2660. Thoreau’s Distressing Canoe Trip

By John Waldman, The New York Times, July 12, 2017

Henry David Thoreau

Six years before he moved to Walden Pond in 1845 to ponder life and live deliberately, Henry David Thoreau spent two weeks canoeing rivers in Massachusetts and New Hampshire. The voyage was an epiphany for him.

At the time, the nation was becoming giddy with the promise of industrialization, an enterprise greatly dependent on rivers for power and waste disposal. But Thoreau, born 200 years ago on Wednesday, foresaw the ravaged futures of these increasingly commodified rivers. His book “A Week on the Concord and Merrimack Rivers,” self-published in 1849, offered his account of what was actually a two-week trip with his brother John.

Already in 1839 the water-powered wheels and belts of the Industrial Revolution were whirling fast. Though Thoreau was not yet well traveled in outdoors New England, his insights were distilled by watching the rivers’ migratory fishes. Dependent on clean and free-flowing water to swim upriver from the sea to spawn, these fish even then were being stymied by dams. He was so distressed by what he saw that he was stirred to ask a still haunting question: “Who hears the fishes when they cry?”

Two centuries later the answer is clear: not many. Once, rivers on the Atlantic coast “ran silver” with thrashing multitudes of ecologically and societally important fish like salmon, herring and shad as they completed their grand life cycles. They ran so thickly that it was said one could walk “drishod” across their backs.

Accounts of early colonists marveling at the contrast between these unadulterated runs and the long-impoverished watercourses of their European homelands speak of abundances that would be difficult to imagine today. To these colonists, this bounty was an expression of Divine Providence.

Now these same Atlantic rivers are fettered and tired, falling to the sea with the stilted tempo of the subjugated. Runs of the dozen or so river-sea migratory fish have, in many cases, been obliterated or reduced to fractions of their former plenitude. No longer ecologically relevant or societally important, they have become, in effect, “ghost fishes.”

A failed restoration program for salmon in the Merrimack was canceled in 2013, and the river’s sparse shad and alewife schools no longer color its waters silver each spring. In fact, the visitors center at a fishway in Manchester, N.H., that invites guests to “Celebrate the Magic of the Merrimack” has everything except abundant fish; in most years few reach that far upriver.

Atlantic salmon in all American rivers combined may have once reached a half million; in 2016, fewer than 600 were counted. On the Susquehanna River, the restoration target for American shad migrating past the fourth dam above tidewater to their historical spawning grounds is two million, a modest number compared with the natural run. But in recent years, fewer than 100 have made it that far up the river. On other rivers in the Northeast, the spawning runs are likewise depleted, down by as much as three to five orders of magnitude from early colonial times.

Thoreau was prophetic in his apprehensions about dams. Though society has degraded rivers and reduced fish runs through pollution, overfishing and a host of other grievances, no single action has caused as much injury as the construction of barriers along their migratory routes. And decades of experimentation with engineered devices, like ladders to allow these fish to pass dams, have failed to reverse these declines.

As Thoreau lamented, “Poor shad! Where is thy redress?”

The removal in 1999 of the Edwards Dam on Maine’s Kennebec River and the subsequent explosion in its fish populations offered an answer to his question, showing that these rivers can recover. Now that other energy alternatives are available, like wind and solar, society shouldn’t accept the presence of dams that produce nominal hydropower at the cost of the health of major Atlantic rivers.

Thoreau held hope that the end to the great fish migrations would resonate. “It will not be forgotten by some memory that we were contemporaries,” he wrote. But he also seemed to understand that, for the time being — and probably considerably longer — the fish were largely on their own. And so he urged them on with a message of self-reliance: “Keep a stiff fin then, and stem all the tides thou mayst meet.”

On this Thoreau bicentennial, most of the waterfront mills that drove the Industrial Revolution are shuttered or have been converted to other uses. More than two centuries after Thoreau first witnessed the Industrial Revolution begin to strangle our rivers, the shad’s redress should be apparent: the removal of the dams that once powered a now completed chapter of American history.

John Waldman is a professor of biology at Queens College and the author, most recently, of “Running Silver: Restoring Atlantic Rivers and Their Great Fish Migrations.”

1981. From the Mississippi to the Ganges, River Deltas Are in Major Trouble

By Chris Mooney, The Washington Post, August 6, 2015

False-color composite image of the Mississippi River delta, as acquired by the ASTER instrument on NASA’s Terra satellite on May 24, 2001. Image provided by the USGS EROS Data Center Satellite Systems Branch as part of the Earth as Art II image series (Courtesy of USGS EROS Data Center Satellite Systems Branch)

A river delta is, by definition, a place in flux — coastal land naturally sinks, and is naturally rebuilt by the flow of a vast river that carries in new sediment. Across the globe, from the Amazon to the Nile to the Yangtze, we humans rely on such deltas for the many benefits they bring — access to fisheries, good locations for shipping, and much else.

