What is a good river? And what is a river good for?
Most people will imagine a good river as a blue ribbon flowing through a beautiful city, the Seine in Paris or the Danube in Budapest. And most will think that rivers are good for providing clean and clear water for people to drink.
These good rivers have well-defined boundaries that we expect them to stay within, just as we draw blue lines on a map to define rivers as stationary and ordered.
In short, we expect rivers to be well behaved, predictable sources of clean water that stay between the lines.
But what if many of the fundamental benefits of rivers are possible only when they don’t stay between the lines? And what if those benefits require muddy, not clean, water?
What are the benefits of misbehaving rivers of muddy water?
For one, look at the food on your plate. What we eat comes from diverse food systems, from local to global, all underpinned by agriculture. The first seeds for agriculture were quite literally planted thousands of years ago in the soil left behind by a muddy river that didn’t stay between the lines.
This is the eighth in a series about how rivers are crucial for feeding the world. Previous posts have examined irrigation, freshwater fisheries, and deltas.
This post will focus on a form of food production known as “flood recession agriculture.” It is the original form of agriculture and remains important to this day, particularly in rural areas of Asia and Africa.
From 8th grade world history, you can probably remember the list of places where civilizations first emerged, including the Nile, the Indus, the Yangtze and the Ganges. What do those places all have in common? They are all the names of rivers.
What about perhaps the oldest civilization of all – Mesopotamia? That’s not a river you say. Well, the word ‘Mesopotamia’ is from ancient Greek and it means “the land between two rivers” – the Tigris and Euphrates.
These civilizations all emerged in river valleys. A valley is defined as a broad, flat area next to a river. But a valley isn’t just next to a river; it was made by the river. The reason a valley is broad and flat is that it has been built up over millennia by dozens or hundreds of floods. Floodwaters tend to look brown and muddy because they have the energy to carry sediment (silt, sand and clay), but when they spread out away from the river during the flood, the floodwaters slow and they drop that sediment. So, valleys are built over time with each flood laying down a new layer of highly fertile soil.
Civilizations tended to emerge in river valleys because that is where agriculture emerged. And agriculture emerged in valleys because river floods did so much of the work necessary for agriculture to succeed.
Think about all of the work that underpins successful agriculture: preparing soil, clearing weeds, spreading fertilizers, controlling pests, and delivering water.
In a river valley, floods can do each of those steps. As a flood recedes, it leaves behind a layer of freshly deposited soil (soil preparation) that is high in nutrients (fertilizer). Floods either remove existing vegetation and/or bury it in sediment (weed clearing) and floods can even kill or drive away rodents and terrestrial insects (pest control). The freshly deposited soil has a high water content and the water table, maintained by the adjacent river level, remains shallow and accessible to growing roots (water delivery).
All that is left is to plant the seeds.
Within those river valleys thousands of years ago, people began experimenting with agriculture by spreading seeds of preferred plants in the fresh soil left behind by floods. Because the river, through its floods of muddy water, had created such favorable conditions for plant growth, these were optimal places for early experiments with cultivation, and these are the places where people learned the ropes for more structured agriculture that would eventually spread around the planet.
This origin story of cultivation is still repeated today through flood recession agriculture. This type of farming remains an important form of agriculture in many regions, primarily in Africa and parts of Asia, where it is practiced on about 25 million acres, about the same amount of cropland as found in Italy.
Flood recession agriculture can be particularly important in arid regions, where riverside fields may be the only option for growing crops (see images below of crops growing after a flood in an arid region of Senegal).
Flood recession agriculture remains important in many rural regions because it requires very little capital or equipment and so is accessible to anyone with access to riverside land. Villages that practice flood recession agriculture also usually engage in fishing and graze livestock in grasslands that are also nurtured by floods.
The Barotse floodplain on the upper Zambezi (Zambia) provides an example of a floodplain providing multiple values and being central to livelihoods and culture. Communities of the Barotse derive diverse livelihoods from the floodplain, including livestock rearing, crop production, and fishing. It is also a popular tourist destination with its annual festival celebrating the relocation of the king and the Lozi people to higher ground before the onset of the flood season. The Kuomboka Festival (literally, the “moving out of the water”) celebrates the benefits of annual flooding in song and poem.
The Lozi poem below reveals a dramatically different view of floods than is typical in most of the world.
A flood poem of the Lozi people from the Barotse Floodplain in Zambia.
It is flood time in Bulozi.
The floodplain is clothed in the water garment.
Everywhere there is water! There is brightness! There are sparkles!
Waves marry with the sun’s glory.
Birds fly over the floods slowly; they are drunken with cool air.
They watch a scene which comes but once a year.
Floods are beautiful.
(excerpted from a traditional song translated by O. Sibetta)
This is clearly a poem about a “good flood,” about a river that delivers a flood of benefits. In subsequent posts I’ll explore threats to flood recession agriculture and how rivers can be managed in ways to restore and maintain this form of farming. I’ll also continue to explore the concept of “good floods,” and the surprisingly important role of muddy waters for a safe and sustainable world.
