Could George H. Henshaw's have saved New Orleans from the catastrophe that was Katrina?

by Peter Duveen

PETER'S NEW YORK, September 19, 2010--A letter arrived at the New York Times in early January of 1891.[1] It was submitted by George H. Henshaw, a civil engineer who had practiced his art in Canada, Denmark, and various locations in the United States. When his position as resident engineer of the lock and canal at Ste. Anne de Bellevue just outside of Montreal ended in 1888, he joined his wife, Cornelia, and their six children at his mother-in-law's home on State Street in Brooklyn Heights, New York City.[2]  It was from this enclave of urban respectability that Henshaw would pursue various projects while searching for work.[3]

George H. Henshaw, civil engineer
George H. Henshaw, civil engineer and inventor. 

Henshaw had been preoccupied with the problem of periodic flooding of the area surrounding the Mississippi River at least since 1881, when he tells us he submitted a paper in a competition sponsored by the King of Belgium on the improvement of harbors on sandy coasts.[4] As an engineer dealing with canals and other water works, he had studied water flow and erosion, and wished to apply his expertise to a vexing dilemma: how to keep the Mississippi navigable while protecting the population that had permanently settled in what was formerly the flood plain of the river. Since the river overflowed only periodically, and severe flooding was even less frequent, the population had seen fit to establish permanent residences in the countryside surrounding the river, and to erect and maintain mounds of earth at the banks of the river in order to prevent the water from flowing into settled areas. These reinforced mounds of earth are what are generally referred to as levées.

One thing was certain: Henshaw believed that the levée system was doomed to failure. He observed that silt and other material that would have been deposited in the river's flood plane were now constricted to the narrow and artificial confines of the river bed. This deposit would eventually displace a significant volume of water, which would have no place to go but over the levées. The cycle of failure, according to Henshaw, would persist even as the levées were built higher and stronger in an attempt to protect residents from the river's overflow.

Henshaw believed he had a solution. When he was engineer on some of the rail lines in Canada and Denmark, he had observed the manner in which snow banks are formed and shaped by the wind. [5] Small obstacles to the wind created either a buildup of snow, or deep furrows within snow banks, depending on where they were situated. This shaping of the accumulated snow by the wind occurred according to strict natural laws, and Henshaw believed that his observations of the action of the wind could be applied to the manner in which the silty riverbed reacted to the flow of water. Being without employment after leaving Canada, he occupied himself with a solution to two related problems: the periodic flooding of the Mississippi and the erosion of local beaches.

In 1882, Henshaw addressed the problem of Mississippi flooding in a paper, "A Plan for the Improvement of Navigation and the Prevention of Floods in the Mississippi River." [6] At that time, it had been argued that by narrowing the banks of the river, the water could be induced to flow more rapidly, and would be more apt to carry away sediment. Henshaw noted in the 1882 paper that it was not velocity alone that determined whether sediment was carried away by the river, but turbulence at the riverbed itself. [7] This turbulence, if artificially maintained, might result in the natural deepening of the river channel through the carrying away of sediment.

Some success had already been achieved in deepening parts of the Mississippi without resorting to dredging or levées. James Buchanan Eads (1820-1887) had managed to fulfill a contract around 1879 to deepen a heavily trafficked portion of the Mississippi delta known as the South Pass, by the construction of jetties into the river. He was required by his plan to maintain a depth of 30 feet over width of 350 feet for a full quarter, and then maintain this same breadth and depth for 20 years [8]. His accomplishment was widely acclaimed, but the technology he had used was not the one earnestly pursued by the Army Corps of Engineers, which eventually dropped Eads's successful innovations and soon moved to a policy of focusing on levée construction and repair to constrict the river's flow, a policy Henshaw warned would result in further flooding. [9]

South Pass, Mississippi Delta
Channel of the South Pass, Mississippi Delta, 1874 map.

