Global Warming: Solutions to Droughts, Fires, and Floods
How restoring the water cycle can protect forests and people (Part 1)
Alpha Lo is a water physicist who educates the public and organizes coalitions to restore the water cycle and rehydrate the landscape using natural processes. He co-founded the Regenerative Water Alliance and publishes the newsletter, Climate Water Project, on Substack.
A cycle of drought, fire and floods—exacerbated by human induced climate change—is entangling the earth.
California, British Columbia, Australia, Greece, and Brazil are examples of places that have recently been hit by all three of these natural disasters that are interlinked in ways not always noticed:
Fires can lead to floods. When fires get too hot they can form a waxy coating on the soil that prevents the landscape from absorbing water from huge rain storms. Instead, the stormwater gathers speed as it flows downhill to inundate urban areas with floodwaters. In 2020, wildfires unfurled across the Australian landscape and degraded the soil. Two years later the soil was unable to absorb all of the stormwater, causing massive floods that affected millions of people.
Floods can lead to wildfires. Floods can wash away topsoil and create landslides. In the future, less water is absorbed by the landscape during rainstorms so less water sinks into the aquifers below. Less groundwater infiltration means less water to keep the rivers flowing and the soil and vegetation moist into the dry season, thus increasing the chances of wildfires.
Fires can lead to droughts. Deforestation by fire (or logging) limits evapotranspiration (absorption of plant moisture by the air), disrupting the water cycle that brings rain to replenish rivers, aquifers, soils, plants, wildlife and human life. Forests act as conveyor belts to bring moisture inland. Without a chain of forests going inland, rainfall decreases exponentially the further inland one goes. With a chain of forests the rainfall remains consistent going inland. Two Russian physicists, Anastassia Makarieva and Victor Gorshov, have mapped out this pattern of rainfall [1] called moisture hopping in the climate-science literature. Climate scientist Francina Dominguez did computer simulations of moisture hopping in the US, and found that the 2012 drought in the Midwest was cause partly by the drought in California because not enough water vapor was being passed inland. Moisture from California accounted for 15% of the rains in the Midwest.[2] Climate scientist Antonio Nobre has shown how the burning of the forests in the Amazon causes droughts in other parts of South America.[3] Meteorologist Millan Millan showed how paving over nature in Spain led to less rain there. [4,5] Through evapotranspiration nature normally combines inland moisture with the ocean moisture to create rain, but urbanization (another form of deforestation) also decreases evapotranspiration and helps cause droughts. [6] In the 2020 California wildfires, two million hectares of forest was lost, and 20% of old growth trees, weakening the rain conveyor belt, which will lead to more droughts further inland in the future.
So what can we do about this cycle of disasters?
Enhancing the ability of landscapes to retain rainwater is a solution which addresses all of the types of disasters.
If landscapes can retain more water they will be more hydrated in the dry season, which which means fewer wildfires. And, if landscapes located uphill can absorb more water when it rains, the volume and velocity of floods will be less at lower elevations.
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There are many ways to retain more water in the landscape.
Increasing soil sponginess, for example, can decrease flood strength by 20% [7]. Each one-percent increase in organic matter in the soil increases its ability to hold water by 20,000 gallons per acre.
Many methods exist to increase organic matter in soil. Inoculation of the soil with mycelium which helps to break down biomass to form organic matter. The fields of permaculture and regenerative agriculture provide a compendium of methods to improve the ‘soil carbon sponge’.
Another way to retain more water in the landscape is to use a variety of earthworks like berms, swales (digs dug into the ground), terraces, check dams, and water pianos [8] that slow or catch the water, after which it usually sinks at a much slower rate allowing it to seep out into rivers and landscapers into the dry season. And plants can use capillary action to draw up water that flows underground to create shallow water tables.
A third way to retain more water in the landscape is to restore wetlands in the floodplains and the rivers that feed them. Wetlands and their vegetation can absorb a lot of floodwaters. [9,10,11] One acre of wetland can hold one million gallons of water during floods. Wetlands can release water slowly, hydrating the landscape more during dry seasons.
Wetlands can also replenish aquifers, increase humidity, and lower temperatures.[12,13] This leads to cooler winds that are less likely to fan wildfires. Wetlands are also natural firebreaks.
If we restored our rivers and removed the flood control levees and their concrete banks water could flow onto the floodplains and fill the wetlands during heavy rains.
The ability of the landscape to absorb floodwaters is important.
California gets half of its water from atmospheric rivers of water vapor coming from the ocean that empty themselves on the land. If that water is not absorbed the drought situation in California becomes worse.
Dams are not the best way to absorb atmospheric river-water. They have to release a lot of that water after big storms in order to maintain a buffer for water from future storms. Dams also also problematic because they remove soil and sediment from the ecosystem.
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Wetlands and aquifers are better water storage solutions. Wetlands guide the water into aquifers that have much larger storage ability than dams. Farms and cities can draw from that water.
So we want to transition from a water infrastructure that is heavily dependent on dams to more of a dam-wetland hybrid—a transition to nature based solutions is both more efficacious and financially wise. [9]