Hydrology

Potamology is the branch of science that deals specifically with the study of surface streams, such as rivers and streams. It focuses on their physical, chemical, and biological characteristics.

The infiltration rate ( ) is calculated using:

where:
Total rainfall intensity,
(converted to mm/hr: 72 mm/hr).
Rainfall intensity over 6 hours:

Runoff converted to mm/hr:

Infiltration rate:

Average infiltration rate:

The pan coefficient ( ) is used to convert evaporation measured from a pan to the equivalent evaporation over a larger water body. For the United States Weather Bureau Class A pan, the average pan coefficient is approximately 0.70, accounting for the differences in heat storage and energy exchange between the pan and a natural water body.

The correct relation between the highest rainfall , average rainfall depth , and area (in km\textsuperscript{2}) is:

Here:
is the highest rainfall (in cm),
is the average rainfall depth (in cm),
is the area of the region (in km\textsuperscript{2}),
and are storm constants that depend on the characteristics of the storm.
Final Answer: (Option 1)

The average rainfall ( ) is calculated using the Thiessen polygon method:

where:
: Thiessen weights of gauges,
: Rainfall values at gauges A, B, C, and D.
Given:

Simplify:


Solve for :


Thus, the rainfall at A is .

The form factor ( ) of a drainage basin is calculated using the formula:

where:
(area of the basin),
(length of the main stream).
Substitute the values: