Soil salinization at a side-hill seep and closed basin in southern Alberta

1993 ◽  
Vol 73 (2) ◽  
pp. 209-222 ◽  
Author(s):  
J. J. Miller ◽  
G. J. Beke ◽  
S. Pawluk
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Shallow Groundwater ◽  
Soil Salinization ◽  
Upward Movement ◽  
Soluble Salts ◽  
Shallow Water Table ◽  
Soil Extracts ◽  
Closed Basin ◽  
Southern Alberta

One saline soil in a side-hill seep and another in a closed basin in southern Alberta were investigated using hydrological, chemical and mineralogical techniques to compare the nature of soil salinization. The morphology of the saline Gleyed Regosolic soil in the seep indicated strong upward movement of water and soluble salts. This was evident from the presence of mottles in the soil solum, a shallow water table (≤ 2.69 m), and high EC (2.8–32.5 dS m−1) and SARt (4.8–55.5) values in the shallow groundwater and soil. High soluble Mg/Ca ratios (2.1) in the soil extract of the Ccasa3 horizon and the presence of Mg-calcites (4–5 mol %) indicated restricted leaching at this site. The morphology of the saline Orthic Dark Brown Chernozemic soil in the closed basin reflected slight upward movement of water and soluble salts. This morphology was consistent with a deeper water table (≥ 2.62 m), and lower EC (2.2–10.0 dS m−1) and SARt (2.9–11.3) values in the shallow groundwater and soil. High Mg/Ca ratios (4.8–7.0) in soil extracts of the C horizons, but no Mg-calcites, indicated greater leaching at this site. We estimated that it would take about 77 yr to salinize the soil at the seep via upward groundwater movement, and 6500 yr to salinize the soil at the closed basin. The high tritium content of the shallow groundwater at both sites suggested that downward (closed basin) and lateral (seep) movement of water to the water table was an important factor contributing to shallow water tables and soil salinization. Key words: Salinization, hydrology, chemistry, mineralogy, side-hill seep, closed basin

scholarly journals Modelling of the shallow water table at high spatial resolution using Random Forests

2019 ◽  
Author(s):  
Julian Koch ◽  
Helen Berger ◽  
Hans Jørgen Henriksen ◽  
Torben Obel Sonnenborg
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Spatial Resolution ◽  
Random Forests ◽  
Shallow Groundwater ◽  
Coefficient Of Determination ◽  
Shallow Water Table ◽  
Simple Method ◽  
Physically Based ◽  
Physically Based Modelling

Abstract. Machine learning provides a great potential to model hydrological variables at a spatial resolution beyond the capabilities of traditional physically-based modelling. This study features an application of Random Forests (RF) to model the depth to the shallow water table, for a wintertime minimum event, at 50 m resolution over a 15,000 km2 large domain in Denmark. In Denmark, the shallow groundwater poses severe risks of groundwater induced flood events affecting both, urban and agricultural areas. The risk is especially critical in wintertime, when the shallow groundwater is close to terrain. In order to advance modelling capabilities of the shallow groundwater system and to provide estimates at scales required for decision making, this study introduces a simple method to unify RF and physically-based modelling. Results from the national water resources model in Denmark (DK-model) at 500 m resolution are employed as covariate in the RF model. Thereby, RF ensures physical consistency at coarse scale and fully exhausts high-resolution information from readily available environmental variables. The vertical distance to the nearest waterbody was rated the most important covariate in the trained RF model followed by the DK-model. The validation test of the trained RF model was very satisfying with a mean absolute error of 79 cm and a coefficient of determination of 0.55. The resulting map underlines the severity of groundwater flooding risk in Denmark, as the average depth to the shallow groundwater is 1.9 m and approximately 29 % of the area is characterised with a depth less than 1 m during a typical wintertime minimum event. This study brings forward a novel method to assess the spatial patterns of covariate importance of the RF predictions which contributes to an increased interpretability of the RF model. Quantifying uncertainty of RF models is still rare for hydrological applications. Two approaches, namely Random Forests Regression Kriging (RFRK) and Quantile Regression Forests (QRF) were tested to estimate uncertainties related to the predicted groundwater levels. This study argues that the uncertainty sources captured by RFRK and QRF can be considered independent and hence, they can be combined to a total variance through simple uncertainty propagation.

Historical soil maps with a reference to redoximorphic features as basis for ecohydrological modelling.

