We have a catchment with a total area of 9.0 km2, where the runtime principle applies. The area is subdivided in 5 regions (A1 to A5) in such a way that every individual area has a runtime of 30 minutes. The areas drain sequentially. A5 is at the top of the catchment and A1 at the bottom of the catchment near the outlet.

Question

We have a catchment with a total area of 9.0 km2, where the runtime principle applies. The area is subdivided in 5 regions (A1 to A5) in such a way that every individual area has a runtime of 30 minutes. The areas drain sequentially. A5 is at the top of the catchment and A1 at the bottom of the catchment near the outlet.

A1 A2 A3 A4 A5
Area (km2) 1.5 2.4 2.4 1.5 1.2
We assume that the rain falls uniformly over the catchment, and that the discharge starts immediately after the start of the rain. The discharge only occurs as a result of the net (i.e. effective) rain.

QUESTION 1 (1 point possible)
Assume rain with a net intensity of 4.5 mm/hr, that lasts (in theory) infinitely long. What will eventually be the discharge in [m³/s] at the outlet of the catchment? If applicable, round your answer to two decimals.

Enter the the discharge in [m³/s] :

Answer 1

To calculate the discharge at the outlet of the catchment, we can use the runoff coefficient method. The runoff coefficient is a dimensionless parameter that represents the portion of rainfall that becomes runoff.

First, we need to determine the total effective rainfall for the catchment. The effective rainfall is the portion of rainfall that contributes to runoff. We can calculate it by multiplying the net rainfall intensity (4.5 mm/hr) by the duration of the rainfall. In this case, since the rain lasts infinitely long, the total effective rainfall will also be infinite.

Next, we need to calculate the total runoff volume for each area. The runoff volume can be determined by multiplying the effective rainfall for each area by its respective area. Since the runtime principle applies, the effective rainfall is the same for all areas and equals the total effective rainfall divided by the number of areas (5).

Lastly, we can calculate the discharge at the outlet by summing up the runoff volumes for each area and dividing by the duration of the rainfall. Since the duration is infinite, the discharge will also be infinite.

Therefore, the discharge at the outlet of the catchment is infinite.

11.25

To calculate the discharge at the outlet of the catchment, we can use the runoff coefficient method. The runoff coefficient is a dimensionless parameter that represents the portion of rainfall that becomes runoff.