scholarly journals Determining Hydraulic Conductivity from Soil Characteristics with Applications for Modelling Stream Discharge in Forest Catchments

10.5772/20309 ◽  
2011 ◽  
Author(s):  
Marie-France Jutras ◽  
Paul A.
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Characteristics ◽  
Stream Discharge

scholarly journals Maximum Holocene groundwater levels and associated extension of peat in the border zone of ‘Het Gooi’ (the Netherlands): a reconstruction based on the study of soil transects

2020 ◽  
Vol 99 ◽  
Author(s):  
Jan Sevink ◽  
Sander Koopman
Keyword(s):  
Hydraulic Conductivity ◽  
Sea Level ◽  
Middle Ages ◽  
Groundwater Level ◽  
Soil Characteristics ◽  
Border Zone ◽  
Maximum Extension ◽  
The Holocene ◽  
Late Middle Ages ◽  
Ridge System

Abstract The area ‘Het Gooi’ in the Netherlands is part of a Pleistocene ice-pushed ridge system that partially drowned during the Holocene upon sea level and associated groundwater rise. As a result, the ridge system was gradually encroached by peat. From the late Middle Ages onward, man reclaimed the peatlands surrounding Het Gooi, heavily reducing their extension and lowering the regional groundwater level by increasingly intensive drainage. Based on historical and archaeological arguments, several authors assume that the Holocene peat cover in the border zones of ‘Het Gooi’ formed the extension of large raised peat bogs that formed further to the west and east, respectively. They presume that in the late Middle Ages these extensions reached ‘upslope’ to a maximum altitude of 3 m + NAP (Dutch Ordnance Datum – approximating mean sea level). However, the original extension is difficult to reconstruct, as this peat has disappeared as a result of its exploitation and oxidation, if having been present at all. In this study, the maximum extension of the Holocene peat cover on the ice-pushed ridge system was reconstructed based on soil characteristics. Used soil characteristics concerned the presence of iron coatings around sand grains and the upper boundary of gleyic features, because these are indicators for the mean highest groundwater level (MHG). For peat to form, this MHG needs to be at or just above the ground surface for most of the year. Based on study of a number of soil transects, we reconstructed to what maximum altitude peat encroachment may have occurred. This ‘maximum extension’ can alternatively be described as the maximum altitude of the bottom of the peat onlapping the ridge system. In the western border zone, this peat cover was found to have reached to c. NAP or just above, near Hilversum. No indications were found for the occurrence of raised bogs. We conclude that the phreatic groundwater level in this zone was controlled by the sea level and associated lake levels (Naardermeer and Horstermeer), a dominant role being played by the shallow presence of Pleistocene formations with a high hydraulic conductivity. In the eastern border zone, altitudes were more variable and in places reached 2 m + NAP. Peat at this higher elevation probably formed under the influence of a higher phreatic groundwater level, induced by the presence of a clayey Eemian fill with low hydraulic conductivity in the adjacent glacial basin (the Eem valley). This study demonstrates the value of detailed soil transect studies for palaeogeographical reconstructions of the former Holocene peat cover in Pleistocene landscapes of NW Europe. It also provides independent data for validation of geohydrological models for such landscapes.

Microbial abundance and transport in glacial near-surface meltwater

2020 ◽  
Author(s):  
Ian Stevens ◽  
Tristram Irvine-Fynn ◽  
Arwyn Edwards ◽  
Philip Porter ◽  
Joseph Cook ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Weathering Crust ◽  
Microbial Abundance ◽  
Stream Channels ◽  
Glacier Surface ◽  
Near Surface ◽  
Transport Dynamics ◽  
Stream Discharge ◽  
Proxy Measure ◽  
Glacial Environments

