The
drawdown causes an upwelling of the water table in the vicinity of the well
, whereas the cone of depression is the cone-shaped upwelling. The drawdown is the percentage of available water in the aquifer that has already been used whereas the cone of depression is the percentage of recharge water.
What is drawdown in terms of a well and groundwater What is a cone of depression?
When a public supply well is pumping,
groundwater
flow changes direction in a portion of the watershed. … The pumping well creates an artificial discharge area by drawing down (lowering) the water table around the well. This area of drawdown is called the cone of depression.
How does the pumping from the well influence drawdown in the well?
As pumping continues, the
rate of local drawdown decreases and eventually stabilizes
as the withdrawal is compensated for by inflow of groundwater from the surrounding area. As this happens, the measurable decline in the water table spreads outward.
How does a cone of depression form in the water table when pumping water from an aquifer?
When a well is pumped, the water level in the well is lowered. … As the water flows into the well,
the water levels or pressure in the aquifer around the well decrease
. The amount of this decline becomes less with distance from the well, resulting in a cone-shaped depression radiating away from the well.
What is drawdown in cone of depression?
Drawdown:
The vertical distance groundwater elevation is lowered
, due to the removal of groundwater. The distance between the static water level and the surface of the cone of depression.
How is drawdown well calculated?
Subtract the measurements you collect as the pump is running from the static water level
. The difference is the drawdown. For example, if the static water level is 1 foot below the top of the casing and the water level after one hour is 3 feet below the top of the casing, the drawdown at one hour of pumping is 2 feet.
When might a well well a go dry?
A well is said to have gone dry
when water levels drop below a pump intake
. This does not mean that a dry well will never have water in it again, as the water level may come back through time as aquifer recharge from precipitation seepage increases and/or pumping of the aquifer is lessened.
What would happen if a cone of depression extended below the bottom of a well?
If the cone of depression extends to other nearby wells,
the water level in those wells will be lowered
. The cone develops in both shallow water-table and deeper confined-aquifer systems. … Elsewhere, such as where clayey material directly overlies bedrock, a deep well extending into bedrock may be needed.
What is drawdown and how does it relate to the cone of depression quizlet?
Relate drawdown to cone of depression. Drawdown is
when the water table around a well is lowered due to withdrawalof water from the well
. The resulting depression within the water table is called a cone of depression. Explain why ground may subside after groundwater is pumped to the surface.
What is a drawdown curve?
A plot of the decline of water table or piezometric level versus distance from a pumping well
, or versus time at a given distance from a pumping well, resulting from the continuous pumping from a well discharging at a known rate.
Is cone of depression bad?
The cone of depression that develops around a well creates a local slope to the water table. The resulting hydraulic gradient may be large enough to reverse the flow direction of nearby groundwater (figure below a, b). Such reversals can allow contaminants, seeping out of a septic tank, to contaminate the well.
Which one of the following is not a cause of depression in groundwater?
The correct answer is
Afforestation
. Afforestation is the plantation of trees that facilitates proper seepage of rainfall into the ground which will lead to groundwater recharge.
How did this cone of depression in the groundwater form quizlet?
How did this cone of depression in the groundwater form?
An artesian spring flowed upward on all sides.
… Groundwater is pumped from the well faster than it can flow to replenish what is lost.
What is drawdown level?
Drawdown is
the drop in level of water in a well when water is being pumped
. Drawdown measurements record the difference (in feet or meters) between the static level and the pumping level. Well yield. Well yield is the volume of water per unit of time that is. produced from the well by pumping.
What happens during drawdown?
In surface water hydrology and civil engineering, drawdown refers to the
lowering of the surface elevation of a body of water
, the water table, the piezometric surface, or the water surface of a well, as a result of the withdrawal or water.
What can result if a well is pumped faster than it is recharged?
Pumping groundwater faster than it can recharge can
lead to dry wells
, especially during droughts. … Many areas of the United States are experiencing groundwater depletion.
