Floods! Permaculture and regenerative hydrology

120 million swimming pools

I’ll come on to the swimming pools in a bit. Buzz-talk these days is the newly titled ‘regenerative hydrology’; it’s all good stuff. While it’s interesting that people had to come up with a new name, it is great that what Permaculture designers have been doing for decades is getting heard about.

Swales, half-moons (crescents), micro-dams, Keyline and a whole range of techniques that increase soil's capacity to retain humidity have been in our toolbox since the start.

We talk about watering our plants or irrigating a field, both expressions are misleading. They are both a shorthand for ‘increase the humidity in the soil near the plant roots’. Aquatic plants need water, most of the rest need soil humidity. A pile of sand has a low retention capacity, some water molecules will adhere temporarily to the grains but most will drain through. If we start adding in organic matter, biochar and suchlike the retention capacity is increased and more humidity will be trapped for a longer period. Clay powder will initially absorb water and swell, and then any more water will run off. Again, adding organic matter, etc will increase the retention capacity. Compacting a soil by walking on it or driving over it will decrease pore space and water will run off rather than percolating in. Water molecules rise up a soil profile by capillarity, a bare soil will dry much more quickly than one covered with mulch for example.

When it comes to vegetation we’re looking at a range of different effects. Plants move water molecules up their bodies and transpire it through their leaves, they also create shade which reduces evaporation. Trees do this and they also shed bacteria into the air and these act as the nuclei around which atmospheric water vapour condenses or freezes and then falls. This is why people say that ‘trees create rain’. The leeward side of a hedge will tend to be more humid than the windward side.

All over Europe, we find huge tracts of farmland with scarce a tree to be found. These fields go from being plowed bare soil to cropland and then back to bare soil after the harvest. They are walked on and driven over. Ploughing means losing soil organic matter as it is oxidised to CO2. These practices reduce soil retention capacity and increase soil run-off, neither of these are good things.

Permaculture designers design systems that slow run-off, increase infiltration, reduce evaporation, and increase soil organic matter which increases soil retention capacity. These are good things. We see soils as being the main way to ‘stock’ water. Those systems I described at the beginning, swales, etc are used to this end. Then we go on to design and install things like micro dams, reservoirs, ponds, lakes, and cisterns. These are used to store water over the wet seasons to be used during the dry ones. That said the emphasis is always on reducing irrigation needs using the first set of systems before we start thinking about storage systems.

Onto the 120 million swimming pools, they total around 280 cubic kilometres of water. This was the amount of water that went ‘missing’ from central and southern European soils during the 2022 drought. I don’t know if you remember this drought? Here in France, 100 municipalities had to have water transported in, in Italy half the population faced water restrictions. The impact of the drought on agricultural production was pretty severe, sunflower, maize, and soybean yields plummeted by 15 %, which is a lot. You will probably remember all the wildfires that burnt out of control in France, Italy, Slovenia, Romania, Spain, and Portugal. All signs of a fundamental mismanagement of a resource on which all forms of life, as far as we know, depend. It didn’t have to be this way.

2024 has seen crop yields drop in a number of European countries and the UK. Again it’s water that was the problem, too much when fields needed sowing and planting, still too much during the flowering season, and too much when the crops needed harvesting. In England, in 2024 the wheat harvest was down by 22% when compared to the previous year, and oilseed rape was down by a third. The Energy and Climate Intelligence Unit estimates that the harvests were one of the three worst since they started keeping detailed records in 1983, all because of ‘excess rainfall’.

One of the things that isn’t talked about enough is that as air temperature rises the air can hold more water. I°C rise equals around 7 % more humidity in the air. This is one of the reasons that we’ve been saying for the last few decades that rising global temperatures will bring increased numbers of storms of increasing severity.

It’s all a bit silly really because we’ve known how to do things better for decades. It’s frankly surprising how difficult it can be to encourage farmers to plant trees in their fields and move to no-till sylvo-agro-pasturalist systems. Successive governments around the world have been and are guilty of criminal environmental neglect and have failed in their duty of care towards their electors. The current French government uses 2050 as a target date for carbon neutrality and some other stuff. That’s in 25 years, a quarter of a century, far too late. The floods, the wildfires, and the reduction in harvest yields go seemingly unnoticed or are written off as a ‘blip’ or statistical anomaly.

People working as Permaculture designers find themselves in a strange position. We try and encourage people to understand that without food producers we all go hungry. At the same time, we struggle to convince farmers to change their methods. We have shown that it’s possible to restructure farms to make them resilient to flood and climate change. This involves a wide range of techniques that can be classed as holistic landscape management. Farmers have to work together to develop unified approaches to landscape and farm management. It can’t be done piecemeal, it all has to be integrated into a holistic approach.

We are sending into the future a whole lot of problems that our children and their children will struggle to deal with. Forever molecules, nuclear waste, destroyed aquifers, and polluted waters. It’s neither fair nor just, we can do better and we know how.

Water is life as we say, we would do well to remember that.