HOW DO YOU INCREASE (OR DECREASE) FLOODING? BY DECREASING (OR INCREASING) THE AMOUNT OF WATER THAT SOAKS INTO THE GROUND.
Why was the American Southwest wetter during the Pleistocene era? Because it had more animals. We can replace the lost animals with properly managed livestock.
From an interview with Ricardo Aguirre, who is a civil engineer, with a focus on flood control. Ricardo has trained himself in Holistic Land Management, so as to decrease runoff and thereby decrease flooding, while restoring local ecosystems and turning (man-made) deserts into restored grassland ecosystems.
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Note: In this part of the interview, I meant to ask Ricardo how to DECREASE runoff, and thereby decrease flooding. Instead, I asked how to INCREASE runoff. Ricardo took my question, as posed, and ran with it.
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HART HAGAN: What can you do to increase the amount of water that runs off during a rain event?
RICARDO AGUIRRE: Well, to increase the amount of water to run off during rain events, you can do what we've already been doing, which is to increase desertification, which is something I don't think we really want to do. We probably want to prevent that from happening. Through desertification, we're actually increasing flooding and causing more soil loss, more dust storms and more wildfires.
So what you can do is, you could remove soil organic matter. We’ve done a really good job of that by removing livestock from the land. On second thought, let's not say livestock, but megafauna (large animals, mainly wild animals). But we can use the livestock as a surrogate for the wild animals that are now absent from the land.
We were communicating with an official recently. And I told her that we're looking to mimic the Pleistocene era. She responded by saying the Pleistocene era was different because it was much wetter during that time.
I didn't really want to respond to her directly, but she's making my point for me. There's a reason the Pleistocene was wetter, because we had functioning watersheds.
So yeah, it's changed. We’re not in that era anymore. We have largely man-made deserts that formerly were grasslands. So we have changed that wet condition of the pleistocene era.
So, to increase runoff (flooding) what you do is you remove megafauna or large ungulates or ruminants from the land. You thereby break the mineral cycle. When you break the mineral cycle, you break the water cycle and you get more runoff and more flooding.
So, basically, we're proposing to do the opposite and we're demonstrating practices to get livestock mimicking those former grazing animals to demonstrate that we can get the mineral cycle repaired and then the water cycle repaired concurrently and catch water where it falls.
HART HAGAN: How can grazing livestock have a positive impact on the land?
RICARDO AGUIRRE: The specific outcome is that you've got the hoof action of medium to large ruminants in the form of cattle and sheep, and that disturbs--breaks up--the crusting of the bare soil. It can even break up compaction. What we're doing is mimicking a form of predator-prey relationship that had coexisted with perennial grasses for many thousands of years.
And we're showing that when the livestock break up the soil capping, and we create these small depressions where they step, it's an opportunity for rain to fall and be caught there and to penetrate into the ground and then to germinate seeds and for seeds to grow.
Then in time--hopefully it's not so completely bare that it’s a moonscape--they also are trampling plant matter into the ground. They are dunging and urinating. And you've got the biology in their rumen. The cattle have six stomachs. Sheep have two. There's a lot of biology in their stomachs, and when you concentrate that in a high stock density situation, and when you distribute that dung and urine and trampling evenly, along with the grazing, then you're mimicking what the keystone predators have done in the past with former grazing animals.
(Note: When predators stalk grazing animals, they keep the animals bunched up and moving, so that they create a substantial impact for a short duration, and then move on, thus evenly distributing the grazing, the hoofprints, the dung and the urine.)
High stock density mimics these patterns. We are getting that mineral cycle working again and creating a sponge for water to get caught where it falls.
(Mineral cycles include the carbon cycle, the nitrogen cycle, the phosphorus and potassium cycles and myriad others. Every nutrient must move around in a biologically driven cycle in order to be optimally distributed to the plants, animals, fungi, microbes and living systems that need them to thrive.)
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To listen to the entire interview with Ricardo Aguirre, please click on the link.