Plotting recurrence interval vs. annual rainfall on log-log paper facilitates estimating rainfall magnitudes for specific recurrence intervals, such as 50 and 100 years, through suitable interpolation methods.
To plot the curve of recurrence interval vs. annual rainfall magnitude, and subsequently estimate rainfall magnitudes for specific recurrence intervals, you can follow these steps:
Plotting the Curve:
Use a log-log paper to represent recurrence intervals on the x-axis and annual rainfall magnitudes on the y-axis.
Plot the data points from the 25 years of annual rainfall records.
Fit a best-fit line or curve through the data points, representing the relationship between recurrence intervals and rainfall magnitudes.
Interpolation for 50-Year Recurrence Interval:
Locate the point corresponding to a 50-year recurrence interval on the x-axis.
Draw a vertical line from this point to intersect the curve.
From the intersection point, draw a horizontal line to the y-axis to determine the estimated rainfall magnitude for a 50-year recurrence interval.
Interpolation for 100-Year Recurrence Interval:
Similarly, locate the point corresponding to a 100-year recurrence interval on the x-axis.
Draw a vertical line from this point to intersect the curve.
Draw a horizontal line from the intersection point to the y-axis to estimate the rainfall magnitude for a 100-year recurrence interval.
This process allows you to visually interpret the recurrence interval vs. rainfall magnitude relationship and estimate values for specific recurrence intervals through interpolation on the log-log plot.