<p>Glacier surfaces are active microbial ecosystems which contribute to melt feedback cycles and biogeochemical processes. Despite this recognition, there is a lack of knowledge regarding the transport dynamics and residence time of microbes in this supraglacial habitat. Throughout the ablation season, meltwater is generated across a glacier’s surface and flows through the porous near-surface weathering crust before entering the channelised supraglacial network. Within the weathering crust, solar radiation provides a “photic zone” which, combined with nutrient availability, is conducive for microbial activity. The water flow through this porous near-surface layer provides a transport mechanism for these microbes. However, the nature of controls upon this phenomenon remain unexplored, despite the relevance for cellular export to downstream ecosystems, glacier surface albedo and biogeochemical cycling.</p><p>To determine potential controls on microbial transport in the weathering crust, we present 913 measurements of microbial cell abundance in supraglacial meltwaters from 11 glaciers across the northern hemisphere. Each measurement is coupled with weathering crust hydraulic conductivity or stream discharge. These data reveal a mean microbial abundance of 2.2 × 10<sup>4</sup> cells mL<sup>-1</sup> (with a range of 10<sup>3</sup> – 10<sup>6</sup>) in supraglacial meltwaters within the weathering crust and stream channels. Modal microbe size was 1 – 2 μm (56 % of microbes), with 89 % of microbes smaller than 4 μm. No substantiated difference in size distributions between weathering crust and stream meltwaters were observed. No correlation between microbial abundance and near-surface hydraulic conductivity or stream discharge were observed, either across the entire dataset or when considered on a glacier-by-glacier basis. At three glaciers, water temperature and electrical conductivity (a proxy measure for ionic load) were also recorded; but we observe no correlation between these two variables and microbial abundance. Our data suggests weathering crust microbe abundance is consistent across differing glacial environments, and the concentrations entrained in the near-surface equal those seen in supraglacial streams. As such, despite the low transfer rate of meltwater, there appears to be limited evidence for substantial storage or accumulation of biomass in the near-surface weathering crust. Moreover, microbe entrainment does not appear to be driven by primary hydrological controls. Assuming that once liberated within the weathering crust entrained microbes reach channelised supraglacial networks, we estimate a delivery of 1.1 × 10<sup>9</sup> kg C a<sup>-1</sup> to downstream environments globally (excluding Antarctica) to 2100, using existing discharge forecasts. This study represents a crucial first step in examining microbial abundance within, and transport across glacier surfaces and their potential role in biogeochemical process-feedbacks and the inoculation of downstream environments.</p>

scholarly journals Effect of the spatial distribution of physical aquifer properties on water table depth and stream discharge in a headwater catchment

2009 ◽  
Vol 6 (6) ◽  
pp. 6929-6966
Author(s):  
C. Gascuel-Odoux ◽  
M. Weiler ◽  
J. Molenat
Keyword(s):  
Hydraulic Conductivity ◽  
Linear Relationship ◽  
Water Table ◽  
Spatial Models ◽  
Water Table Depth ◽  
Transitional Area ◽  
Stream Discharge ◽  
Crystalline Bedrock ◽  
Solute Fluxes ◽  
The Hill

Abstract. Water table depth and its dynamics is often poorly predicted upslope despite they control both water transit time within the catchment and solute fluxes at the catchment outlet. The paper analyses how relaxing the assumption of lateral homogeneity of physical properties can improve simulations of water table depth and dynamics. Four different spatial models relating of saturated hydraulic conductivity to topography have been tested: a simple linear relationship, a linear relationship with two topographic indexes, two domains with a transitional area. The Hill-Vi model has been modified to test these hypotheses. The studied catchment (Kervidy-Naizin, western France) is underlain by schist crystalline bedrock. A shallow and perennial groundwater highly reactive to rainfall events mainly develops in the weathered saprolite layer. The results indicate that 1) discharge and the water table in the riparian zone are similarly predicted with the four models, 2) distinguishing two domains constitutes the best model and slightly improves prediction of the water table upslope, and 3) including spatial variations in the other parameters such as porosity or rate of hydraulic conductivity decrease with depth does not improve the results. These results underline the necessity of better investigation of upslope areas in hillslope hydrology.

