1. **State the problem:** We need to estimate the Curve Numbers (CN I, CN II, CN III) for a catchment area with given land use percentages and soil groups B and C. 2. **Understand the data:** The land use and soil group percentages are: - Cultivated land (Paddy): 30% B, 45% C, total 75% - Scrub Forest: 6% B, 4% C, total 10% - Waste land: 9% B, 6% C, total 15% 3. **Refer to Table 1 for CN II values:** - Cultivated land (Paddy) CN II = 95 (for all soil groups) - Scrub Forest CN II: 47 for B, 64 for C - Waste land CN II: 80 for B, 85 for C 4. **Calculate weighted CN II for each land use:** For each land use, calculate weighted CN II by soil group percentage: $$\text{Weighted CN II} = \frac{(\text{CN}_B \times \%B) + (\text{CN}_C \times \%C)}{\%\text{total area}}$$ - Cultivated land (Paddy): $$\frac{(95 \times 30) + (95 \times 45)}{75} = \frac{2850 + 4275}{75} = \frac{7125}{75} = 95$$ - Scrub Forest: $$\frac{(47 \times 6) + (64 \times 4)}{10} = \frac{282 + 256}{10} = \frac{538}{10} = 53.8$$ - Waste land: $$\frac{(80 \times 9) + (85 \times 6)}{15} = \frac{720 + 510}{15} = \frac{1230}{15} = 82$$ 5. **Calculate overall CN II for the catchment:** Weighted average by total area: $$\text{CN II}_{\text{catchment}} = \frac{(95 \times 75) + (53.8 \times 10) + (82 \times 15)}{100}$$ $$= \frac{7125 + 538 + 1230}{100} = \frac{8893}{100} = 88.93$$ 6. **Estimate CN I and CN III:** CN I and CN III are typically estimated by adjusting CN II by ±5: - CN I = CN II - 5 = 88.93 - 5 = 83.93 - CN III = CN II + 5 = 88.93 + 5 = 93.93 **Final answers:** - CN I ≈ 83.9 - CN II ≈ 88.9 - CN III ≈ 93.9 These values represent the curve numbers for the catchment based on the given land use and soil groups.