scholarly journals Large-scale lateral saturated soil hydraulic conductivity as metric for the connectivity of the subsurface flow paths at hillslope scale

2021 ◽  
Author(s):  
Mario Pirastru ◽  
Massimo Iovino ◽  
Hassan Awada ◽  
Roberto Marrosu ◽  
Simone Di Prima ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Spatial Scale ◽  
Water Table ◽  
Subsurface Flow ◽  
Lateral Flow ◽  
Saturated Soil ◽  
Flow Paths ◽  
Soil Hydraulic Conductivity ◽  
Hillslope Scale

Lateral saturated soil hydraulic conductivity, Ks,l, is the soil property governing subsurface water transfer in hillslopes, and the key parameter in many numerical models simulating hydrological processes both at the hillslope and catchment scales. Likewise, the hydrological connectivity of lateral flow paths plays a significant role in determining the intensity of the subsurface flow at various spatial scales. The objective of the study is to investigate the relationship between Ks,l and hydraulic connectivity at the hillslope spatial scale. Ks,l was determined by the subsurface flow rates intercepted by drains, and by water table depths observed in a well network. Hydraulic connectivity of the lateral flow paths was evaluated by the synchronicity among piezometric peaks, and between the latter and the peaks of drained flow. Soil moisture and precipitation data were used to investigate the influence of the transient hydrological soil condition on connectivity and Ks,l. It was found that the higher was the synchronicity of the water table response between wells, the lower was the time lag between the peaks of water levels and those of the drained subsurface flow. Moreover, the most synchronic water table rises determined the highest drainage rates. The relationships between Ks,l and water table depths were highly non-linear, with a sharp increase of the values for water table levels close to the soil surface. Estimated Ks,l values for the full saturated soil were in the order of thousands of mm h-1, suggesting the activation of macropores in the root zone. The Ks,l values determined at the peak of the drainage events were correlated with the indicators of synchronicity. The sum of the antecedent soil moisture and of the precipitation was correlated with the indicators of connectivity and with Ks,l. We suggest that, for simulating realistic processes at the hillslope scale, the hydraulic connectivity could be implicitly considered in hydrological modelling through an evaluation of Ks,l at the same spatial scale.

Characterizing Hydrological Fluxes of Lesser Himalayan hillslopes

2020 ◽  
Author(s):  
Aliva Nanda ◽  
Sumit Sen
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Soil Temperature ◽  
Soil Properties ◽  
Negative Correlation ◽  
Soil Hydraulic Conductivity ◽  
Hydrological Fluxes ◽  
Soil Hydraulic ◽  
Hillslope Scale ◽  
Hillslope Processes

<p>Hillslope-scale studies play a vital role in understanding the spatial and temporal dynamics of hydrological fluxes of an ungauged watershed. The linkage between static (i.e. topography, soil properties and landuse) and dynamic (i.e. runoff, soil moisture and temperature) characteristics of a hillslope provides a new insight towards hillslope processes. Thus, two Lesser Himalayan hillslopes of Aglar watershed have been selected in two different landuses (grass-covered and agro-forested) and aspects (south and north). In this study, we analyzed the different hydrological fluxes i.e. rainfall, runoff, soil moisture and soil temperature along with the soil properties to get a holistic understanding of hillslope processes. We used the soil moisture dynamics and soil hydraulic conductivity as the major components to derive the hillslope hydrological connectivity. It was observed that the grassed (GA) hillslope generates less runoff than the agro-forested (AgF) hillslope as the upslope runoff of GA hillslope re-infiltrated in the middle portion due to higher soil hydraulic conductivity and surface resistance. Further, this explains that the runoff contributing areas are located at the lower and upper portions of hillslopes due to the presence of low soil hydraulic conductivity zones.  As both the hillslopes are dominated with Hortonian overland flow, the negative correlation was found between topographic indices (TWI) and soil moisture and positive correlation was noticed between soil hydraulic conductivity. Higher runoff (less infiltration) from AgF hillslope results in a higher negative correlation between TWI and soil moisture in comparison to GA hillslope. This results in a higher rate of change in soil temperature of GA hillslope than the AgF hillslope. After analyzing 40 rainfall events, it was concluded that a temperature drop of more than 2<sup>o</sup>C was recorded when the average rainfall intensity and event duration exceeds 7.5mm/hr and 7.5hr, respectively. The understanding of covariance of these hydrological fluxes will be used in the future to develop a hillslope-scale conceptual model.</p>

scholarly journals Estimating the macroscopic capillary length from Beerkan infiltration experiments and its impact on saturated soil hydraulic conductivity predictions

