[mountaintimefrm]

Probably the best documented example of it working is in the Loess Plateau in China. John D Liu has a couple documentaries on it, here is one: https://youtu.be/IDgDWbQtlKI

A good example of a similar project in India, as covered by Andrew Millison: https://youtu.be/jDMnbeW3F8A

Sepp Holzer did a similar project in Portugal: https://www.youtube.com/watch?v=OUryneCjxV4 ...I believe he also did some pretty large projects in the middle east, but I can't find any vids on them at the moment.

Geoff Lawton has done a ton of projects like this, but maybe not at the landscape wide scales like the projects above.

Probably the best book on the basic principles of how to do it - Rainwater Harvesting for Drylands and Beyond by Brad Lancaster. Also the book Water For Every Farm by P.A. Yeomans is pretty good as well, but not as accessible of a read.

TLDR - To keep desert monsoons from flooding areas downstream, dig a landscape wide network of swales and basins to catch, soak and sink the water into the soil. Properly dug, such earthworks recharge aquifers while stopping flooding and erosion.