What is a specific yield?
Specific yield is defined as the ratio of (1) the volume of water that a srturated rock or soil will yield by gravity to (2) the total volume of the rock or soil. Specific yield is usually expressed as a percentage.
What is sum of the specific yield and specific retention?
Specific yield The fraction of water held back in the aquifer is known as specific retention. Thus it can be said that porosity is the sum of specific yield and specific retention.
What is the relation between porosity specific yield and specific retention?
The relationship between specific yield, specific retention and porosity is expressed by the equation: All three terms in the equation are expressed as percentages of the total volume of the rock. The specific retention decreases with increasing grain size in unconsolidated sediments (Figure 16).
What is the formula of specific yield?
The specific yield is the volume of water pumped during the test divided by the gross volume of dewatered material within the cone of depression.
What is the difference between specific storage and storativity?
For a confined aquifer or aquitard, storativity is the vertically integrated specific storage value. Specific storage is the volume of water released from one unit volume of the aquifer under one unit decline in head.
Does specific yield have units?
Specific Yield (Sy) is the volume of water removed from a unit volume of an unconfined aquifer for a unit drop in water level; this quantity is also defined as the volume of water that will drain by gravity from a saturated unit volume of an aquifer and is equivalent to the effective porosity [−].
Do good aquifers have high specific yield?
Thus, specific yield, which is sometimes called effective porosity, is less than the total porosity of an unconfined aquifer (Bear 1979)….Representative Values.
| Material | Specific Yield (%) |
|---|---|
| Gravel, fine | 28 |
| Sand, coarse | 30 |
| Sand, medium | 32 |
| Sand, fine | 33 |
What is specific yield of a well?
The Specific yield of WELL = specific capacity OF WELL = option D, Unit is m3/sec/m2/m or in short per second. (1/sec). Hence, discharge of well = sp. capacity x volume.
What does high hydraulic conductivity mean?
DEFINITIONS OF HYDRAULIC CONDUCTIVITY In theoretical terms, hydraulic conductivity is a measure of how easily water can pass through soil or rock: high values indicate permeable material through which water can pass easily; low values indicate that the material is less permeable.
What reservoir holds the greatest amount of water besides the oceans?
What reservoir holds the greatest amount of water besides the oceans? Atmosphere.
What is specific yield and retention?
Specific retention is that volume fraction of water that is held back by adhesion and capillary forces, when an aquifer is drained. Specific yield is the amount of water that is actually available for groundwater pumping, when sediments or rocks are drained due to lowering of the water table.
How do you calculate specific retention?
The volume retained, VR, is the volume of water in the effective pore space minus the volume drained, (VI – VD). The specific retention can also be computed as the effective porosity minus the specific yield (Sr = ne – Sy).