Regimes and Cycles, Rhythm and Flow

Originally Published on MAY 26, 2014  |  Nature Conservancy – Conservancy Talk |

I very well remember the day long ago when I read a scientific paper written by a PhD student named LeRoy Poff. In that paper LeRoy talked about the distinctive patterns of water flow that could be recognized when looking at a hydrograph – the graphical record of the day-to-day ups and downs in river levels. Different river hydrographs, explained LeRoy, exhibited different patterns. Some, such as snowmelt-powered rivers, were rather predictable in their springtime flushes and annual cycles, but others would flash and fall with the rain.

I had just assumed the helm of the Global Freshwater Program for The Nature Conservancy, and LeRoy’s story revealed an entirely new way of understanding the character of rivers. I called him that very afternoon to introduce myself, hungry to learn everything I could from him; we have been good friends and collaborators ever since.

Soon thereafter I read another wonderful paper, this one by Keith Walker of Australia, in which he referred to the water flow regime as the “maestro of the river orchestra.” Keith explained that much of what goes on in a river ecosystem is keyed to the rises and falls in river flows. The hydrograph is choreography. Floods tell salmon when to spawn. Low river levels dry out floodplains, enabling plant seeds to sprout.

Their words were music to my ears, and they gave direction and purpose to my conservation pursuits.

I’ve spent much of the past two decades listening to, learning from, and writing about rivers and their music. But most importantly, I’ve enjoyed the kinship of many talented scientists and conservationists trying to preserve or restore the natural wildness of rivers.

Twenty years ago we did not foresee how difficult this mission of river conservation would become. Thousands of big new dams have been built on formerly-wild rivers, and the water flows in more than a quarter of the world’s watersheds are now heavily depleted, some to the point of complete drying. Water development has brought much to our society and well-being, but at the same time, we did not have to lose so much.

We must do everything we can to teach others to hear this river music. It may be much-diminished in many places, but the land lays waiting to receive it – and the orchestra – once again.

Brian Richter has collaborated on more than 120 river projects around the world. In 2003, he wrote Rivers for Life, a book about environmental flow, with Sandra Postel. His latest book, Chasing Water: A Guide for Moving from Scarcity to Sustainability, has just been published by Island Press.

Pictured below: Map of global water scarcity This map illustrates the number of months each year in which more than half of the available water is being depleted for human use. Areas in orange and red are experiencing serious water shortages. Half of all cities with populations >100,000 are located in water-scarce basins. (Map reproduced from Richter and others, 2013. Tapped out: how can cities secure their water future? Water Policy 15 (2013) 335–363).