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Specific Retention Percentage (in %) tells how much water remains in the rock after it is drained by gravity. It represents the portion of water that is retained against gravitational forces.
The calculator uses the formula:
Where:
Explanation: The formula calculates the water retention capacity by subtracting the drainable water (specific yield) from the total pore space (porosity).
Details: Accurate specific retention calculation is crucial for understanding groundwater storage characteristics, aquifer properties, and water resource management in hydrogeological studies.
Tips: Enter volume percent of porosity and specific yield percentage. Both values must be valid non-negative numbers, and porosity should be greater than or equal to specific yield.
Q1: What is the typical range for specific retention?
A: Specific retention typically ranges from 5% to 30% depending on the soil or rock type, with finer materials having higher retention values.
Q2: How does specific retention differ from specific yield?
A: Specific yield represents drainable water, while specific retention represents water retained against gravity. Together they equal total porosity.
Q3: What factors affect specific retention values?
A: Particle size distribution, soil composition, compaction, and mineral content significantly influence specific retention values.
Q4: Why is specific retention important in groundwater studies?
A: It helps determine the storage capacity of aquifers and influences how much water can be extracted from groundwater resources.
Q5: Can specific retention be measured directly?
A: While it can be measured through laboratory tests, it's often calculated indirectly from porosity and specific yield measurements.