A transient flux model for convective infiltration: Forward and inverse solutions for chloride mass balance studies

Ginn, Timothy R.; Murphy, Ellyn M.

doi:10.1029/97wr01618

Cited by 31 publications

(33 citation statements)

References 39 publications

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“…Distinct unsaturated zone geochemical profiles relating to water transport may be preserved as a result of high evapotranspiration in arid and semi-arid regions (Ginn and Murphy 1997;Edmunds and Tyler 2002). Among the geochemical tracers in arid and semi-arid region unsaturated zones, chloride has been the most widely employed chemical marker (Scanlon et al 2006).…”

Section: Introductionmentioning

confidence: 99%

“…For instance, the generalized chloride mass balance (GCMB) method was developed based on the conventional CMB method (Murphy et al 1996;Ginn and Murphy 1997). In the GCMB technique both water and chloride transient fluxes over the land surface are considered.…”

Section: Introductionmentioning

confidence: 99%

“…For example, comparisons between chloride profiles and such instrumental records as rainfall, river flow have been made in studies in Senegal and Cyprus (Edmunds and Walton 1980;Cook et al 1992;Edmunds et al 1992). Ginn and Murphy (1997) applied the GCMB method to data from the Cyprus chloride profile presented by Cook et al (1992) and gave a brief analysis on the relationship between annual precipitation and recharge rates over 18 years. Ng et al (2009) combined chloride-based recharge estimates and numerical model predictions to identify the mechanisms controlling diffuse recharge and achieve recharge history at interannual timescales, in spite of the fact that this approach requires a great variety of parameters that are unavailable for modeling in many cases.…”

Section: Introductionmentioning

confidence: 99%

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Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

Deng¹,

Wang²,

Cai³

et al. 2015

Terr. Atmos. Ocean. Sci.

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Understanding the processes and rates of groundwater recharge in arid and semi-arid areas is crucial for utilizing and managing groundwater resources sustainably. We obtained three chloride profiles of the unsaturated-zone in the desert/loess transition zone of northwestern China and reconstructed the groundwater recharge variations over the last 11, 21, and 37 years, respectively, using the generalized chloride mass balance (GCMB) method. The average recharge rates were 43.7, 43.5, and 45.1 mm yr -1 , respectively, which are similar to those evaluated by the chloride mass balance (CMB) or GCMB methods in other semi-arid regions. The results indicate that the annual recharge rates were not in complete linear proportion to the corresponding annual precipitations, although both exhibited descending tendencies on the whole. Comparisons between the daily precipitation aggregate at different intensity and recharge rates reveal that the occurrence of relatively heavy daily precipitation per year may contribute to such nonlinearity between annual precipitation and recharge. The possible influences of vegetation cover alterations following precipitation change cannot be excluded as well. The approximately negative correlation between the average annual recharge and temperature suggests that changes in temperature have had significant influences on recharge.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

Deng¹,

Wang²,

Cai³

et al. 2015

Terr. Atmos. Ocean. Sci.

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“…This site is not located near a power plant and is in a region of eolian deposition of fine sand and silt. The precipitation and recharge rates are much higher at the Washtucna site (Ginn and Murphy 1997). The Cl/Br ratios above the chloride peak are much lower than values at the proposed ILAW Disposal Site.…”

Section: B423 Cl/br Ratiosmentioning

confidence: 92%

“…An additional assumption of steady state water flux throughout the column is often invoked, but as shown by Ginn and Murphy (1997) Over the Holocene the geographic latitude represents a long-term average of the frequent fluctuations in the geomagnetic latitude (Merrill and McElhinny 1983). Below the bomb pulse, the average 36 Cl/Cl ratio between depths 2.4 and 4.8 m was 911 x 10 -15 .…”

Section: B422 Chloride Mass Balancementioning

confidence: 99%

Performance Assessment

1999

International Oil Spill Conference Proceedings

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SummaryLockheed Martin Hanford Company (LMHC) is designing and assessing the performance of disposal facilities to receive radioactive wastes that are currently stored in single -and double -shell tanks at the Hanford Site. The preferred method of disposing of the portion that is classified as immobilized lowactivity waste (ILAW) is to vitrify the waste and place the product in near-surface, shallow-land burial facilities. The LMHC project to assess the performance of these disposal facilities is known as the Hanford ILAW Performance Assessment (PA) Activity, hereafter called the ILAW PA project. The goal of this project is to provide a reasonable expectation that the disposal of the waste is protective of the general public, groundwater resources, air resources, surface-water resources, and inadvertent intruders. Achieving this goal will require predictions of contaminant migration from the facility. To make such predictions will require estimates of the fluxes of water moving through the sediments within the vadose zone around and beneath the disposal facility. These fluxes, loosely called recharge rates, are the primary mechanism for transporting contaminants to the groundwater.Pacific Northwest National Laboratory (PNNL) assists LMHC in their performance assessment activities. One of the PNNL tasks is to provide estimates of recharge rates for current conditions and long-term scenarios involving the shallow-land disposal of ILAW. Specifically, recharge estimates are needed for a fully functional surface cover, the cover sideslope, and the immediately surrounding terrain. In addition, recharge estimates are needed for degraded cover conditions. The temporal scope of the analysis is 10,000 years, but could be longer if some contaminant peaks occur after 10,000 years.The elements of this report compose the Recharge Data Package, which provides estimates of recharge rates for the scenarios being considered in the 2001 PA. Table S.1 identifies the surface features and time periods evaluated. The most important feature, the surface cover, is expected to be the modified RCRA Subtitle C design. This design uses a 1-m-thick silt loam layer above sand and gravel filter layers to create a capillary break. A 0.15-m-thick asphalt layer underlies the filter layers to function as a backup barrier and to promote lateral drainage. Cover sideslopes are expected to be constructed with 1V:10H slopes using sandy gravel. The recharge estimates for each scenario were derived from lysimeter and tracer data collected by the ILAW PA and other projects and from modeling analyses.For the best estimate case, we proposed using a recharge rate of 0.1 mm/yr for the surface cover with a shrub-steppe plant community. This rate is lower than the cover design goal of 0.5 mm/yr because it is closer to the actual drainage rate measured with lysimeters and inferred with modeling. The simulation results showed that erosion of 20% of the silt loam layer did not impair this performance nor did the deposition of 20 cm of dune sand. For the sandy grav...

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A comparison of groundwater recharge estimation methods in a semi-arid, coastal avocado and citrus orchard (Ventura County, California)

Grismer¹,

Bachman²,

Powers³

2000

Hydrol. Process.

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A transient flux model for convective infiltration: Forward and inverse solutions for chloride mass balance studies

Cited by 31 publications

References 39 publications

Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

Performance Assessment

A comparison of groundwater recharge estimation methods in a semi-arid, coastal avocado and citrus orchard (Ventura County, California)

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