2021 ◽  
Author(s):  
Alla Yurova ◽  
Daniil Kozlov ◽  
Maria Smirnova ◽  
Pavel Fil
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Expert Knowledge ◽  
Shallow Groundwater ◽  
Wave Form ◽  
Kinematic Wave ◽  
State Variables ◽  
Soil Maps ◽  
Shallow Water Table ◽  
Redoximorphic Features

<p>Historical soil maps with a reference to profile redoximorphic features have obvious utility for ecohydrological modelling. That is particularly pertinent in areas with shallow water tables where catchments have both dry and moist parts, latter due to moisture source from either upper or low boundary. However, there is no convenient method for converting maps to hydrological model state variables. Here we propose that the steady state continuity equation in kinematic wave form can be parameterized using expert knowledge of the typical water table depth (WTD) for soils with different hydromorphy degrees based on redoximorphic features. To test the approach, six hillslope-based computational units (catenas) were obtained, for use in simulations, by automated of the Samovetc and Izberdey catchments in the Tambov region (Russia) using lumpR software. Five of the six catenas began at poorly drained flat upslope positions with soils with various degrees of saturation by shallow groundwater and one began at a well-drained upslope position. We guided parameterization of the kinematic wave model by critical range of the WTD known to correspond to each soil group on historical soil map of hydromorphy degree. Application of expert knowledge in this manner alone yielded a broad range of possible WTD values (e.g. 1.5-5 m for a semi-hydromorphic soil) for each soil entity, but linking a catena by the fundamental physical constraint of flow continuity enabled narrowing of the range to 0.2-1 m thereby reducing it by ca. 80%. We further tested the shallow water table approximation in the WASA-SED ecohydrological model based on catenary approach to simulate soil moisture profiles referring explicitly to soil groups of different hydromorphy degree and distinguish stagnic and gleyic regimes of waterlogging. The results show that the approach could substantially improve crop and water management precision.</p>

scholarly journals Modelling of the shallow water table at high spatial resolution using random forests

2019 ◽  
Vol 23 (11) ◽  
pp. 4603-4619 ◽  
Author(s):  
Julian Koch ◽  
Helen Berger ◽  
Hans Jørgen Henriksen ◽  
Torben Obel Sonnenborg
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Spatial Resolution ◽  
Random Forests ◽  
Shallow Groundwater ◽  
Coefficient Of Determination ◽  
Shallow Water Table ◽  
Simple Method ◽  
Physically Based ◽  
Physically Based Modelling

Abstract. Machine learning provides great potential for modelling hydrological variables at a spatial resolution beyond the capabilities of physically based modelling. This study features an application of random forests (RF) to model the depth to the shallow water table, for a wintertime minimum event, at a 50 m resolution over a 15 000 km2 domain in Denmark. In Denmark, the shallow groundwater poses severe risks with respect to groundwater-induced flood events, affecting both urban and agricultural areas. The risk is especially critical in wintertime, when the shallow groundwater is close to terrain. In order to advance modelling capabilities of the shallow groundwater system and to provide estimates at the scales required for decision-making, this study introduces a simple method to unify RF and physically based modelling. Results from the national water resources model in Denmark (DK-model) at a 500 m resolution are employed as covariates in the RF model. Thus, RF ensures physical consistency at a coarse scale and fully exhausts high-resolution information from readily available environmental variables. The vertical distance to the nearest water body was rated as the most important covariate in the trained RF model followed by the DK-model. The evaluation test of the trained RF model was very satisfying with a mean absolute error of 76 cm and a coefficient of determination of 0.56. The resulting map underlines the severity of groundwater flooding risk in Denmark, as the average depth to the shallow groundwater is 1.9 m and approximately 29 % of the area is characterized as having a depth of less than 1 m during a typical wintertime minimum event. This study brings forward a novel method for assessing the spatial patterns of covariate importance of the RF predictions that contributes to an increased interpretability of the RF model. Quantifying the uncertainty of RF models is still rare for hydrological applications. Two approaches, namely random forests regression kriging (RFRK) and quantile regression forests (QRF), were tested to estimate uncertainties related to the predicted groundwater levels.

