ksat at the margins control the hydrology of blanket peatlands. It is therefore important that the spatial variation of these two key properties be accommodated in hydrological models if the correct rainfall runoff characteristics are to be correctly modelled. Stream flow analysis over 3 years at the peatland catchment outlet showed that the stream runoff was composed of 8% base flow and 92% flood flow, suggesting that this blanket peatland is a source rather than a sink for floodwaters. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

2.
A peatland complex disturbed by berm construction in the 1950s was used to examine the long‐term impact of water table (WT) manipulation on peatland hydraulic properties and moisture retention at three adjacent sites with increasing depth to WT (WET, INTermediate reference and DRY). Saturated hydraulic conductivity (Ks) was found to decrease with depth by several orders of magnitude over a depth of 1–1.5 m at all sites. The depth dependence of WT response to rainfall was similar across sites: WT response increased from 1 : 1 at the surface, to 5 : 1 at 50 cm depth. While surface specific yield (Sy) values were similar across all sites, it decreased with depth at a rate of 0.014 cm?1 in hollows and 0.007 cm?1 in hummocks. Bulk density (ρb) exhibited similar depth‐dependent trends as Sy and explains a high amount of variance (r2 > 0.69) in moisture retention across a range of pore water pressures (?15 to ?500 cm H2O). Because of higher ρb, hollow peat had greater moisture retention, where site effects were minimal. However, the estimated residual water content for surface Sphagnum samples, while on average lower in hummocks (0.082 m3 m?3) versus hollows (0.087 m3 m?3), increased from WET (0.058 m3 m?3) to INT (0.088 m3 m?3) to DRY (0.108 m3 m?3) which has important implications for moisture stress under conditions of persistent WT drawdown. Given the potential importance of microtopographic succession for altering peatland hydraulic structure, our findings point to the need for a better understanding of what controls the relative height and proportional coverage of hummocks in relation to long‐term disturbance‐response dynamics. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

3.
Abstract

Piezometers and wells installed for water quality monitoring are frequently used to assess the saturated hydraulic conductivity (K) in the surrounding formation. A series of recovery tests was conducted to evaluate how purging, required to obtain representative water quality samples, affected measured values of hydraulic conductivity in 15 newly installed and undeveloped piezometers placed to between 2 and 15 m depth (in oxidized and unoxidized material) in a loamy glacial till (K range from 10?6 to 10?9 m s?1). Piezometers were purged between 9 and 11 times for sampling over a period of five months. The effect of the purgings on piezometer development was evaluated by changes in slope of the water level recovery curves which were used to calculate hydraulic conductivity. The first five purgings following piezometer installation increased K in the 15 piezometers by an average of 34%. The average increase in a value of K after 10 purgings was 44%. Values measured for hydraulic conductivity in a 75 mm diameter auger hole appeared stable after four purgings but piezometers installed in larger diameter boreholes (100 mm to 280 mm) snowed increases in K with up to 10 purgings. The hydraulic conductivity determined for piezometers installed at a 30° angle to the vertical showed greater variability than was observed in the adjacent vertically installed piezometers at the same depth.  相似文献   

4.
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5.
Post‐wildfire runoff was investigated by combining field measurements and modelling of infiltration into fire‐affected soils to predict time‐to‐start of runoff and peak runoff rate at the plot scale (1 m2). Time series of soil‐water content, rainfall and runoff were measured on a hillslope burned by the 2010 Fourmile Canyon Fire west of Boulder, Colorado during cyclonic and convective rainstorms in the spring and summer of 2011. Some of the field measurements and measured soil physical properties were used to calibrate a one‐dimensional post‐wildfire numerical model, which was then used as a ‘virtual instrument’ to provide estimates of the saturated hydraulic conductivity and high‐resolution (1 mm) estimates of the soil‐water profile and water fluxes within the unsaturated zone. Field and model estimates of the wetting‐front depth indicated that post‐wildfire infiltration was on average confined to shallow depths less than 30 mm. Model estimates of the effective saturated hydraulic conductivity, Ks, near the soil surface ranged from 0.1 to 5.2 mm h?1. Because of the relatively small values of Ks, the time‐to‐start of runoff (measured from the start of rainfall), tp, was found to depend only on the initial soil‐water saturation deficit (predicted by the model) and a measured characteristic of the rainfall profile (referred to as the average rainfall acceleration, equal to the initial rate of change in rainfall intensity). An analytical model was developed from the combined results and explained 92–97% of the variance of tp, and the numerical infiltration model explained 74–91% of the variance of the peak runoff rates. These results are from one burned site, but they strongly suggest that tp in fire‐affected soils (which often have low values of Ks) is probably controlled more by the storm profile and the initial soil‐water saturation deficit than by soil hydraulic properties. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.  相似文献   

