• Statement (I) is true: Qanats are ancient underground aqueduct systems first engineered in Persia (modern Iran) in the early 1st millennium BCE.
• Statement (II) is false: Qanats do not collect surface rainwater in steeply sloping cliff tunnels. Instead, a Qanat consists of a mother well tapping an alluvial alluvial groundwater aquifer at the base of hills, followed by a gently sloping underground horizontal conduit/tunnel that transports groundwater over long distances by gravity without pumping, punctuated by vertical ventilation shafts.

Gross storage capacities of these reservoirs at Full Reservoir Level (FRL):

• Nagarjunasagar (Krishna River): $\sim 11,560\text{ Mm}^3$
• Ukai (Tapi River): $\sim 7,414\text{ Mm}^3$
• Sriramsagar / Pochampad (Godavari River): $\sim 3,172\text{ Mm}^3$
• Koyna (Koyna River): $\sim 2,797\text{ Mm}^3$
• Idukki (Periyar River): $\sim 1,996\text{ Mm}^3$

Conversion calculation:

• $1\text{ cumec} = 1\text{ m}^3/\text{sec}$
• $1\text{ day} = 24 \times 60 \times 60 = 86,400\text{ seconds}$
• Total volume in $1\text{ cumec-day} = 1 \times 86,400 = 86,400\text{ m}^3$
• Since $1\text{ hectare} = 10,000\text{ m}^2$, $1\text{ ha-m} = 10,000\text{ m}^3$

\[ \text{Volume in ha-m} = \frac{86,400\text{ m}^3}{10,000\text{ m}^3/\text{ha-m}} = 8.64\text{ ha-m} \]

The relationship between Duty ($D$), Delta ($

\Delta$), and Base period ($B$) is given by: \[ D = \frac{8.64 \times B}{\Delta} \]

Where:

• $D$ = Duty in $\text{ha/cumec}$
• $B$ = Base period in days = $90\text{ days}$
• $\Delta$ = Total depth of water in meters = $70\text{ cm} = 0.70\text{ m}$

Substituting the values:

\[ D = \frac{8.64 \times 90}{0.70} = \frac{777.6}{0.70} = 1110.857 \approx 1111\text{ ha/cumec} \]