Evaluation of rapid approaches for determining the soil water retention function and saturated hydraulic conductivity in a hydrologically complex soil

Weninger

Journal of Hydrology and Hydromechanics

et al. 2018

Abstract:Global climate change is projected to continue and result in prolonged and more intense droughts, which can increase soil water repellency (SWR). To be able to estimate the consequences of SWR on vadose zone hydrology, it is important to determine soil hydraulic properties (SHP). Sequential modeling using HYDRUS (2D/3D) was performed on an experimental field site with artificially imposed drought scenarios (moderately M and severely S stressed) and a control plot. First, inverse modeling was performed for SHP estimation based on water and ethanol infiltration experimental data, followed by model validation on one selected irrigation event. Finally, hillslope modeling was performed to assess water balance for 2014. Results suggest that prolonged dry periods can increase soil water repellency. Inverse modeling was successfully performed for infiltrating liquids, water and ethanol, with R 2 and model efficiency (E) values both > 0.9. SHP derived from the ethanol measurements showed large differences in van Genuchten-Mualem (VGM) parameters for the M and S plots compared to water infiltration experiments. SWR resulted in large saturated hydraulic conductivity (K s ) decrease on the M and S scenarios. After validation of SHP on water content measurements during a selected irrigation event, one year simulations (2014) showed that water repellency increases surface runoff in non-structured soils at hillslopes.

Section: Introductionmentioning

confidence: 99%

Inverse estimation of soil hydraulic properties and water repellency following artificially induced drought stress

Weninger

Journal of Hydrology and Hydromechanics

et al. 2018

“…Considering all three soil layers, the drainable structural water content (θ str‐BE ) at the farmland locations was greater on 9 March (in the range of 0.099–0.163 m 3 m −3 ) and 7 May (in the range of 0.079–0.216 m 3 m −3 ) than the other sampling times (in the range of 0.044–0.089 m 3 m −3 ), while for the forestland, higher values of θ str‐BE were seen only on the driest 9 March (in the range of 0.067–0.134 m 3 m −3 ). Previous studies have shown that preferential flow via structural pores can be enhanced by increased water repellency (i.e., decreased soil wettability) following drying (Hardie et al, 2013). A plausible explanation for the higher θ str‐BE on 9 March for both the farmland and the forestland is that more water was retained by the increased volume of structural pores due to shrinkage during drying.…”

Section: Resultsmentioning

confidence: 99%

Within‐Year Changes in Hydraulic Properties of a Shallow Entisol in Farmland and Forestland

Wang

Tang

Zhang

et al. 2015

Vadose Zone Journal

For regions with shallow soils underlain by fractured parent rocks, it is important to understand the characteristics of soil water retention and hydraulic conductivity. This knowledge could support the development of strategies to manage water for crops. A farmland and a forestland with thin Entisols, located in hilly central Sichuan on the Yangtze River's upper reaches, were chosen as experimental ields. A variety of parameters related to hydraulically effective macroporosity (pore radius >125 mm), the single-porosity van Genuchten model, and the dual-porosity bi-exponential (BE) model for water retention characteristics were determined. Tension iniltration data showed that soil macropores were the main pores (accounting for 87.9-99.7%) contributing to fast drainage at all tested soil depths under both land uses in the rainy summer, in spite of their very low percentage of the total porosity (0.61-3.06%). The available soil water content, determined as the drainable soil textural porosity using the bi-exponential model (q txt-BE ), was found to be very low (0.032-0.091 m 3 m −3 ) and negatively (P < 0.05) related to the initial soil water content at the time of sampling, resulting in high vulnerability of the crops grown on the farmland to drought. Plowing operations and periodical drying appeared to be the two main factors controlling the within-year change in soil hydraulic properties. For agricultural soils showing a bimodal pore size distribution, the soil's capacity to hold crop-available water in textural pores, which may vary with the time of year, rather than the total soil water content should be analyzed to inform decisions on irrigation operations including required amounts.

“…Measured soil physical attributes included particle size (Indorante et al, 1990), linear shrinkage (McGarry, 2002), Atterberg limits (McBride, 2008), and dispersion class (Emerson, 1991), reported in Hardie (2011). The soil water characteristic was determined by desorption (Cresswell, 2002), evaporative flux (Wendroth and Wypler, 2008), and inverse solution of tension infiltration data (Šimůnek et al, 1998), reported in Hardie et al (2013b). Saturated hydraulic conductivity was determined by the constant‐head approach on intact cores (McKenzie et al, 2002b) and extrapolation and inverse solution of tension infiltration data (Šimůnek et al, 1998), reported in Hardie et al (2012d, 2013b).…”

Section: Methodsmentioning

confidence: 99%

“…The soil water characteristic was determined by desorption (Cresswell, 2002), evaporative flux (Wendroth and Wypler, 2008), and inverse solution of tension infiltration data (Šimůnek et al, 1998), reported in Hardie et al (2013b). Saturated hydraulic conductivity was determined by the constant‐head approach on intact cores (McKenzie et al, 2002b) and extrapolation and inverse solution of tension infiltration data (Šimůnek et al, 1998), reported in Hardie et al (2012d, 2013b). Volumetric soil shrinkage was determined by the balloon approach (Cornelis et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

“…Australian Soil Classiication (Isbell, 2002) Great Soil Group (Stephens, 1953) Factual key (Northcote, 1979) Soil taxonomy (Soil Survey Staf, 2006) (2013b). Saturated hydraulic conductivity was determined by the constant-head approach on intact cores (McKenzie et al, 2002b) and extrapolation and inverse solution of tension iniltration data (Šimůnek et al, 1998), reported in Hardie et al (2012dHardie et al ( , 2013b. Volumetric soil shrinkage was determined by the balloon approach (Cornelis et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Hydropedology and Preferential Flow in the Tasmanian Texture‐Contrast Soils

Hardie

Doyle

Cotching

et al. 2013

Vadose Zone Journal

Self Cite

The two‐way interaction between soil morphology and the processes governing soil water movement were investigated for a range of texture‐contrast soil profiles. The texture‐contrast soils consisted of a seasonally water‐repellent sandy loam A1 horizon over a bleached silica‐cemented A2e horizon and a mottled vertic clay subsoil. Differences in soil morphology and structure among sites had little influence on the proportion of soil that participated in infiltration or the maximum depth of infiltration; however, differences in subsoil structure influenced the processes by which water infiltrated and was stored within the B2 horizons. The occurrence of preferential flow was largely controlled by the effects of antecedent soil moisture content on water repellence in the A1 horizon, silica bridging in the A2e horizon, and clay shrinkage in the B2 horizons. Under dry soil conditions, infiltration resulted from up to five different forms of preferential flow. When soils were near field capacity, most forms of preferential flow ceased; however, wetting front instability and lateral flow developed in the A1 horizon. Preferential flows are not thought to have contributed to the pedogenesis of the texture‐contrast soils. Development of the contrasting soil texture horizons, sand infills, and bleached A2e horizons developed before and independently of the observed preferential flow processes in which reworked aeolian sands buried previously developed clay columns.