6.
The frequency and intensity of drought is projected to increase within the boreal region under future climatic conditions. Peatlands are widely considered to regulate water loss under drought conditions, increasing surface resistance (rs) and reducing evaporative losses. This maintains peat moisture content, increasing the resilience of these globally important carbon stores. However, the magnitude and form of this important negative feedback response remains uncertain. To address this, we monitored the response of rs to drought within four peat cores under controlled meteorological conditions. When the water‐table was dropped to a depth of 0.30 m and the humidity reduced to ≤40%, a step shift in rs from ~50 s m‐1 up to 1000 s m‐1 was observed within burned and unburned peat, which virtually shuts down evaporation, limiting water loss. We show that measured near‐surface tension cannot be used to directly calculate this transition in peat surface resistance. However, empirical relationships that account for strong vertical variations in tension through the near‐surface and/or disequilibrium between pore air and near‐surface pore water pressure provide the potential to incorporate this negative feedback response into peatland ecohydrological models. Further observations are necessary to examine this response under dynamic atmospheric conditions. We suggest that the link between surface temperature and evaporation provides potential to further examine this feedback in either burned peatlands or peatlands with a low vascular vegetation cover. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

7.
Saturated hydraulic conductivity (Ks) affects the soil hydrological process and is influenced by many factors that exhibit strong spatial variations. To accurately measure Ks and its scale, spatial variability and relationship with collapsing gullies, we analysed four double-ring infiltrometer diameters in three soil layers during in situ experiments designed to measure Ks in two typical collapsing gullies (three slope sites) in Tongcheng County of China. The results showed that Ks increased with increasing inner ring diameter, but no significant difference existed between inner diameters of 30 and 40 cm. The Ks in red soil layers was higher than that in sandy soil layers, the transition layers had the lowest values. Ks also varied with slope position, gradually decreasing with distance from the gully head. The suggestion is that the spatial variation in Ks is affected not only by the intrinsic soil properties but also by the interaction with the collapsing gully.  相似文献   

8.
The distribution of soil hydraulic and physical properties strongly influences runoff processes in landscapes. Although much work has been done to quantify and predict the properties of hillslope soils, far less is known about the distribution of soil properties in valley floors. A technique that links the estimation and distribution of soil hydraulic properties in valleys, with easily identified geomorphic features, was developed along a 2 km length of a valley at Brooks Creek in New South Wales, Australia. Soil physical and hydraulic property data were collected across a set of floodplain and fan features within the valley and analysed statistically to determine if soil properties varied significantly between geomorphic features and stratigraphic layers. The results show that the depth‐averaged saturated hydraulic conductivity, Ks, of the soil varies significantly with landform: fan units have Kg values that are twice that of floodplains and colluvial toeslope deposits have Ks values four times higher than floodplains. Given the notorious variability of Ks values in space, the strong statistical separation of soil properties by landform, backed up by strong separation of soil particle size by landform, suggests a way forward in understanding the distribution of soil properties in valleys and their influence on catchment hydrology. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

