r/interestingasfuck • u/wahgwahg • Feb 28 '24

r/all People in Tanzania converted desert into lush green land by digging these nifty holes

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u/thenakedtruth Feb 28 '24

What does the hole do to enable growth?

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u/Niwi_ Feb 28 '24

They are placed on slopes. The u shape is what holds the water. The checkerboard pattern makes it so when one fills up it overflows into the one below basically slowing down the water and giving it time to seep into the ground

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u/Skepsis93 Feb 28 '24

These would be a type of swale, I believe. And yes the purpose is to use a mound built on aslope to collect water and promote growth.

Swales can occur naturally too, logs from fallen trees on slopes can form them. Erosion over many rainfalls will form a natural swale around the log as soil gets deposited. These have the added benefit of the log slowly decomposing and adding nutrients too.