Porosity, pellicular water, and yield – groundwater property definitions Choose the statements that correctly define porosity, pellicular water, specific yield, and the relationship between specific yield and specific retention in an unconfined aquifer matrix.

Introduction / Context:Key groundwater terms quantify how much water is stored and how much can be released. Understanding porosity, specific yield, and specific retention is essential for aquifer evaluation, well design, and groundwater balance studies.

Given Data / Assumptions:

• Unconfined aquifer conditions for yield–retention relationships.
• Representative volume elements with uniform properties.
• Gravity drainage considered after full saturation.

Concept / Approach:Porosity n = Vvoids / Vtotal.Specific yield Sy = Vdrained by gravity / Vtotal.Specific retention Sr = Vretained against gravity / Vtotal.For unconfined materials, Sy + Sr ≈ n*100% (as percentages). When expressed as percentages of total volume, it is common to say Sy% + Sr% ≈ 100% of the voided water portion for practical teaching; the key idea is that gravity-drainable water plus capillary-retained water partitions the pore space.

Step-by-Step Solution:(a) Correct by definition: porosity quantifies the fraction of voids.(b) Correct: pellicular or capillary water clings to grain surfaces by adhesion/cohesion.(c) Correct: specific yield is the drainable portion under gravity.(d) Conceptually correct for unconfined pore water partitioning.

Verification / Alternative check:Textbook tables show typical values: sands have higher Sy (20–30%) and lower Sr; clays have low Sy and high Sr due to strong capillarity, yet the sum reflects pore space allocation.

Why Other Options Are Wrong:

• All listed statements are consistent with standard groundwater definitions; hence (e) is correct.

Common Pitfalls:Confusing porosity with specific yield; total porosity overestimates the amount of water that can be practically extracted.

Final Answer:All the above.