9.
Peat specific yield (SY) is an important parameter involved in many peatland hydrological functions such as flood attenuation, baseflow contribution to rivers, and maintaining groundwater levels in surficial aquifers. However, general knowledge on peatland water storage capacity is still very limited, due in part to the technical difficulties related to in situ measurements. The objectives of this study were to quantify vertical SY variations of water tables in peatlands using the water table fluctuation (WTF) method and to better understand the factors controlling peatland water storage capacity. The method was tested in five ombrotrophic peatlands located in the St. Lawrence Lowlands (southern Québec, Canada). In each peatland, water table wells were installed at three locations (up‐gradient, mid‐gradient, and down‐gradient). Near each well, a 1‐m long peat core (8 cm × 8 cm) was sampled, and subsamples were used to determine SY with standard gravitational drainage method. A larger peat sample (25 cm × 60 cm × 40 cm) was also collected in one peatland to estimate SY using a laboratory drainage method. In all sites, the mean water table depth ranged from 9 to 49 cm below the peat surface, with annual fluctuations varying between 15 and 29 cm for all locations. The WTF method produced similar results to the gravitational drainage experiments, with values ranging between 0.13 and 0.99 for the WTF method and between 0.01 and 0.95 for the gravitational drainage experiments. SY was found to rapidly decrease with depth within 20 cm, independently of the within‐site location and the mean annual water table depth. Dominant factors explaining SY variations were identified using analysis of variance. The most important factor was peatland site, followed by peat depth and seasonality. Variations in storage capacity considering site and seasonality followed regional effective growing degree days and evapotranspiration patterns. This work provides new data on spatial variations of peatland water storage capacity using an easily implemented method that requires only water table measurements and precipitation data.  相似文献   

10.
Simulation of soil moisture content requires effective soil hydraulic parameters that are valid at the modelling scale. This study investigates how these parameters can be estimated by inverse modelling using soil moisture measurements at 25 locations at three different depths (at the surface, at 30 and 60 cm depth) on an 80 by 20 m hillslope. The study presents two global sensitivity analyses to investigate the sensitivity in simulated soil moisture content of the different hydraulic parameters used in a one‐dimensional unsaturated zone model based on Richards' equation. For estimation of the effective parameters the shuffled complex evolution algorithm is applied. These estimated parameters are compared to their measured laboratory and in situ equivalents. Soil hydraulic functions were estimated in the laboratory on 100 cm3 undisturbed soil cores collected at 115 locations situated in two horizons in three profile pits along the hillslope. Furthermore, in situ field saturated hydraulic conductivity was estimated at 120 locations using single‐ring pressure infiltrometer measurements. The sensitivity analysis of 13 soil physical parameters (saturated hydraulic conductivity (Ks), saturated moisture content (θs), residual moisture content (θr), inverse of the air‐entry value (α), van Genuchten shape parameter (n), Averjanov shape parameter (N) for both horizons, and depth (d) from surface to B horizon) in a two‐layer single column model showed that the parameter N is the least sensitive parameter. Ks of both horizons, θs of the A horizon and d were found to be the most sensitive parameters. Distributions over all locations of the effective parameters and the distributions of the estimated soil physical parameters from the undisturbed soil samples and the single‐ring pressure infiltrometer estimates were found significantly different at a 5% level for all parameters except for α of the A horizon and Ks and θs of the B horizon. Different reasons are discussed to explain these large differences. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

11.
Changes in Entrapped Gas Content and Hydraulic Conductivity with Pressure   总被引：1，自引：0，他引：1  
Water table fluctuations continuously introduce entrapped air bubbles into the otherwise saturated capillary fringe and groundwater zone, which reduces the effective (quasi‐saturated) hydraulic conductivity, Kquasi, thus impacting groundwater flow, aquifer recharge and solute and contaminant transport. These entrapped gases will be susceptible to compression or expansion with changes in water pressure, as would be expected with water table (and barometric pressure) fluctuations. Here we undertake laboratory experiments using sand‐packed columns to quantify the effect of water table changes of up to 250 cm on the entrapped gas content and the quasi‐saturated hydraulic conductivity, and discuss our ability to account for these mechanisms in ground water models. Initial entrapped air contents ranged between 0.080 and 0.158, with a corresponding Kquasi ranging between 2 and 6 times lower compared to the Ks value. The application of 250 cm of water pressure caused an 18% to 26% reduction in the entrapped air content, resulting in an increase in Kquasi by 1.16 to 1.57 times compared to its initial (0 cm water pressure) value. The change in entrapped air content measured at pressure step intervals of 50 cm, was essentially linear, and could be modeled according to the ideal gas law. Meanwhile, the changes in Kquasi with compression–expansion of the bubbles because of pressure changes could be adequately captured with several current hydraulic conductivity models.  相似文献   

