What is Leakance?
for all confined aquifers. It defines the degree of hydraulic connection between aquifers and is dependent on the physical properties of the sediment that makes up the confining unit. Vertical leakance is defined as the average vertical hydraulic conductivity of the confining unit sediment divided by its thickness.
What is reciprocal of hydraulic resistance?
The hydraulic resistance also called reciprocal coefficient or resistance against vertical flow, is a property of semi-confined aquifers. It is the ratio of the saturated thickness of the semi-pervious layer D’ and the hydraulic conductivity of the semi-pervious layer for vertical flow K’, hence D’/K’.
What is transmissivity in groundwater?
Transmissivity describes the ability of the aquifer to transmit groundwater throughout its entire saturated thickness (Figure 7). Transmissivity is measured as the rate at which groundwater can flow through an aquifer section of unit width under a unit hydraulic gradient.
Does sand have high hydraulic conductivity?
Relative properties Because of their high porosity and permeability, sand and gravel aquifers have higher hydraulic conductivity than clay or unfractured granite aquifers.
What is hydraulic gradient?
The hydraulic gradient (1) is the slope of the water table or potentiometric surface, that is, the change in water level per unit of distance along the direction of maximum head decrease. The hydraulic gradient is the driving force that causes groundwater to move in the direction of maximum decreasing total head.
How is groundwater transmissivity calculated?
If the aquifer is saturated up to 30 m, then the transmissivity is T30 = 30 × 3 = 90 m2/day. 2. If saturation reaches to 40 m, then additional transmissivity will come from the second layer as 10 × 6 = 60 m2/day. Hence, total transmissivity is T40 = T30 + 60 = 90 + 60 = 150 m2/day.
What are the terms related to groundwater?
The name “alluvial” refers to the loose, unlayered nature of the material – often silt, clay, sand, and gravel, deposited by running water in and around rivers. Aquifer – a geologic formation(s) that is water bearing. Confined aquifer – an aquifer below the land surface that is saturated with water.
Which material has highest hydraulic conductivity?
Which soil has highest hydraulic conductivity?
The soil with the steeper slope (the sandy soil in figure 3) has the higher hydraulic conductivity. Hydraulic conductivity (or slope “K”) defines the proportional relationship between flux and hydraulic gradient, or in this case, of unidirectional flow in saturated soil.
What is the formula of hydraulic gradient?
The hydraulic gradient is the change in total head divided the distance over which the change occurs. average pore water velocity v = -K/n(∆h/∆L) The average velocity of the water is the Darcy equation divided by the porosity of the sediment.
What is hydraulic gradient of groundwater?
How is well transmissivity calculated?
Define transmissivity mathematically. We have T = KhD where T is the transmissivity, Kh is the average horizontal conductivity and D is the aquifer thickness. Determine the units of measure for transmissivity. The horizontal conductivity is measured in length per unit time and the aquifer thickness is a length.