Soil texture and layering effects on water and salt dynamics in the presence of a water table: a review

2014 ◽  
Vol 22 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Xiaopeng Li ◽  
Scott X. Chang ◽  
K. Francis Salifu
Keyword(s):  
Water Table ◽  
Soil Texture ◽  
Soil Profile ◽  
Land Reclamation ◽  
Capillary Rise ◽  
Soil Salinization ◽  
Maximum Height ◽  
Upward Movement ◽  
Shallow Water Table ◽  
The Impact

Soil texture and its vertical spatial heterogeneity may greatly influence soil hydraulic properties and the distribution of water and solutes in the soil profile; therefore, they are of great importance for agricultural, environmental, and geo-engineering applications such as land reclamation and landfill construction. This paper reviews the following aspects on water and salt dynamics in the presence of a water table: (i) the effect of soil texture on the extent of upward movement of groundwater in homogenous soils and (ii) the impact of soil textural layering on water and salt dynamics. For a homogenous soil, the maximum height of capillary rise (hmax) or the evaporation characteristic length (ECL) is closely related to the soil texture. When the water table is deeper than hmax, water will evaporate at some depth below surface and salts will be retained below the evaporation front, causing the separation of water and salt. For layered soils, flow barriers (capillary and hydraulic barriers) can make the soil hold more water than a nonlayered one. A capillary barrier may work when a fine-textured layer overlies a coarse-textured layer during infiltration or a coarse-textured layer overlies a fine-textured layer during evaporation, and a hydraulic barrier may occur when a poorly permeable layer exists in the soil profile. The extra water held by flow barriers may improve water availability to plants and may at the same time increase salinization and other environmental risks. Under special conditions, such as in seasonally frozen soils with a shallow water table, there is an additional soil salinization incentive caused by freeze–thaw cycles. Above all, further research is needed to understand the complex effects of soil texture and layering on water and salt dynamics, especially in artificial soils such as reclaimed soils with contrasting properties.

scholarly journals Simulation of upward flux from shallow water-table using UPFLOW model

2013 ◽  
Vol 3 ◽  
pp. 123-127
Author(s):  
M.H. Ali ◽  
I. Abustan ◽  
S. Islam
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Capillary Rise ◽  
Coefficient Of Determination ◽  
Reliable Estimate ◽  
Graphical Display ◽  
Upward Movement ◽  
Irrigation Requirement ◽  
Shallow Water Table ◽  
Upward Flux

The upward movement of water by capillary rise from shallow water-table to the root zone is an important incoming flux. For determining exact amount of irrigation requirement, estimation of capillary flux or upward flux is essential. Simulation model can provide a reliable estimate of upward flux under variable soil and climatic conditions. In this study, the performance of model UPFLOW to estimate upward flux was evaluated. Evaluation of model performance was performed with both graphical display and statistical criteria. In distribution of simulated capillary rise values against observed field data, maximum data points lie around the 1:1 line, which means that the model output is reliable and reasonable. The coefficient of determination between observed and simulated values was 0.806 (r = 0.93), which indicates a good inter-relation between observed and simulated values. The relative error, model efficiency, and index of agreement were found as 27.91%, 85.93% and 0.96, respectively. Considering the graphical display of observed and simulated upward flux and statistical indicators, it can be concluded that the overall performance of the UPFLOW model in simulating actual upward flux from a crop field under variable water-table condition is satisfactory. Thus, the model can be used to estimate capillary rise from shallow water-table for proper estimation of irrigation requirement, which would save valuable water from over-irrigation.

Shallow Water Table Fluctuations in Relation to Soil Penetration Resistance

Ground Water ◽  
2003 ◽  
Vol 41 (7) ◽  
pp. 964-972 ◽  
Author(s):  
James B. Shanley ◽  
K. Niclas Hjerdt ◽  
Jeffrey J. McDonnell ◽  
Carol Kendall
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Penetration Resistance ◽  
Shallow Water Table ◽  
Water Table Fluctuations ◽  
Soil Penetration Resistance

Development and application of long-term root zone salt balance model for predicting soil salinity in arid shallow water table area

2019 ◽  
Vol 213 ◽  
pp. 486-498 ◽  
Author(s):  
Guanfang Sun ◽  
Yan Zhu ◽  
Ming Ye ◽  
Jinzhong Yang ◽  
Zhongyi Qu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Soil Salinity ◽  
Root Zone ◽  
Balance Model ◽  
Salt Balance ◽  
Shallow Water Table

Analysis of the contribution of groundwater to evapotranspiration in an arid irrigation district with shallow water table

2016 ◽  
Vol 171 ◽  
pp. 131-141 ◽  
Author(s):  
Zhongyi Liu ◽  
Hang Chen ◽  
Zailin Huo ◽  
Fengxin Wang ◽  
Clinton C. Shock
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Irrigation District ◽  
Shallow Water Table
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