How should data from a river transect be presented to show changes downstream?

• A. A histogram of river depth categories.
• B. A pie chart of river features.
• C. A line graph along transect with distance downstream.
• D. A scatter plot of unrelated data.

Answer: (C)

When you want to show how a river’s measurements change as you move downstream, plot the variable against distance downstream on a line graph. This keeps the order of sampling along the transect and makes trends, gradients, and any sudden changes easy to see as you travel downstream. A line graph also lets you compare data from different transects or variables by adding more lines.

Histograms summarize how often values fall into depth categories, which hides where along the river those values occur. Pie charts show proportions at one point in time and don’t reveal a sequence along the river. A scatter plot of unrelated data wouldn’t clearly convey how the variable changes with distance, whereas a line graph directly shows the progression along the transect.