12.
Field‐saturated soil hydraulic conductivity, Kfs, is highly variable. Therefore, interpreting and simulating hydrological processes, such as rainfall excess generation, need a large number of Kfs data even at the plot scale. Simple and reasonably rapid experiments should be carried out in the field. In this investigation, a simple infiltration experiment with a ring inserted shortly into the soil and the estimation of the so‐called α* parameter allowed to obtain an approximate measurement of Kfs. The theoretical approach was tested with reference to 149 sampling points established on Burundian soils. The estimated Kfs with the value of first approximation of α* for most agricultural field soils (α* = 0.012 mm?1) differed by a practically negligible maximum factor of two from the saturated conductivity obtained by the complete Beerkan Estimation of Soil Transfer parameters (BEST) procedure for soil hydraulic characterization. The measured infiltration curve contained the necessary information to obtain a site‐specific prediction of α*. The empirically derived α* relationship gave similar results for Kfs (mean = 0.085 mm s?1; coefficient of variation (CV) = 71%) to those obtained with BEST (mean = 0.086 mm s?1; CV = 67%), and it was also successfully tested with reference to a few Sicilian sampling points, since it yielded a mean and a CV of Kfs (0.0094 mm s?1 and 102%, respectively) close to the values obtained with BEST (mean = 0.0092 mm s?1; CV = 113%). The developed method appears attractive due to the extreme simplicity of the experiment. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

13.
Our understanding of hydraulic properties of peat soils is limited compared with that of mineral substrates. In this study, we aimed to deduce possible alterations of hydraulic properties of peat soils following degradation resulting from peat drainage and aeration. A data set of peat hydraulic properties (188 soil water retention curves [SWRCs], 71 unsaturated hydraulic conductivity curves [UHCs], and 256 saturated hydraulic conductivity [Ks] values) was assembled from the literature; the obtained data originated from peat samples with an organic matter (OM) content ranging from 23 to 97 wt% (weight percent; and according variation in bulk density) representing various degrees of peat degradation. The Mualem‐van Genuchten model was employed to describe the SWRCs and UHCs. The results show that the hydraulic parameters of peat soils vary over a wide range confirming the pronounced diversity of peat. Peat decomposition significantly modifies all hydraulic parameters. A bulk density of approximately 0.2 g cm?3 was identified as a critical threshold point; above and below this value, macroporosity and hydraulic parameters follow different functions with bulk density. Pedotransfer functions based on physical peat properties (e.g., bulk density and soil depth) separately computed for bog and fen peat have significantly lower mean square errors than functions obtained from the complete data set, which indicates that not only the status of peat decomposition but also the peat‐forming plants have a large effect on hydraulic properties. The SWRCs of samples with a bulk density of less than 0.2 g cm?3 could be grouped into two to five classes for each peat type (botanical composition). The remaining SWRCs originating from samples with a bulk density of larger than 0.2 g cm?3 could be classified into one group. The Mualem‐van Genuchten parameter values of α can be used to estimate Ks if no Ks data are available. In conclusion, the derived pedotransfer functions provide a solid instrument to derive hydraulic parameter values from easily measurable quantities; however, additional research is required to reduce uncertainty.  相似文献   

