Question

The annual storage in Broad River watershed is 0 cm/y. Annual precipitation is 100 cm/y and evapotranspiration is 50 cm/y. The sandy loam soil in the watershed has an infiltration rate of 5 × 10-7 cm/s. The area of the watershed is 40 km2. Calculate the annual flow at the outlet of Broad River. What is the runoff coefficient for this watershed?

Answer 1

Answer:

The annual flow at the outlet of Broad River is 13688480 m³

The runoff coefficient for the watershed is 0.342212

Explanation:

Here, we have

The annual storage in  the watershed = 0 cm/y

Annual precipitation = 100 cm/y

Annual evapotranspiration = 50 cm/y

infiltration rate = 5 × 10-7 cm/s

Watershed area = 40 km²

From the question, annual infiltration rate is given by

Annual infiltration rate = 5 × 10-7 cm/s × ‪31557600‬ s/year = 15.7788 cm/y

Therefore, annual flow =

Annual precipitation - Annual evapotranspiration - Annual infiltration rate - Annual storage in  the watershed

Annual flow = 100 cm/y - 50 cm/y  - 15.7788 cm/y - 0 cm/y = 34.2212 cm/y

The area of the watershed = 40 km²

Therefore, the volume of the annual flow is given by;

Height of annual flow × area of the watershed

Volume of annual flow = 34.2212 cm × 40 km²  =  1368.848 cm·km²

= 13688480 m³

The runoff coefficient = $\frac{Amount \hspace{0.1cm} of \hspace{0.1cm}runoff}{Amount \hspace{0.1cm} of \hspace{0.1cm} precipitation \hspace{0.1cm} received}$ =

The amount of precipitation received is given by

100 cm × 40 km² = 4000 cm·km² = 40000000 m³

Runoff coefficient = $\frac{13688480 m^3}{40000000 m^3}$ = 0.342212.

Answer 2

Answer:

0.34232

Explanation:

See attachment