वियर (Weir) के निर्माण और स्थापना के संबंध में निम्नलिखित में से... | Agrigyan

NRCS (USDA-SCS) Hydrologic Soil Groups classification:
Group A: Deep sand or gravel; very high infiltration rate ($\gt 0.75\text{ cm/h}$); low runoff potential (Statement A is false, B is true).
Group B: Moderately deep to deep, moderately fine to moderately coarse textures (loam/silt loam); moderate infiltration rate ($0.38 - 0.75\text{ cm/h}$); moderately low runoff potential (Statement D is false).
Group C: Soils with impeding layer or moderately fine/fine texture (clay loams); slow/low infiltration rate ($0.13 - 0.38\text{ cm/h}$); moderately high runoff potential (Statement C is true).
Group D: Heavy clays with high swelling, high water table, or shallow over impervious layer; very low infiltration rate ($\lt 0.13\text{ cm/h}$); high runoff potential (Statement E is false).

Standard rules for sharp-crested weir installation for accurate discharge measurement:
Statement (C) is true: The head over the weir (\(H\)) must be measured at an upstream distance of at least \(4H\) to \(5H\) (typically 4 times maximum head) to avoid the drawdown (surface curve) effect immediately preceding the crest.
Statement (A) is false: The approach velocity must be kept low ($\lt 0.15\text{ m/s}$) or explicitly accounted for in discharge calculations.
Statement (B) is false: The height of the crest above the channel bottom must be at least \(2H\) to \(3H\) (NOT closer than \(2H\)) to prevent contraction suppression.
Statement (D) is false: Free flow with adequate nappe aeration underneath is mandatory to prevent suction and measurement errors.