scholarly journals Impacts of three-dimensional nonuniform flow on quantification of groundwater-surface water interactions using heat as a tracer

2016 ◽  
Vol 52 (9) ◽  
pp. 6851-6866 ◽  
Author(s):  
Jonathan Reeves ◽  
Christine E. Hatch
Keyword(s):  
Surface Water ◽  
Three Dimensional ◽  
Nonuniform Flow ◽  
Heat As A Tracer

Microscale Variability of Atrazine and Chloride Leaching Under Field Conditions

1997 ◽  
Vol 11 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Guy A. Chammas ◽  
John L. Hutson ◽  
Jonathan J. Hart ◽  
Joseph M. DiTomaso
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
Simulation Models ◽  
Field Conditions ◽  
Nonuniform Flow ◽  
High Background ◽  
Sampling Schemes ◽  
Atrazine Concentration ◽  
Herbicide Transport ◽  
Chloride Leaching

Pesticide leaching experiments using widely spaced sampling sites may not adequately characterize chemical leaching behavior such as nonuniform flow between sampling points. We conducted this study to determine the three-dimensional variability of atrazine and chloride movement within a small volume of soil (2,700 cm1) under field conditions. A 1-m2area of Williamson silt loam (coarse-silty, mixed, mesic, Typic Fragiochrept) was sprayed uniformly with atrazine (1.1 kg ai/ha) and chloride (80 kg/ha). We used the Leaching Estimation and Chemistry Model (LEACHM) to simulate chemical movement. After 6.5 cm of rainfall during a 29-d period, we sampled 36 squares (5 by 5 cm) in the central 30- by 30-cm portion of the treated area at six depth increments (0 to 2, 2 to 5, 5 to 10, 10 to 15, 15 to 21, and 21 to 30 cm) and determined atrazine and Cl−concentrations. We recovered 26% of the applied atrazine and 138% of the applied chloride. Low atrazine recovery may have been due to leaching beyond 30 cm and/or degradation while excess chloride recovery is attributed to high background concentrations. Coefficients of variation (CVs) for atrazine significantly increased with depth and ranged from 26 to 353%, while CVs for Cl−were independent of depth and ranged from 32 to 66%. Derived atrazine concentration isograms illustrated highly nonuniform herbicide transport. Although LEACHM overestimated atrazine movement in the upper 15 cm, it was fairly accurate in the lower 15 cm. The overall trend in Cl−flow was adequately predicted, even though the predicted Cl−concentrations were underestimated. LEACHM could not accurately predict nonuniform flow or the variability in solute concentrations between points. However, its prediction of the atrazine center of mass (about 4.7 cm) agreed well with the derived isograms. These findings demonstrate that localized nonideal solute transport may be missed in larger sampling schemes and in simulation models.

Development, verification and validation of a three-dimensional groundwater flow model for ESM

2020 ◽  
Author(s):  
Yosuke Miura ◽  
Kei Yoshimura
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Arid Region ◽  
Flow Model ◽  
Three Dimensional ◽  
Central Valley ◽  
Groundwater Flow Model ◽  
The World ◽  
Semi Arid Region ◽  
Semi Arid

<p>  Groundwater is one of the important water resources in the world and Groundwater flow is linked with surface water strongly. Many studies on groundwater are conducted in a local scale or focused on affect-ing surface water in a global scale. In current Earth System Model, fixed and constant one-dimensional vertical grid is used in unsaturated zone. In real world, the thickness of unsatu-rated zone depends on the climate and it is considered that there are limitations of runoff process expression especially in humid mountainous area. In this study, we developed three-dimensional groundwater flow model as ESM which can represent the variably saturated flow and groundwa-ter storativity. Since, this model is eventually coupled with Land Surface Model, it is possible to track the underground water flow using boundary conditions of recharge and surface water level.</p><p>  We verified accuracy of the code using one & two-dimensional infiltration problem, three-dimensional groundwater pumping problem, and hillslope problem. Our model was com-pared with other researchers results, experimental data, analytical solutions. In consequence, our model was able to get accurate results. Subsequently, we conducted validation in Central valley, California, USA. The reason of chose this region is that this region is a semi-arid region, ground-water is used for irrigation and well pumping data is accessible. Over the world, groundwater use is more important in arid or semi-arid region than in humid area, and also highly utilized as agri-cultural water. Central valley has representativeness of groundwater use. In addition, the famous groundwater model, MODFLOW, was used to evaluate water resource management in this region. As well as MODFLOW, we calibrated hydraulic conductivity with 24 observation sites during 1961 - 2003 to validate. 156 observation points excluded 24 calibration points were used as vali-dation in same period. In the near future, we will confirm the difference between one-dimension and three dimensions setting of the unsaturated zone with respect to runoff process.</p>

LOW FLUX LIMITATIONS ON THE USE OF HEAT AS A TRACER IN GROUNDWATER-SURFACE WATER INTERACTIONS

2018 ◽  
Author(s):  
Thomas J. Glose ◽  
◽  
Christopher S. Lowry ◽  
Mark B. Hausner
Keyword(s):  
Surface Water ◽  
Heat As A Tracer
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