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Recharge from precipitation
Published in Ian Simmers, I. Simmers, J.M.H. Hendrickx, G.P. Kruseman, K.R. Rushton, Recharge of Phreatic Aquifers in (Semi-) Arid Areas, 2017
Jan M.H. Hendrickx, Glen R. Walker
Case 2. Gunn (1983) investigated by which mechanisms flow is concentrated and transmitted to the underlying aquifer for a karst area in the Waitomo district of New Zealand. Although his study was conducted in an area with mean annual precipitation and potential evapotranspiration of 2370 mm and 775 mm respectively, it reveals a number of horizontal flow and fracture flow mechanisms that are relevant for recharge processes in arid zones after high intensity storms. He found that closed depressions (solution dolines, sinkholes, cockpits) act as funnels and collect near surface water through three concentrating mechanisms: 1. Overland flow, defined as any water flowing along the ground surface; 2. Throughflow, defined as any water flowing laterally within the soil; and 3. Subcutaneous flow, defined as water flowing laterally through the upper, weathered layer of limestone. This is an example of localized recharge where the horizontal movement of water not only takes place at the soil surface, but also below it.
Infiltration, Throughflow, and Overland Flow
Published in Richard J. Chorley, Introduction to Physical Hydrology, 2019
Throughflow, travelling through soil pore spaces rather than over the ground surface, moves at very much lower velocities than overland flow. Rates of 20–30 cm/hr for throughflow are of the order of a thousand times lower than overland flow rates, so that periods of about 1,000 hours rainfall are needed for a steady state of flow to be achieved throughout an average basin. In practice, such a steady state is never attained for throughflow, and equation (2) for overland flow must be replaced with equation (3) for throughflow:
Uranium in animals, vegetables and minerals: landscape geochemical and biogeochemical expressions of the Four Mile West sedimentary uranium deposit, South Australia
Published in Australian Journal of Earth Sciences, 2020
S. M. Hill, S. B. Hore, V. J. Normington
The landform expression of faults, and most especially faulted blocks, in the area show subdued, low-relief, down-faulted blocks of sediment preservation that are more conducive to preserving mineralisation as well as groundwater (and surface water) throughflow. In contrast, upfaulted blocks that are now more topographically prominent as erosional rises are more likely to have had any mineralised parts of the sequence eroded and/or removed by oxidation. It is this faulting that in part helps explain the geometry and constrains the extent of mineralisation. For example, the division between Four Mile West and Four Mile East is largely due to an upfaulted block that now exposes oxidised Mesozoic sediments along a corresponding low ridge between the ore bodies. The down-faulted block at Four Mile West preserves the Mesozoic and Cenozoic sedimentary sequence and its lower-lying setting has helped to ensure the entire sequence is less eroded and oxidised. This low-lying area is easy to recognise also because it corresponds to an embayment within the range front associated with the Paralana Fault zone along the eastern Flinders Ranges. This embayment represents the area where the NW–SE-trending structures responsible for the down-throw of the Four Mile West mineralisation cross-cut and displace the Paralana Fault and associated range front. A regional examination of similar, range-front embayments could be an important component of a regional reconnaissance exploration targeting exercise.
Non-linear flow through rockfill embankments
Published in Journal of Applied Water Engineering and Research, 2019
Ganesh H. R. Ravindra, Fjóla G. Sigtryggsdóttir, Øyvind A. Høydal
Further, the flume sidewalls for both setups were sloped at 1:1 transforming the flume cross-section to a trapezoidal profile. This was done to account for the steep abutment profile observed at the test location in Rossvatn, Norway which resulted in a trapezoidal channel cross-section. For model setup M2, a total of 7 piezometers were positioned along the centerline of the dam sections with uniform spacing of 0.3 m for throughflow depth measurements and 2 piezometers were placed upstream of the test dam sections for water level measurements. For M3, 5 piezometers with even spacing of 0.5 m were installed within the embankment structures of the test dams and a single piezometer was installed upstream of the test embankments. Construction details of the experimental setup were obtained from EBL Kompetanse (2006).
Water resources planning in a drying climate in the south-west of Western Australia
Published in Australasian Journal of Water Resources, 2022
Kathleen Broderick, Don McFarlane
Such was the concern about the quantity and quality of groundwater and throughflow wetlands, the Perth Urban Water Balance Study developed an understanding and model of groundwater under Perth (Cargeeg et al. 1987). A conclusion reached in the study was that water-level variations within the groundwater system of the Perth region are dominated by climate, a surprising finding given the degree to which urbanisation affects the water cycle. It emphasises the strength of climate change signal in the south-west of WA.