Drainage density

High school (ages 12+)
Geography

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Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/drainage-density

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the formula?Dd = ΣL / Abasin
2. What is the key influences?Lithology, soil permeability, slope steepness, and relief
3. How do we calculate drainage density?We add up the length of all the streams in a basin and divide that by the basin's area. The formula is Dd = total stream length ÷ basin area. The result tells us how dense the network is.
4. Why does the type of soil or rock affect drainage density?If the ground is hard or the soil is dense, water can’t soak in and runs off the surface, making more streams. Soft or porous ground lets water seep in, so fewer streams appear. The rock and soil decide how water moves.

Drainage Basin: A geographical area where all surface water converges to a single point, such as a river mouth or a lake.
Drainage Density: A quantitative measure of the overall stream channel network within a drainage basin, expressed as channel length per unit area.
Ephemeral Stream: A watercourse that flows only during periods of high rainfall or snowmelt, lacking a continuous flow.
Perennial Stream: A stream that has continuous flow in parts of its stream bed all year round during years of normal rainfall.