A rainfall hyetograph is a graphical representation that shows
- AThe cumulative rainfall over time
- BThe intensity of rainfall over a time intervalCorrect
- CThe relationship between rainfall depth and area
- DThe probability distribution of rainfall events
Solution
Concept
Definition and graphical characteristics of a rainfall hyetograph
Formula
NONE
Step-by-step solution
1. A rainfall hyetograph is a graphical plot displaying rainfall intensity (e.g., mm/hr) or interval rainfall depth versus time. 2. It is typically drawn as a bar chart (step graph) representing discrete time increments of a storm. 3. The area under the hyetograph represents total rainfall depth over the storm event. 4. Therefore, option B accurately describes a hyetograph. Answer: B
Explanation
A rainfall hyetograph is a bar graph showing rainfall intensity (or rainfall depth per unit time, such as mm/hr) plotted chronologically on the vertical axis against elapsed storm time on the horizontal axis. In contrast, cumulative rainfall depth plotted against time represents a rainfall mass curve.
Why the other options are wrong
A) Cumulative rainfall over time is depicted by a rainfall mass curve, not a hyetograph. C) The relationship between rainfall depth and area is shown by Depth-Area-Duration (DAD) curves. D) Probability distribution of rainfall is represented by intensity-duration-frequency (IDF) curves.
Shortcut
Hyetograph = Rainfall Intensity vs Time (bar graph); Mass Curve = Cumulative rainfall depth vs Time.
Common mistake
Confusing a hyetograph with a rainfall mass curve (which plots cumulative rainfall over time).
Correct answer: B) The intensity of rainfall over a time interval