Question

A drainage basin of fourth order covers an area of 40 sq. km. Within the basin, total length of 1st order drainage is 12.5 km, 2nd order drainage is 8.8 km, 3rd order drainage is 4.7 km and 4th order drainage is 4.0 km. The drainage density of the basin is (give answer in two decimal places).

Hint:

Drainage density is the ratio of the total length of streams to the area of the basin, which provides an estimate of the network of streams in the area.

Answer 1

Step 1: Understanding the question.
The drainage density is calculated as the total length of all drainage divided by the area of the basin.
Step 2: Analyzing the solution.
The total length of drainage is the sum of the lengths of the drainage for each order: \[ \text{Total length of drainage} = 12.5 + 8.8 + 4.7 + 4.0 = 30.0 \, \text{km} \] Next, calculate the drainage density: \[ \text{Drainage Density} = \frac{\text{Total length of drainage}}{\text{Area}} = \frac{30.0}{40} = 1.4 \, \text{km/km}^2 \] Step 3: Conclusion.
The correct answer is 1.4 km/km².