Don't know if you have seen these, Rad.
Desert Swales built in 1937 in Sonoran Desert
- created an area of lush green plants and trees
- self- seeded and not irrigated (purely rainfall and earthworks)
- note the swale banks are very high and wide. Swales can be seen on Google Earth
- Sonoran Desert can get between 3" - 15" rain per year.
Flat Land swale
- on flat land with a 2.25 % grade (3 1/2 inch drop)
- swale captured 12,000 gallons of water (45,000 litres) from a 1-inch rain event
-this includes catchment from rooftop and road
Al Baydha Project in Saudi Arabian Desert
-land gets 3"- 3 1/2 " of water per year
-Temperatures of 100 degrees, evaporation currently at 15% (will go down as trees and plants grow over time).
- Al Baydha project land got no rain for 3 years. Installed earthworks in the meantime.
When rain fell the earthworks captured 13.5 million litres of rainwater.
Water comes off the mountain nearby, which you don't have.
But berm is interesting -reminds me of the swale banks in video of Sonoran Desert, which is mostly flat.
Neal Spackman. This video is also on this forum, elsewhere.
Building a berm
Underground storage of water; stepwells and rooftop catchment — Ancient water harvesting technology
- in Golden Desert in India where much of ground water is saline, can't use wells
3 cm-16 cm of rain per year