Diurnal groundwater level fluctuations in sandy till — A model analysis

Johansson, Per-Olof

doi:10.1016/0022-1694(86)90118-6

Cited by 15 publications

(8 citation statements)

References 4 publications

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“…10). The continuous recordings of the groundwater levels at R11 and R15 showed smooth changes and no diurnal variations were obtained as observed in another part of the study area (Johansson 1986). Spring discharge and groundwater level showed high linear correlation for both springs (Rostock: discharge-R2, ?…”

Section: Prolonged and Expanded Investigations At Rostock And Gri5n Ksupporting

confidence: 54%

Spring Discharge and Aquifer Characteristics in a Sandy Till Area in Southeastern Sweden

Johansson¹

1987

Hydrology Research

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Spring discharge and groundwater levels were used to study groundwater outflow recessions, groundwater reservoir sizes, water yielding properties and saturated hydraulic conductivities in a sandy till area in southeastern Sweden. Water chemistry was used as an indicator of flow paths. The catchment areas of the five springs, ranging from approximately 0.01 km2 to 0.2 km2 in size, were all mainly covered with coniferous forest. The maximum active groundwater storages of the catchment areas of the springs varied from 75 to 145 mm. As a comparison the maximum total groundwater storage of the till in the catchment area of the largest spring was estimated to 1,250 mm. Two springs were chosen for detailed studies. The highest peak discharge of the smallest of these springs was 1.7 mm/day and it usually dried up in summer. The discharge from the largest spring was evenly distributed and varied between 0.2 and 0.8 mm/day. Frequent analyses of water chemistry during a spring with intense snowmelt revealed no change of water composition in spite of a great increase in discharge; for the smallest spring by more than 30 times. Integrated values of the specific water release from the unsaturated zone to the groundwater reservoir were calculated from runoff volumes and decreasing groundwater levels for the catchment area of the largest spring. The different values obtained from dry summer and winter periods, 0.024 and 0.047 respectively, indicated a strong influence from evapotranspiration. It the same spring, an areally integrated value of the saturated hydraulic conductivity was estimated to 6 × 10−5 m/s from a linearized solution of the Boussinesq equation.

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Section: Prolonged and Expanded Investigations At Rostock And Gri5n Ksupporting

confidence: 54%

Spring Discharge and Aquifer Characteristics in a Sandy Till Area in Southeastern Sweden

Johansson¹

1987

Hydrology Research

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“…These requirements are more likely to be met on coarse sediments in which saturated conductivity is high and in coastal positions where the water tables are shallow, in agreement with our observations. Two indicators of groundwater uptake by plants, diurnal water table fluctuations and groundwater salinization (Johansson, 1986; Heuperman, 1999; Sapanov, 2000) suggested that E. grandis plantations use groundwater in coarse textured soils. Detailed continuous measurements of groundwater level in an E. grandis plantation on coarse textured soils manifested diurnal fluctuations of ∼2 cm between night highs and midday lows (M. Nosetto and N. Tesón, unpublished data).…”

Section: Discussionmentioning

confidence: 99%

Land‐use change and water losses: the case of grassland afforestation across a soil textural gradient in central Argentina

Nosetto

Jobbágy

Paruelo

2005

Global Change Biology

207

130

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Vegetation changes, particularly those involving transitions between tree-and grassdominated covers, often modify evaporative water losses as a result of plant-mediated shifts in moisture access and demand. Massive afforestation of native grasslands, particularly important in the Southern Hemisphere, may have strong yet poorly quantified effects on the hydrological cycle. We explored water use patterns in Eucalyptus grandis plantations and the native humid grasslands that they replace in Central Argentina. In order to uncover the interactive effects that land cover type, soil texture and climate variability may have on evaporative water losses and water use efficiency, we estimated daily evapotranspiration (ET) in 117 tree plantations and grasslands plots across a soil textural gradient (clay-textured Vertisols to sandy-textured Entisols) using radiometric information from seven Landsat scenes, existing timber productions records, and 13 C measurements in tree stems. Tree plantations had cooler surface temperatures (À5 1C on average) and evaporated more water ( 1 80% on average) than grasslands at all times and across all sites. Absolute ET differences between grasslands and plantations ranged from $ 0.6 to 2 mm day À1 and annual up-scaling suggested values of $ 630 and $ 1150 mm yr À1 for each vegetation type, respectively. The temporal variability of ET was significantly lower in plantations compared with grasslands (coefficient of variation 36% vs. 49%). Daily ET increased as the water balance became more positive (accumulated balance for previous 18 days) with a saturation response in grassland vs. a continuous linear increase in plantations, suggesting lower ecophysiological limits to water loss in tree canopies compared with the native vegetation. Plantation ET was more strongly affected by soil texture than grassland ET and peaked in coarse textured sites followed by medium and fine textured sites. Timber productivity as well as 13 C concentration in stems peaked in medium textured sites, indicating lower water use efficiency on extreme textures and suggesting that water limitation was not responsible for productivity declines towards finer and coarser soils. Our study highlighted the key role that vegetation type plays on evapotranspiration and, therefore, in the hydrological cycle. Considering that tree plantations may continue their expansion over grasslands, problematic changes in water management and, perhaps, in local climate can develop from the higher evaporative water losses of tree plantations.