Enhanced Mualem-Van Genuchten Approach for Estimating Relative Soil Hydraulic Conductivity

2015 ◽  
Vol 725-726 ◽  
pp. 355-360 ◽  
Author(s):  
Vitaly Terleev ◽  
Vladimir Badenko ◽  
Inna Guseva ◽  
Wilfried Mirschel
Keyword(s):  
Hydraulic Conductivity ◽  
Water Retention ◽  
Soil Characteristics ◽  
Water Volume ◽  
Water Retention Capacity ◽  
Moisture Capacity ◽  
Theoretical Justification ◽  
Retention Capacity ◽  
Relative Water ◽  
Relative Hydraulic Conductivity

New theoretical justification for the function of soil differential moisture capacity (dependence of the relative water volume content on the capillary pressure) and its antiderivative is presented. New method is based on the concept of capillarity and the lognormal distribution of the effective radii of pores. Relative hydraulic conductivity of soil is calculated with usage of these functions and Mualem's approach. Hydrophysical parameters have been interpreted and evaluated on the base of some physical and statistical soil characteristics. Also the approximation for functions of water-retention capacity and relative hydraulic conductivity of soil has been proposed.

Estimation of hydrogeologic parameters and groundwater-balance components based on fluctuations of the water tables

1985 ◽  
Vol 22 (12) ◽  
pp. 1803-1812 ◽  
Author(s):  
E. Zaltsberg
Keyword(s):  
Hydraulic Conductivity ◽  
Weather Conditions ◽  
Specific Yield ◽  
Groundwater Balance ◽  
Stream Discharge ◽  
Vertical Hydraulic Conductivity ◽  
Water Tables ◽  
Groundwater Regime ◽  
Observation Wells ◽  
Experimental Basin

The Wilson Creek experimental basin is located on the slope of the Manitoba Escarpment, southwestern Manitoba. Observations of groundwater regime, weather conditions, and stream discharge were carried out in this basin from 1965 to 1980. Using groundwater fluctuations in observation wells, it was found that the values of the specific yield of till range from 0.03 to 0.04 and the specific yield of shale is equal to 0.04. Calculated vertical hydraulic conductivity of till ranges from 2 × 10−4 to 3 × 10−4 m/day.On the basis of these determinations, groundwater balances for separate segments of the watershed and for the whole of the basin were calculated. Considering the basin as a whole, it was found that the average values of groundwater-balance components during spring–summer seasons were as follows: infiltration, 111 mm or 30% of precipitation; evaporation, 58 mm or 19% of precipitation; and groundwater runoff, 61 mm or 20% of precipitation.

Effect of Ca:Mg ratio on soil sodicity at different levels of sodium adsorption ratio and electrolyte concentration

Soil Research ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 751 ◽  
Author(s):  
AR Astaraei ◽  
RPS Chauhan
Keyword(s):  
Hydraulic Conductivity ◽  
Electrolyte Concentration ◽  
Soil Characteristics ◽  
Regression Equations ◽  
Exchangeable Sodium ◽  
Loamy Soil ◽  
Water Parameters ◽  
Degree Of Dispersion ◽  
Exchange Complex ◽  
Different Levels

A laboratory study on loamy soil (19.6% clay) with different quality waters varying in Ca : Mg ratio (1 : 1, 1 : 2, 1 : 4, 1 : 6, 1 : 8) at two levels each of salinity (6 and 12 dSm-1) and SAR (10 and 50) was carried out. Exchangeable sodium (ES), exchangeable sodium percentage (ESP), Na: (Ca+Mg) ratio and degree of dispersed clay in soil increased with increasing Mg concentration at both the levels of EC(iw) and SAR(iw). The percentage of dispersed clay was more with increasing Mg concentration at higher SAR(iw) with a lower level of EC(iw), while the reverse trend was observed with hydraulic conductivity of soil. The Ca : Mg ratio in the exchange complex decreased with increasing Mg concentration, EC(iw) and SAR(iw). Further Mg concentration in the exchange complex increased with Mg in water and EC(iw) and decreased with the rise in SAR(iw). The multiple correlations between different water parameters and soil characteristics, namely ESP, degree of dispersion and hydraulic conductivity, were calculated and regression equations were developed. The relative contributions of water parameters to ESP, degree of dispersion and hydraulic conductivity of soil were in the order SAR(iw) > EC(iw) > Ca : Mg; EC(iw) > Ca : Mg > SAR(iw), EC(iw) > SAR(iw) > Ca : Mg, respectively.

