Given below are two statements, one is labelled as Assertion (A)... | Agrigyan

• Step 1: Cross-Sectional Area of Orifice ($A$):

$$d = 0.07\text{ m} \implies A = \frac{\pi d^2}{4} = \frac{\pi (0.07)^2}{4} \approx 0.0038485\text{ m}^2$$

• Step 2: Difference in Head ($H$) and Velocity ($v$):

$$H = 19.62\text{ cm} = 0.1962\text{ m}$$ $$v = \sqrt{2gH} = \sqrt{2 \times 9.81 \times 0.1962} = \sqrt{19.62 \times 0.1962} = 1.962\text{ m/s}$$

• Step 3: Discharge Rate ($Q$):

$$Q = C_d \cdot A \cdot v \approx 0.61 \times 0.0038485 \times 1.962 \approx 0.0046078\text{ m}^3/\text{s}$$

• Step 4: Total Time in Seconds ($t$):

$$t = 2\text{ h } 46\text{ min } 40\text{ s} = 7200 + 2760 + 40 = 10,000\text{ s}$$

• Step 5: Total Volume in Lakh Litres:

$$\text{Volume} = 0.0046078\text{ m}^3/\text{s} \times 10,000\text{ s} = 46.078\text{ m}^3 = 46,078\text{ Litres}$$ $$\text{Total in Lakh Litres} = \frac{46,078}{100,000} = 0.46078\text{ lakh litres}$$

• Conclusion: Total discharge is 0.46078 lakh litres. (Correct answer: Option 4)

• Seasonal Rainfall Distribution in India (IMD Normals):
• Southwest Monsoon season (June–September): $\approx 887\text{ mm}$ (~75% of annual rainfall)
• Pre-Monsoon / Summer season (March–May): $\approx 131.5\text{ mm}$ (~11.1% of annual rainfall)
• Post-Monsoon / Northeast Monsoon season (October–December): $\approx 123.8\text{ mm}$ (~10.5% of annual rainfall)
• Winter season (January–February): $\approx 40.8\text{ mm}$ (~3.4% of annual rainfall)
• Correct Sequence: Pre-monsoon season ($131.5\text{ mm}$) > Post-Monsoon season ($123.8\text{ mm}$) > Winter season ($40.8\text{ mm}$). (Correct answer: Option 3)

• Current Meter: Standard electro-mechanical instrument (cup-type or propeller-type) used to measure point streamflow velocity in open canals, irrigation channels, and rivers.
• Other Instruments:
• Water meter: Measures cumulative volumetric water flow in closed pipelines.
• Venturimeter: Measures discharge in pressurized pipes using the Bernoulli constriction principle.
• Piezometer: Measures hydrostatic pressure head at a specific depth. (Correct answer: Option 4)