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“…A one-dimensional soil water and heat flow model (SOIL) developed by Jansson and Halldin [1979] was used for the transient flow simulations. This model has been developed for hydrological conditions prevailing in the Nordic countries and has been applied in a number of studies [e.g., Jansson and Thoms-Hjiirpe, 1986; Johansson, 1986Johansson, , 1987Johnsson and Lundin, 1991]. A detailed technical description of SOIL can be found in the work by Jansson and Halldin [ 1980].…”

Section: Transient Flow Modelmentioning

confidence: 99%

Applicability of the Steady State Flow Assumption for Solute Advection in Field Soils

Destouni¹

1991

Water Resources Research

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A comparison between solute travel times predicted by a transient and a steady state flow model is made. Data for five different soil profiles with detailed measurements of their hydraulic properties and their variation with depth are used. Daily measurements of meteorological data are used as input parameters in the transient simulations that include snow and frost dynamics, interception of precipitation, and evapotranspiration. The parameters of the steady state flow model are related to the measured soil properties and the hydrological characteristics of each transient simulation. Furthermore, the influence of solute injection time on the predicted travel time is analyzed, and the effect of root water uptake on the applicability of the steady state flow assumption for solute advection is investigated. The results indicate that the steady state flow model may provide estimates of the mean solute advection that are compatible with those of the transient flow model. The constant rate of recharge in the steady state flow model should then be interpreted as the average annual effective infiltration (i.e., infiltration minus actual evapotranspiration). When root water uptake is accounted for, an arithmetic depth-averaging of the soil parameters appears to yield steady state estimates of arrival time that are closest to the transient predictions. When root water uptake is neglected, a harmonic depth-averaging of the soil parameters provides the best steady state results. The discrepancy between the arrival times predicted with the two flow models decreases with the travel distance from the soil surface. INTRODUCTIONSolute transport in field soils under natural weather conditions is generally a complex process. Any transport model, however detailed and sophisticated mathematically and numerically, is still a simplification of reality. In addition, a correct estimation of the required input parameters under field conditions is often a major problem so that simple models with fewer system parameters may in some cases be t•eferable to more intricate ones. Numerical solutions of transient flow in the unsaturated zone, and of the transport equation with time-dependent advection term, are complex and require excessive input information of both weather and soil properties. Furthermore, spatial heterogeneity in natural fields often further .complicates the solution and increases the need for input information. Thus, although water flow close to the soil .•urface is in general highly transient, many investigators of solute transport in the unsaturated zone have used the s.implifying assumption of steady state flow [e.g., van Gen-•chten and Wierenga, 1976; Bresler and Dagan, 1981; Jl•ry, t982: Small and Mular, 1987; van der Zee and van Riemsd-4/L 1987; Butters and JIo'y, 1989; Destouni and Cvetkovic, 1991]. In addition, experimental studies of transport processes in soils are often conducted under steady state flow coMitions [e.g., Gaudet et al., 1977; Nkedi-Kizza et al., 1983; Jur3' et al., 1986; Wierenga and van Genuchten, 19...

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Diurnal groundwater level fluctuations in sandy till — A model analysis

Cited by 15 publications

References 4 publications

Spring Discharge and Aquifer Characteristics in a Sandy Till Area in Southeastern Sweden

Spring Discharge and Aquifer Characteristics in a Sandy Till Area in Southeastern Sweden

Land‐use change and water losses: the case of grassland afforestation across a soil textural gradient in central Argentina

Applicability of the Steady State Flow Assumption for Solute Advection in Field Soils

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