Biopore Flood Prevention

It’s fall up in those temperate climates nowadays. So if you have a yard and or garden, as you sweep up those leaves, and especially if you live in an area with drainage problems, think about this post.

Flooding is a big problem in this region during the rainy season. I’ve seen a few heavy rains that sent water tearing through the streets and Claudia scoffed at their insubstantiality. Really though, it doesn’t take much for the water to stay above ground level.

The earth in Ocotal is made from clay, rich in nutrients, but rife with drainage issues. Once upon a time there were great pine forests here (in fact, the name “Ocotal” is from the indigenous word for a pine tree). The trees’ roots penetrated the clay and allowed for the water to drain and enter into the groundwater. When the forests were cleared the earth compacted.

Claudia’s stories of previous winters evoked Gabriela Garcia Marquez’ tellings of cooking the crabs that crawled along the floors in the Colombian rainy season, except, there’s less crabs here and so it sounded less fun. A little nervous about a couple months of wet feet, I started doing research into flood prevention and ground water reparation. There is a lot out there about permaculture landscaping with retention ponds and recreating pond habitat, but, sadly, there will be no ponds or streams in this yard, if not for the threat of dengue then for the lack of space.

Then I came across this technique they’re implementing in Jakarta to deal with monsoons. To summarize, it’s basically a deep narrow hole in the ground filled with organic waste. The composting organic material attracts things like worms and insects that aerate the soil and make the earth more absorbent.

breaking ground bar

breaking the earth with the barra

I dug two about a month ago (about 1m deep X 18cm) wide and filled them with the leaves from pruning our mango trees. The last time it rained I was pleasantly surprised (honestly, I had my doubts) to see that in about a 7 foot radius of the holes there wasn’t any standing water after the storm.

I don’t understand why the original design implements cement, it seems unnecessary from what I’ve done so far, but maybe it’s because Indonesian ground is looser? It seems like the compost itself does a fine job of sustaining the walls. Anyway, I have modified their design by getting rid of the concrete and making the hole ever so slightly wider thanks to lack of a post-hole digger.

pouring plant in a hole

pouring a chopped up banana tree in the hole

The idea seems sound to me. The holes both improve rain water penetration and provide for an extremely low maintenance compost pit that re-integrates the nutrients form organic waste into the soil that grew them.

Last weekend I added another hole, and there will be another this week. All it takes is a little digging. I find I can do one in about 3 hours, and it would be faster if the ground weren’t so tough. It’s just a matter of alternating between using the barra and a shovel and scooping.

finished biopore

Finished biopore. Hm, it looks like I just spent 3 hours doing nothing.

Then I throw in whatever I can get my hands on. This recent hole had a chopped up banana tree, some rotting fruta de pan, and a bunch of mango leaves.

To add to the rewards, around here at about a meter’s depth one finds real clay, though not the high quality red stuff they have in Mozonte. This last time I showed Claudia’s daughter Nicolle how to get the grit out by soaking it in water.

home-made clay

Nicolle made a cake

home made clay head

I made a head. In your face Nicolle.

It was the mango leaves that made me think that this is something that might be useful back in the temperate Northern lands too. Right now everyone with a yard has a pile of leaves that will probably be hauled away in Yard Waste trucks. It’s easy to forget that when they haul away those leaves, they’re hauling away topsoil and all the good nutrients in the earth that it took to grow them that could be going into the growth of food. Why would anyone just give that away?

Interesting note: Its actually not an entirely new concept. To my surprise, I came across a passage the other night in Steinbeck’s East of Eden, set at the beginning of the 20th century, talking about a plot of land on hard clayey earth. One character said something to the effect of, “if we could just dig enough holes into it, maybe some water would get in there.”