Effect of soil disturbance on recharging fluxes: case study on the Snake River Plain,Idaho National Laboratory,USA |
| |
| Authors: | John R Nimmo Kim S Perkins |
| |
| Institution: | (1) US Geological Survey, 345 Middlefield Rd., MS-421, Menlo Park, CA 94025, USA |
| |
| Abstract: | Soil structural disturbance influences the downward flow of water that percolates deep enough to become aquifer recharge. Data from identical experiments in an undisturbed silt-loam soil and in an adjacent simulated waste trench composed of the same soil material, but disturbed, included (1) laboratory- and field-measured unsaturated hydraulic properties and (2) field-measured transient water content profiles through 24 h of ponded infiltration and 75 d of redistribution. In undisturbed soil, wetting fronts were highly diffuse above 2 m depth, and did not go much deeper than 2 m. Darcian analysis suggests an average recharge rate less than 2 mm/year. In disturbed soil, wetting fronts were sharp and initial infiltration slower; water moved slowly below 2 m without obvious impediment. Richards’ equation simulations with realistic conditions predicted sharp wetting fronts, as observed for disturbed soil. Such simulations were adequate for undisturbed soil only if started from a post-initial moisture distribution that included about 3 h of infiltration. These late-started simulations remained good, however, through the 76 d of data. Overall results suggest the net effect of soil disturbance, although it reduces preferential flow, may be to increase recharge by disrupting layer contrasts. |
| |
| Keywords: | Recharge Unsaturated zone USA Waste disposal Hydraulic properties |
| 本文献已被 SpringerLink 等数据库收录！ |
|