In a second paper on the subject, published in March of 1889 in the Journal of the American Society of Civil Engineers and entitled "The Improvement of Channels in Sedimentary Rivers," Henshaw argued for the installation of fences composed of permeable and flexible material such as willow branches, placed strategically in some portions of the river bed and banks to protect areas from erosion while promoting erosion in others through the creation of turbulence. [10] In this manner, Henshaw strongly believed it would be possible to deepen channels of the river sufficiently to considerably reduce if not eliminate reliance of the levée system.

In 1890, Henshaw was awarded a patent for an invention "by which river channels may be formed and preserved, bars off the mouths of deltas removed and the channels through deltas deepened and preserved, sea beaches repaired and protected from erosion, shifting shoals fixed, and estuary lands reclaimed."[11]

George H. Henshaw's invention
George H. Henshaw's arrangement of materials and their projected action upon the river bed and banks.

Apparently, his frequent entreaties to the Mississippi River Commission, established by the U.S. Congress in 1879 to manage the flooding of the river, were to no avail. A new and devastating flood in 1890 demonstrated that the best efforts of the commission were not bearing fruit, despite the tens of millions of dollars applied to the commission's various projects at different points on the river. It was this renewal of natural disaster that likely prompted Henshaw to appeal to the public in a lengthy letter penned to the New York Times.[12]

George H. Henshaw's invention
Works along the channel of the river, view from the top. Apparently the arrangement of materials would have narrowed the confines of the river
to in between the narrowed section, as the deposit of sediment and the deepening of the channel progressed.

"No one now disputes," said Henshaw," that the Mississippi runs through an elevation which it has itself deposited, nor that this deposit still goes on. This being the case, it is plain that the deposit, which in ancient times spread itself far and wide, is now confined between the levées; therefore, unless the channel or channels be made to deepen and widen themselves in proportion to the deposit, the bottom must rise, and the height of the levées must be increased from time to time."

The commission, Henshaw suggested, had failed to prevent renewed flooding of the river because "more deposit has taken place than scour, for otherwise the flood would not have risen to so great a height." He predicted that "the country will continue to pay its millions for efforts in a futile direction until some change in that body's organization occurs. At present it is a close and absolutely uncontrolled organization." Henshaw complained that the proposals he had submitted to the commission had been "rejected with scant consideration."

Henshaw never was able to see his letter in print, for, as that newspaper noted, "the above communication was brought to The Times office by Mr. Henshaw three days before his death."

An obituary tells us that a heart attack felled the 59-year-old engineer at his State Street residence on January 10, 1891, just as he was completing preparations to leave for Guatemala to work on a new project, perhaps a precursor to the Panama Canal. [14]
His fruitless search for a response from the government had undoubtedly taken its toll upon domestic tranquility. Letters of consolation to the widowed Cornelia imply such. Upon receiving news of her father's death, Esther Henshaw wrote her mother that "his [Henshaw's] disappointments are all over, and when I think how short this life is even for the youngest of us, I feel that it is only a parting for a little time, and then we will be all together forever." [14] Another daughter, Sarah Henshaw Childs, observed that "dear Papa's life the past few years has been so full of sadness and disappointment. I cannot but feel how sweet to him must be that rest and peace which the world could never have given him."[15]

Many years of silence followed the death of this interesting civil engineer, so full of energy and so interested in the engineering issues of his day.

The story of his career was revived in subsequent years. In 1927, the Mississippi River suffered some of its worst flooding in several decades. In response, G. Herbert Henshaw, George Henshaw's eldest surviving son, and editor of the weekly magazine Brooklyn Life at the time, took a moment to remember his father's accomplishments.[16]
The editor explained that while while his father knew tides and currents would resist forceful means to control them, "they could be cajoled or induced to built up where they had previously eaten away, by playing into Nature's hands, and by experimentation of a small scale he (Henshaw) demonstrated that by the system of flexible and permeable barriers he had devised, a stream could be induced to flow in such a manner that its tendency would be to continuously scour out its channel and correspondingly build up its banks." He went on to explain that his father "had wasted an unconscionable amount of time between one circumlocution office and another" in an attempt to promote his idea.

