The correct relation between the highest rainfall $P_0$, average rainfall depth $P$, and area $A$ (in km\textsuperscript{2}) is:
\[P = P_0 \exp(-K A^n)\]
Here:
$P_0$ is the highest rainfall (in cm),
$P$ is the average rainfall depth (in cm),
$A$ is the area of the region (in km\textsuperscript{2}),
$K$ and $n$ are storm constants that depend on the characteristics of the storm.
Final Answer: $P = P_0 \exp(-K A^n)$ (Option 1)
A watershed has an area of 74 km\(^2\). The stream network within this watershed consists of three different stream orders. The stream lengths in each order are as follows: Ist order streams: 3 km, 2.5 km, 4 km, 3 km, 2 km, 5 km
IInd order streams: 10 km, 15 km, 7 km
IIIrd order streams: 30 km
The drainage density of the watershed is _________km/km\(^2\) (Round off to two decimal places)