- 2078 Bhadra · 8 marks
Balancing reservoir, 3 million city, 10 hours pumping
Short answer
Using the analytical mass-curve method with pumping 10 h/day and daily demand 330,000 m³, cumulative surplus peaks at 82,500 m³ and no deficit occurs. Balancing reservoir capacity = 82,500 m³, or 25% of daily demand.
Determine the storage capacity of balancing reservoir by analytical method for 10 hours pumping (5 am to 10 am and 2 pm to 7 pm) and continuous water supply. The population of a city is 3 million has a water demand of 110 lpcd. The consumption pattern as follows:
| Time | 5-10 | 10-14 | 14-19 | 19-22 | 22-5 |
|---|---|---|---|---|---|
| Consumption | 35 | 15 | 25 | 15 | 10 |
Given data
- Population 3,000,000 × 110 lpcd = 330,000 m³/day
- Pumping 10 h/day (5–10 h and 14–19 h), at a constant rate of 330,000/10 = 33,000 m³/h
- Supply from the tank to the city is continuous, with the % consumption given
Mass-curve table (analytical method)
Inflow: 33,000 m³/h during 5–10 h and 14–19 h only (pumped). Time is counted from the start of the first demand period; a positive cumulative value means surplus in the tank.
| Time | Demand (m³) | Inflow (m³) | Inflow − demand | Cumulative |
|---|---|---|---|---|
| 05:00–10:00 | 115500.00 | 165000.00 | +49500.00 | +49500.00 |
| 10:00–14:00 | 49500.00 | 0.00 | -49500.00 | 0.00 |
| 14:00–19:00 | 82500.00 | 165000.00 | +82500.00 | +82500.00 |
| 19:00–22:00 | 49500.00 | 0.00 | -49500.00 | +33000.00 |
| 22:00–05:00 | 33000.00 | 0.00 | -33000.00 | 0.00 |
Total demand = 330000.00 m³; total inflow = 330000.00 m³.
Capacity
- Maximum cumulative surplus = 82500.00 m³
- Maximum cumulative deficit = 0.00 m³
- Balancing capacity = max. surplus + max. deficit = 82500.00 + 0.00 = 82500.00 m³
Answer: Balancing reservoir capacity = 82,500 m³ (25% of the daily demand).
✓ Answer checked by Claude Opus 5.5 (high effort)
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