問題一覧
1
Soils are _____ due to the existence of interconnected voids through which water can flow from points of high energy to points of low energy.
permeable
2
read the importance of hydrogeology
done
3
it is the cycle of changes and movements that surface water and shallow groundwater repeatedly passes through.
hydrologic cycle
4
it is the study of the groundwater phase of the hydrologic cycle (both surface and subsurface) related to the effects of geophysical features of soil and rock formations.
hydrogeology
5
snow or rain that reaches the earth's surface tends to either flow over the ground surface as dictated by gravity or to infiltrate into the ground.
precipitation
6
infiltrating water that continue to migrate due to gravity effects is drawn to the underground zone.
infiltration
7
tends to reflect the surface topography of the area, being at higher elevation where the ground surface is high and at a lower elevation where the ground surface is low.
water table or phreatic surface
8
soil zone above the phreatic surface, pore water pressure is negative.
vadose zone
9
may be either relatively stationary or mobile (that is, underground flow is occurring)
groundwater
10
One of the major physical parameters of a soil that controls the rate of seepage through it is hydraulic conductivity,
permeability
11
the total head at a point in water under motion can be given by the sum of the pressure, velocity, and elevation heads. the total head at a point in water under motion can be given by the sum of the pressure, velocity, and elevation heads.
bernoulli’s equation
12
In ____, Darcy published a simple equation for the discharge velocity of water through saturated soils, which may be expressed as ____.
1856, v=ki
13
is a physical property which measures the ability of the material to transmit fluid through pore spaces and fractures in the presence of an applied hydraulic gradient.
hydraulic conductivity
14
hydraulic conductivity depends on several factors: page 11
done
15
typical values of hydraulic conductivity of saturated soils.
done
16
the ability of water (or other fluid) to flow through a soil by traveling through the void spaces.
permeability
17
factors affecting flow of permeability: page 13
done
18
it controls the amount of fluid discharge of a channel and its ability to move sediments. This is a measure of channel flow efficiency.
hydraulic radius
19
the ratio of the cross-sectional area of fluid flow, A, to the length of the wetted perimeter.
hydraulic radius
20
formula of hydraulic radius, Rh
done
21
what are the two standard laboratory tests that are used to determine the hydraulic conductivity of soil.
constant-head test and falling-head test
22
In this type of laboratory setup, the water supply at the inlet is adjusted in such a way that the difference of head between the inlet and the outlet remains constant during the test period.
constant-head test
23
The total volume of water collected may be expressed as:
done
24
Water from a standpipe flows through the soil. The initial head difference h1 at time t = 0 is recorded, and water is allowed to flow through the soil specimen such that the final head difference at time t = t2 is h2.
falling-head test
25
The rate of flow of the water through the specimen at any time t can be given by:
done
26
Most soils are not isotropic with respect to permeability. In a given soil deposit, the magnitude of _ changes with respect to the direction of flow.
k
27
indicates that adjacent paths of water particles are parallel, even when changing direction, and the paths never cross.
laminar flow