But we don’t just rely on them — we change them. We dam rivers upstream and channelize them downstream – actions that reduce the flow of sediment and, thus, the growth of land. Meanwhile, we cut channels through wetlands and cause land to sink further by pulling lots of oil and gas and water out of it.

Such changes have an insidious consequence: Even as they entice larger populations to live on deltas by providing jobs and the semblance of environmental stability, they also increase long-term vulnerability to storms and floods by exacerbating the land’s sinking. Meanwhile, global warming makes the whole dynamic worse because it introduces a huge arrow pointing in only one direction — sea level is going up, and up, and up.

Now, a sweeping new study released in Science Thursday takes a comprehensive look at how much such factors are increasing the vulnerability of 48 major global river deltas, the home to 340 million people — including the Mississippi River delta, which lies between the city of New Orleans and the sea.

“We characterized the rate of change of risk in delta systems due to combined land subsidence, sea level rise, geophysical setting, and socio-economic capacity to protect themselves,” explains lead study author Zachary Tessler of the City University, who conducted the research with scholars from three additional universities.

Here’s an image Tessler provided with the research, showing the loss of delta wetlands in Louisiana over the past four decades:

The study used multiple datasets and indices to examine changing risks to river deltas based upon 1) their inherent risk of storms and floods; and 2) how much humans are exacerbating those risks by changing their landscapes in a way that causes land to sink, even as seas rise.

Along the first axis, deltas range from the Orinoco in South America, which faces relatively few flooding and storm threats, to the Yangtzee and Han, where these risks are very high.

When it comes to human perturbations of the system, meanwhile, river deltas range from the pristine Yukon in Alaska, which is relatively lowly populated and has been little changed by humans in a way that would make it more vulnerable (much of it is a wildlife refuge), to the Ganges-Brahmaputra of Bangladesh and India — home to over 100 million people, where human activities and sea level rise are pushing the risks forward dramatically.

Based on these two factors — how much human activities and sea level rise are changing a delta and worsening its plight, and how much it is exposed to storm and flood risks — the study found a complex tapestry of changing risks, depending on the delta. On the one hand, the Yukon wasn’t at much additional risk at all. “It’s definitely clear that some of these deltas are almost completely untouched, that tends to be at the high latitudes,” says Tessler.

However, most of the deltas showed at least some increased risk, and some showed quite a lot of it. In particular, the heavily populated Krishna and Ganges-Brahmaputra deltas had the most rapidly growing risk of flooding related disasters. “They have…lots of dams, lots of development on the coastline, wetland loss — we expect the relative sea level rise that’s happening there to have a large impact on the risk outcomes of the communities,” Tessler says.

Indeed, Bangladesh has historically been the home to the deadliest tropical cyclone (or hurricane) disasters known to history, including the 1970 Bhola cyclone, which struck this very delta, the Ganges-Brahmaputra, and caused 300,000 to 500,000 deaths.

But there’s another key factor involved in determining a given delta’s risks — a society’s wealth, which translates into its ability to protect itself. Thus, while the Mississippi River is heavily managed and has been changed nearly beyond recognition by humans, the delta also has a high level of artificially imposed resilience — with vast levees along much of the river to prevent flooding, not to mention New Orleans’ huge new hurricane protections.

A similar story can be told about the Rhine, heavily altered by humans but also the home to arguably the world’s most impressive flood protections, constructed by the Dutch.

“A high capacity for investment in risk-reducing technologies…is the primary reason that several wealthy, developed deltas today have relatively low risks,” the study found.

But that may not always be the case. The research found that if the cost of building flood-defense infrastructure increases steadily over 100 years — as might be brought on, for instance, by rising energy prices — then the rich but heavily exploited deltas like the Mississippi would see a spike in vulnerability. In that scenario, a delta like the Mississippi “reverted back toward expectations based on geophysical hazards and anthropogenic change alone.”

That’s a sobering message this year, as most observers of New Orleans 10 years after Hurricane Katrina are likely to look at its gigantic and costly hurricane protections and see them as a sign of reassurance. And they are — but Tessler is suggesting that it’s a little more complicated than that.

“If you want to maintain your [level of] risk, in light of increasing cost, you need to spend increasing amounts of money,” he says. “And while you’re doing that, you’re not addressing the fact that land subsidence is increasing. So your costs are rising.”

Deltas, after all, have been doing their thing for thousands upon thousands of years — flooding, washing in sediment, rebuilding land. But we changed the system — meaning that simply building higher, on sinking land, may not be enough of a sustainable solution.