14.
Perennial pools are common natural features of peatlands, and their hydrological functioning and turnover may be important for carbon fluxes, aquatic ecology, and downstream water quality. Peatland restoration methods such as ditch blocking result in many new pools. However, little is known about the hydrological function of either pool type. We monitored six natural and six artificial pools on a Scottish blanket peatland. Pool water levels were more variable in all seasons in artificial pools having greater water level increases and faster recession responses to storms than natural pools. Pools overflowed by a median of 9 and 54 times pool volume per year for natural and artificial pools, respectively, but this varied widely because some large pools had small upslope catchments and vice versa. Mean peat water‐table depths were similar between natural and artificial pool sites but much more variable over time at the artificial pool site, possibly due to a lower bulk specific yield across this site. Pool levels and pool‐level fluctuations were not the same as those of local water tables in the adjacent peat. Pool‐level time series were much smoother, with more damped rainfall or recession responses than those for peat water tables. There were strong hydraulic gradients between the peat and pools, with absolute water tables often being 20–30 cm higher or lower than water levels in pools only 1–4 m away. However, as peat hydraulic conductivity was very low (median of 1.5 × 10?5 and 1.4 × 10?6 cm s?1 at 30 and 50 cm depths at the natural pool site), there was little deep subsurface flow interaction. We conclude that (a) for peat restoration projects, a larger total pool surface area is likely to result in smaller flood peaks downstream, at least during summer months, because peatland bulk specific yield will be greater; and (b) surface and near‐surface connectivity during storm events and topographic context, rather than pool size alone, must be taken into account in future peatland pool and stream chemistry studies.  相似文献   

15.
Limited information exists on one of the mechanisms governing sediment input to streams: streambank erosion by ground water seepage. The objective of this research was to demonstrate the importance of streambank composition and stratigraphy in controlling seepage flow and to quantify correlation of seepage flow/erosion with precipitation, stream stage and soil pore water pressure. The streambank site was located in Northern Mississippi in the Goodwin Creek watershed. Soil samples from layers on the streambank face suggested less than an order of magnitude difference in vertical hydraulic conductivity (Ks) with depth, but differences between lateral Ks of a concretion layer and the vertical Ks of the underlying layers contributed to the propensity for lateral flow. Goodwin Creek seeps were not similar to other seeps reported in the literature, in that eroded sediment originated from layers underneath the primary seepage layer. Subsurface flow and sediment load, quantified using 50 cm wide collection pans, were dependent on the type of seep: intermittent low‐flow (LF) seeps (flow rates typically less than 0·05 L min?1), persistent high‐flow (HF) seeps (average flow rate of 0·39 L min?1) and buried seeps, which eroded unconsolidated bank material from previous bank failures. The timing of LF seeps correlated to river stage and precipitation. The HF seeps at Goodwin Creek began after rainfall events resulted in the adjacent streambank reaching near saturation (i.e. soil pore water pressures greater than ?5 kPa). Seep discharge from HF seeps reached a maximum of 1·0 L min?1 and sediment concentrations commonly approached 100 g L?1. Buried seeps were intermittent but exhibited the most significant erosion rates (738 g min?1) and sediment concentrations (989 g L?1). In cases where perched water table conditions exist and persistent HF seeps occur, seepage erosion and bank collapse of streambank sediment may be significant. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

16.
A first-order moment analysis method is introduced to evaluate the pore-water pressure variability within a hillslope due to spatial variability in saturated hydraulic conductivity (Ks) during rainfall. The influences of the variance of the natural logarithm of Ks(ln Ks), spatial structure anisotropy of ln Ks, and normalized vertical infiltration flux (q) on the evaluations of the pore-water pressure uncertainty are investigated. Results indicate different responses of pressure head variability in the unsaturated region and the saturated region. In the unsaturated region, a larger variance of ln Ks, a higher spatial structure anisotropy, and a smaller q lead to a larger variability in pressure head, while in the saturated region, the variability in pressure head increases with the increase of variance of ln Ks, the decrease of spatial structure anisotropy, or the increase of q. These variables have great impacts on the range of fluctuation of the phreatic surface within the hillslope. The influences of these three variables on the variance of pressure head within the saturated region are greater than those within the unsaturated region, and the variance of ln Ks has the greatest impact. These results yield useful insight into the effects of heterogeneity on pressure head and uncertainty associated with predicted flow field.  相似文献   

17.
We investigated the changes of saturated hydraulic conductivity, Ksat , with depth of latosols developed on Precambrian basement rocks under primary rainforest, pasture and teak. In all cases, Ksat decreased with depth, with most of the decrease occurring between the surface and a depth of 30 cm. In conjunction with prevailing rainfall intensities and frequencies, this anisotropy supports a pronounced lateral component of hillslope flow paths, and also of overland flow under pasture. Our results are at variance with data from other latosols where Ksat tends to increase with depth, and hence suggest that considerable restraint is needed in generalization and extrapolation until results from a co‐ordinated effort at hydrology‐oriented data collection become available. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