"The idea was altogether too much out of the ordinary," said the son, "to appeal to the minds confined within mathematically exact and immovable levées and besides it came from a civil engineer or rank outsider." Some weeks later, at the encouragement of his readers, Herbert Henshaw once again brought to the attention of the government's engineers the concepts developed by his father, but had low expectations of their paying any serious attention. In a latter column, he did try to distinguish between his father's innovations and efforts by others that resembled them. "My father called his device the 'fish bone sand trap,' and I think what was chiefly original in his plan was the placing and anchoring of the permeable barriers. There is, of course, nothing new in the use of brush and other light material to protect shore fronts from erosion, but placed without regard to scientific principles they cannot be depended upon to produce the results desired."

We know that, in 2005, Hurricane Katrina was said to have been the cause of breaches in upward of a hundred levées, including breaches in a key levée in New Orleans that led to the flooding of a vast, populated area and the virtual shutting down and evacuation of the entire city, not to mention the deaths caused by this natural disaster, coupled with mismanagement of rescue and rebuilding. [17] Any technology that minimizes our reliance on levées must therefore be counted as lessening the risk of a repeat performance of massive levée failure. One might expect that engineers will revisit Henshaw's concepts and writings on the subject, and, in spite of the vast investment of resources into an apparently failed technology, will find a way out of the present dilemma in which floods are created where there would be none, and disasters aplenty await an unsuspecting public.

[1] George H. Henshaw, "Acts of the River Commission viewed by a civil engineer." New York Times, Jan 18, 1891.
[2] Obituary, Transactions, Canadian Society of Civil Engineers, Montreal, 1891, p. 365.
[3] Obituary Notes, New York Times, Jan. 11, 1891 p. 5. "For the last two years he (George H. Henshaw) had been in New York and Brooklyn developing an idea to protect beach fronts from the action of the ocean. It was his purpose to have tried it this year at Manhattan and Brighton Beaches."
[4] George H. Henshaw, "A Plan for the Improvement of Navigation and the Prevention of Floods in the Mississippi," Montreal, Witness Printing House, 1882, pgs. 13-14.
[5] George H. Henshaw, "Discussion: Improvement of Sedimentary Rivers," Transactions,
New York, American Society of Civil Engineers, May, 1889, p. 232.
[6] George H. Henshaw, "A Plan for the Improvement of Navigation and the Prevention of Floods in the Mississippi," Montreal: "Witness" Printing House, 1882.
[7] Ibid., p. 8.
[8] Mr. R. Brown, Captain Engineers, U.S.A. to Hon. G.W. McCrary, Secretary of War, Washington, D.C., "Letter from The Secretary of War transmitting papers relative to the payment of first installment of compensation to Mr. James B. Eads for maintenance of channel at South Pass, Mississippi River, for quarter ending October 30, 1879," Washington,D.C., 46th Congress, 2d Session Senate, Ex. Doc. No. 44, p.1.
[9] "American Experience. Fatal Flood. People and Events: The Mississippi River Commission and the Army Corps of Engineers." National Public Radio, Accessed Sep. 6, 2010.
[10] George H. Henshaw, "The Improvement of Channels in Sedimentary Rivers," Transactions. New York: American Society of Civil Engineers March, 1889, pgs. 110-116.
[11] U.S. Patent No. 419,121, "Means for controlling the shifting action of moving water on land."
[12] George H. Henshaw, "Acts of the River Commission viewed by a civil engineer."
[13] Amelia Henshaw to Cornelia Henshaw, Jan. 30, 1891, Museum of Brooklyn Art and Culture archives.
[14] Esther Holt Henshaw, to Cornelia M. Henshaw, Jan. 15, 1891, Museum of Brooklyn Art and Culture archives.
[15] Sarah Middagh Henshaw Childs to Cornelia M. Henshaw, Jan. 12, 1891, Museum of Brooklyn Art and Culture archives.
[16] George H. Henshaw, "The Mississippi Disaster," Brooklyn Life, May 7, 1927, p. 8.
[17] "2005 levée failures in Greater New Orleans." Wikipedia: the Free Encyclopedia.ée_failures_in_Greater_New_Orleans, accessed Sept. 6, 2010.