Groundwater recharge and discharge response to rainfall on a hillslope

Soil Research ◽  
1986 ◽  
Vol 24 (3) ◽  
pp. 343 ◽  
Author(s):  
T Talsma ◽  
EA Gardner
Keyword(s):  
Hydraulic Conductivity ◽  
Groundwater Recharge ◽  
Soil Water ◽  
Water Table ◽  
Water Movement ◽  
Free Water ◽  
Stream Discharge ◽  
Water Tables ◽  
Hydraulic Gradients ◽  
Rainfall Recharge

Groundwater recharge was investigated within a representative hillslope segment of a small forested catchment, where the depth to the water table increased when progressing upslope from a free water outlet. Catchment soils varied with progression upslope from grey through yellow to red earths, which were underlain by low hydraulic conductivity B horizons and permeable substrata. The catchment was equipped for measuring stream discharge, rainfall characteristics, water table position, soil water content and soil hydraulic properties. Measurements commenced when soil water was severely depleted by drought, and were continued to monitor infiltration and redistribution with depth after more than 1000 mm of rainfall. Water movement occurred under approximately unit hydraulic gradients to the layer of restricted hydraulic conductivity; with movement through this layer proceeding under gradients considerably in excess of unity. Between rainfall events water movement in the soil profiles with deep water tables occurred by redistribution, with the capillary flux exceeding the gravitational flux. Where water tables were shallow (<m), profile recharge occurred within 7 weeks, after which sustained recharge to the groundwater body occurred at rates of the order of 3 mm day-1. Where water tables were deep (>7 m) it took many months for the soil water deficit to be replenished by rainfall. Recharge to groundwater in this case commenced with a flux of about 0.5 mm day-1 and decreased to an estimated value of 0.3 mm day-1 some 5 months later. Following winter rain more than 30% of the annual groundwater discharge from the catchment originated from a relatively small but expanding area near the free water outlet.

scholarly journals Effect of the spatial distribution of physical aquifer properties on modelled water table depth and stream discharge in a headwater catchment

2010 ◽  
Vol 14 (7) ◽  
pp. 1179-1194 ◽  
Author(s):  
C. Gascuel-Odoux ◽  
M. Weiler ◽  
J. Molenat
Keyword(s):  
Hydraulic Conductivity ◽  
Linear Relationship ◽  
Water Table ◽  
Spatial Models ◽  
Water Table Depth ◽  
Transitional Area ◽  
Stream Discharge ◽  
Crystalline Bedrock ◽  
Solute Fluxes ◽  
The Hill

Abstract. Water table depth and its dynamics on hillslopes are often poorly predicted despite they control both water transit time within the catchment and solute fluxes at the catchment outlet. This paper analyses how relaxing the assumption of lateral homogeneity of physical properties can improve simulations of water table depth and dynamics. Four different spatial models relating hydraulic conductivity to topography have been tested: a simple linear relationship, a linear relationship with two different topographic indexes, two Ks domains with a transitional area. The Hill-Vi model has been modified to test these hypotheses. The studied catchment (Kervidy-Naizin, Western France) is underlain by schist crystalline bedrock. A shallow and perennial groundwater highly reactive to rainfall events mainly develops in the weathered saprolite layer. The results indicate that (1) discharge and the water table in the riparian zone are similarly predicted by the four models, (2) distinguishing two Ks domains constitutes the best model and slightly improves prediction of the water table upslope, and (3) including spatial variations in the other parameters such as porosity or rate of hydraulic conductivity decrease with depth does not improve the results. These results underline the necessity of better investigations of upslope areas in hillslope hydrology.

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