Irrigation Systems

• Groundwater Wells and Drilling Technologies:
• Percussion (cable tool) drilling $\to$ (II): Uses heavy drill bits lifted and dropped repeatedly, exceptionally suited for hard, fractured, consolidated formations (rock/boulders).
• Rotary drilling $\to$ (I): Uses a rotating bit with circulated drilling mud (bentonite), fast and optimal for unconsolidated formations (sands, silts, clays).
• Artesian well $\to$ (IV): Taps a confined aquifer under hydrostatic piezometric pressure higher than the top of the aquifer (or ground surface).
• Perched aquifer $\to$ (III): A local lens of groundwater resting on an impermeable stratum above the regional main water table, behaving as a localized unconfined aquifer.
• Matching Result: (A) - (II), (B) - (I), (C) - (IV), (D) - (III) (Option 3).

Correct option: (3) (A) - (II), (B) - (I), (C) - (IV), (D) - (ttl)

• ISSS Soil Particle Size Classification:
• According to the International Society of Soil Science (ISSS) standards:
• Coarse sand: $2.0\text{ mm}$ to $0.2\text{ mm}$
• Fine sand: $0.2\text{ mm}$ to $0.02\text{ mm}$ ($0.02 - 0.2\text{ mm}$)
• Silt: $0.02\text{ mm}$ to $0.002\text{ mm}$
• Clay: $\lt 0.002\text{ mm}$
• USDA Comparison: USDA classifies very fine sand as $0.1 - 0.05\text{ mm}$ and silt as $0.05 - 0.002\text{ mm}$.
• Conclusion: Fine sand diameter ranges from 0.02 to 0.2 mm (Option 2).

Correct option: (2) 0.02 to 0.2mm

Matching the items of List I with List II for Vertical drainage:

The correct combination is Option 4: (A) - (Il), (B) - (III), (C) - (1), (D) - (IV)..

Correct option: (4) (A) - (Il), (B) - (III), (C) - (1), (D) - (IV).