Regenerate mulch as needed with leaf drop and cut-up prunings from the plants growing in the basin. The rate of decomposition of the biomass in the basins will be quicker than non-basin areas due to the increased water inputs, which leads to a nice balance. I’ve found that by the time plants are ready for another pruning, the basins are ready for another application of mulch from cut-up prunings.

Key Elevation Relationships for Backwater or Eddy Basins
The upper edge of the farthest-downstream section of the basin (A) must be higher (ideally at least 4 inches [10 cm] higher) than the basin’s curb-cut, or curb-core, inlet (B)(fig. 1).

If the upper edge of this downstream section of the basin (A) is lower than the inlet (B), the basin will act as a flow-through basin, not a backwater basin, as water will overflow at the downstream end (taking mulch with it) and, in this context, erode the earthen walkway. Thus, steeper streets will have shorter eddy basins (parallel with the street), while more-gradually sloping streets can have longer eddy basins.

Figure 2. Water-harvesting eddy basins created by Eden on Earth on a curbless street in Clarkdale, Arizona.
Before the work, road runoff would flow up against and flood the house. After the work, the dirt dug from the street-side basins created a raised walkway that acts as a berm ensuring no basin water or street runoff can flow up against the house.
Before the work, there was no walkway; now there is a wonderful path wide enough for two people to walk side by side, separated by the trees from cars and street. Now the trees have grown to shade both walkway and street.
Photo taken by Carol Luhman just after the work was completed in 2007.



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