18.
It has long been understood that streambed hydraulic conductivity plays an important role in surface-subsurface solute exchange. Using a portable falling head permeameter in situ, we estimated the horizontal hydraulic conductivity, K, of the near-surface streambed sediments at a total of 85 locations encompassing two depth intervals: 7.5–10 and 10–12.5 cm. The measurements were conducted in an 80 m reach of Indian Creek, a small urban stream in Philadelphia, PA, USA. We found that the ln K data within each sediment layer were Gaussian, but the combined data set was not. The results indicated that while the mean hydraulic conductivity decreased with depth, horizontal heterogeneity (e.g. the variance) increased with depth. This strong contrast between layers suggests that they should be treated as separated entities in modeling studies. Variogram analyses across the stream suggested symmetry with respect to the thalweg in the upper layer and fractality in the lower layer. The variograms along the streams suggested that the K data are random.  相似文献   

19.
In north‐central Oklahoma eastern redcedar (Juniperus virginiana), encroachment into grassland is widespread and is suspected of reducing streamflow, but the effects of this encroachment on soil hydraulic properties are unknown. This knowledge gap creates uncertainty in understanding the hydrologic effects of eastern redcedar encroachment and obstructs fact‐based management of encroached systems. The objective of this study was to quantify the effects of eastern redcedar encroachment into tallgrass prairie on soil hydraulic properties. Leaf litter depth, soil organic matter, soil water repellency, soil water content, sorptivity, and unsaturated hydraulic conductivity were measured near Stillwater, OK, along 12 radial transects from eastern redcedar trunks to the center of the grassy intercanopy space. Eastern redcedar encroachment in the second half of the 20th century caused the accumulation of 3 cm of hydrophobic leaf litter near the trunks of eastern redcedar trees. This leaf litter was associated with increased soil organic matter in the upper 6 cm of soil under eastern redcedar trees (5.96% by mass) relative to the grass‐dominated intercanopy area (3.99% by mass). Water repellency was more prevalent under eastern redcedar than under grass, and sorptivity under eastern redcedar was 0.10 mm s?1/2, one seventh the sorptivity under adjacent prairie grasses (0.68 mm s?1/2). Median unsaturated hydraulic conductivity under grass was 2.52 cm h?1, four times greater than under eastern redcedar canopies (0.57 cm h?1). Lower sorptivity and unsaturated hydraulic conductivity would tend to decrease infiltration and increase runoff, but other factors such as rainfall interception by the eastern redcedar canopy and litter layer, and preferential flow induced by hydrophobicity must be examined before the effects of encroachment on streamflow can be predicted. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
Abstract

Soil water content (θ) and saturated hydraulic conductivity (Ks) vary in space. The objective of this study was to examine the effects of initial soil water content (θi) and Ks variability on runoff simulations using the LImburg Soil Erosion Model (LISEM) in a small watershed in the Chinese Loess Plateau, based on model parameters derived from intensive measurements. The results showed that the total discharge (TD) and peak discharge (PD) were underestimated when the variability of θi and Ks was partially considered or completely ignored compared with those when the variability was fully considered. Time to peak (TP) was less affected by the spatial variability compared to TD and PD. Except for TP in some cases, significant differences were found in all hydrological variables (TD, PD and TP) between the cases in which spatial variability of θi or Ks was fully considered and those in which spatial variability was partially considered or completely ignored. Furthermore, runoff simulations were affected more strongly by Ks variability than by θi variability. The degree of spatial variability influences on runoff simulations was related to the rainfall pattern and θi. Greater rainfall depth and instantaneous rainfall intensity corresponded to a smaller influence of the spatial variability. Stronger effects of the θi variability on runoff simulation were found in wetter soils, while stronger effects of the Ks variability were found in drier soils. For accurate runoff simulation, the θi variability can be completely ignored in cases of a 1-h duration storm with a return period greater than 10 years, while Ks variability should be fully considered even in the case of a 1-h duration storm with a return period of 20 years.
Editor D. Koutsoyiannis; Associate editor A. Fiori  相似文献   

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