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The Geosphere and Geochemistry
Published in Stanley E. Manahan, Environmental Chemistry, 2022
The water table (Figure 14.8) is crucial in explaining and predicting the flow of wells and springs and the levels of streams and lakes. It is also an important factor in determining the extent to which pollutant and hazardous chemicals underground are likely to be transported by water. The water table can be mapped by observing the equilibrium level of water in wells, which is essentially the same as the top of the saturated zone. The water table is usually not level but tends to follow the general contours of the surface topography. It also varies with differences in permeability and water infiltration. The water table is at surface level in swamps and frequently above the surface where lakes and streams are encountered. The water level in such bodies may be maintained by the water table. Influent streams or reservoirs are located above the water table; they lose water to the underlying aquifer and cause an upward bulge in the water table beneath the surface water.
Groundwater
Published in Duncan C. Wyllie, Rock Slope Engineering, 2017
Water is added or removed from the hole to change the water level by about 1–2 m (3–7 ft) and the rate at which the water level recovers to the equilibrium level is measured. For the test shown in Figure 6.14a, the hydraulic conductivity K is calculated from the following general relationship: K=AF(t2−t1)·ln(h1h2)forLR>8 where F is the shape factor. For a drill hole with radius R and a test zone of length L, the shape factor is given F=2π·Lln(L/R)
The Geosphere and Geochemistry
Published in Stanley Manahan, Environmental Chemistry, 2017
The water table (Figure 14.8) is crucial in explaining and predicting the flow of wells and springs and the levels of streams and lakes. It is also an important factor in determining the extent to which pollutant and hazardous chemicals underground are likely to be transported by water. The water table can be mapped by observing the equilibrium level of water in wells, which is essentially the same as the top of the saturated zone. The water table is usually not level but tends to follow the general contours of the surface topography. It also varies with differences in permeability and water infiltration. The water table is at surface level in the vicinity of swamps and frequently above the surface where lakes and streams are encountered. The water level in such bodies may be maintained by the water table. Influent streams or reservoirs are located above the water table; they lose water to the underlying aquifer and cause an upward bulge in the water table beneath the surface water.
One-dimensional analytical model for thermo-hydro-mechanical coupling behaviour of hydrates overlying layer during gas production
Published in Marine Georesources & Geotechnology, 2021
Bin Zhu, Songqing Yang, Lujun Wang, Deqiong Kong
During gas production, gas hydrates layer decomposes upon temperature reaching the phase equilibrium level, defined by (Kamath et al. 1987) where pe (kPa) and Te (K) denote the pressure and temperature satisfying phase equilibrium equation for hydrate decomposition reaction, respectively.