2020 ◽  
Vol 589 ◽  
pp. 125159 ◽  
Author(s):  
Simone Di Prima ◽  
Ryan D. Stewart ◽  
Mirko Castellini ◽  
Vincenzo Bagarello ◽  
Majdi R. Abou Najm ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Saturated Soil ◽  
Capillary Length ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

Identifying Covariates to Assess the Spatial Variability of Saturated Soil Hydraulic Conductivity Using Robust Cokriging at the Watershed Scale

2020 ◽  
Vol 20 (3) ◽  
pp. 1491-1502 ◽  
Author(s):  
Mauricio Fornalski Soares ◽  
Luana Nunes Centeno ◽  
Luís Carlos Timm ◽  
Carlos Rogério Mello ◽  
Douglas Rodrigo Kaiser ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Saturated Soil ◽  
Watershed Scale ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

Identifying regionalized co-variate driving factors to assess spatial distributions of saturated soil hydraulic conductivity using multivariate and state-space analyses

CATENA ◽  
2020 ◽  
Vol 191 ◽  
pp. 104583
Author(s):  
Luana Nunes Centeno ◽  
Luís Carlos Timm ◽  
Klaus Reichardt ◽  
Samuel Beskow ◽  
Tamara Leitzke Caldeira ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
State Space ◽  
Driving Factors ◽  
Saturated Soil ◽  
Spatial Distributions ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

Effect of Soil Sample Size on Saturated Soil Hydraulic Conductivity

2017 ◽  
Vol 48 (8) ◽  
pp. 908-919 ◽  
Author(s):  
Roya Jafari ◽  
Vahedberdi Sheikh ◽  
Mohsen Hossein-Alizadeh ◽  
Hasan Rezaii-Moghadam
Keyword(s):  
Hydraulic Conductivity ◽  
Sample Size ◽  
Soil Sample ◽  
Saturated Soil ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

scholarly journals On the shape of forward transit time distributions in low-order catchments

2019 ◽  
Author(s):  
Ingo Heidbüchel ◽  
Jie Yang ◽  
Andreas Musolff ◽  
Peter Troch ◽  
Ty Ferré ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Transit Time ◽  
Precipitation Amount ◽  
Precipitation Event ◽  
Dimensionless Number ◽  
Flow Paths ◽  
Antecedent Soil Moisture ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
Low Order

Abstract. Transit time distributions (TTDs) integrate information on timing, amount, storage, mixing and flow paths of water and thus characterize hydrologic and hydrochemical catchment response unlike any other descriptor. Here, we simulate the shape of TTDs in an idealized low-order catchment investigating whether it changes systematically with certain catchment and climate properties. To this end, we used a physically-based, spatially-explicit 3-D model, injected tracer with a precipitation event and recorded the resulting TTDs at the outlet of a small (~ 6000 m2) catchment for different scenarios. We found that the TTDs can be subdivided into four parts: 1) early part – controlled by soil hydraulic conductivity and antecedent soil moisture content, 2) middle part – transition zone with no clear pattern or control, 3) later part – influenced by soil hydraulic conductivity and subsequent precipitation amount and 4) very late tail of the breakthrough curve – governed by bedrock hydraulic conductivity. The modeled TTD shapes can be predicted using a dimensionless number: higher initial peaks are observed if the inflow of water to a catchment is not equal to its capacity to discharge water via subsurface flow paths, lower initial peaks are connected to increasing available storage. In most cases the modeled TTDs were humped with non-zero initial values and varying weights of the tails. Therefore, none of the best-fit theoretical probability functions could exactly describe the entire TTD shape. Still, we found that generally the Gamma and the Advection-Dispersion distribution work better for scenarios of low and high hydraulic conductivity, respectively.

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