Guest Opinion: Dr. Tim Ball
Petula Clark sang, “Don’t sleep in the subway, darling. Don’t stand in the pouring rain.” More helpful advice would urge, “Don’t live in the floodplain, darling. Don’t you know it’s pouring rain?” It’s called a floodplain for a reason. The dangers of flooding mostly involve people living in dangerous places. Why are people allowed to live in these regions without being forced to accept full responsibility for their actions? They are encouraged by governments and insurance that enable bad practices, questionable, and unnecessary behavior.
There was a time when living near a river was important for transport, water supply, waste removal, and even food supply. We don’t need to live close to rivers or at least within the area identified as the floodplain. If you live there, flooding is inevitable, even if flooding protection is in place. In fact, the protection creates a false sense of security. Inevitably the protection will fail through neglect, accident, or water levels that exceed the design capacity.
Engineers design flood control structures based on the frequency of events. Usually, it is for the one in 100-year event. Most think this means if you have such an event then another one will not occur for another 100 years. It is known be a few names the return period, recurrence interval, repeat interval, or expected frequency. It is defined by
Where n = number of years: m = number of occurrences of flood events
There are several problems with this approach, many now producing headlines about global warming and climate change.
The first involves the changing patterns of precipitation. There are very few records of precipitation, and most are less than 100 years long. The greatest range of variation of precipitation occurs in the middle latitudes in association with the changes in the latitude and amplitude in Rossby Waves along the Polar Front. Much longer time periods of precipitation are now occurring. These are not because of man-made climate change but the natural mechanism. The IPCC don’t consider these because of the restrictions of the definition of climate change to only human causes.
Second are the ongoing changes to the river as flows vary with changing precipitation. These are superimposed on the natural changes in a river as it evolves from youth to maturity to old age.
Third are man-made changes in the river basin that alter the pattern of runoff spatially and temporally.
All these issues confronted the Assiniboine River Management Advisory Board I was appointed to Chair. We were charged with creating a total basin management strategy. (Figure 1)
Figure 1
The first challenge was to come to grips with the great range of flow. Like most Great Plain’s rivers, it varied considerably. Fortunately, what triggered the demand for a management strategy was a swing in 6 years from the lowest to the highest flow in the then 94-year record. Figure 3 only covers from 1906 to 1973 but illustrates the range of maximum and minimum flows. Sedimentary evidence indicates much longer and larger scale wetter cycles. For example, Figure 2a, 2b, and 2c are cross-sections through a dune located half way along the current Assiniboine River near Brandon. They show three distinct well-formed paleosols formed through prolonged wetter spells.
Figure 2a (Source: Author).
Figure 2b Top of Dune – Two paleosols visible
Figure 2 c Middle dune paleosol.
The flow rate was important along the river, but also because the Assiniboine is the major tributary of the Red River of the North. The Red consistently causes urban flooding problems at Minot, Fargo in North Dakota, and Winnipeg. The City of Winnipeg built a massive diversion channel called the floodway that takes water out of the River south of the city and returns it north of the city (Figure 4). It effectively doubles the river capacity over the length of the diversion channel. It was built based on the modern record of flooding. The recurrence frequency considered a one-in-100-year flood including the 1950 event that triggered demand for flood control.
In fact, precipitation pattern changes much more frequently and widely than any 100-year record could accommodate. They ignored the historical evidence of the 1826 flood that was three times larger and reports of an even bigger flood in 1776, which coincides with the Little Ice Age. The 1826 flood was approximately a one-in-400-year event. Another flood of this magnitude occurred in 1996, and the floodway was inadequate, and though it alleviated to some extent, it forced them to expand the floodway.
Figure 4
There is a reason government provide flood insurance in the US. Private insurance companies won’t get involved because living in flood prone areas is asking for trouble, a self-inflicted wound, and governments often create or aggravate the problems by such actions as changing the surface.
In climate, most are aware of the urban heat island effect (UHIE), but that tends to focus on the temperature. An important cause of the temperature change is the changed surface and altered rates of runoff and evaporation.
The greatest surface changes are in the city center: an area called the Central Business District (CBD) with almost 100% impervious surface. Even the suburbs are at least 50 percent impervious surface. Figure 5 shows an average suburban lot and impervious surfaces.
Figure 5: Average suburban lot and impervious surfaces
Extensive drainage systems are designed to carry water away quickly. The water stays around in the countryside and evaporates slowly or is used by plants and transpired slowly, both processes creating cooling.
Figure 6. Rates of Runoff Urban/Rural
Figure 6 shows how these changes alter the peak at which the water reaches the river channel. The channel develops to accommodate a certain runoff rate so when water arrives too quickly flooding potential is increased.
Most rivers flood. The channels they create are for average natural flow, but if precipitation increases the channel will fill. The first stage is “bank full” when water reaches the top of the banks. Once water flows over the bank, it is in “first flood stage” and covers an area called the first flood plain. (Figure 7)
Figure 7: Thalweg is deepest part of a channel. Levees form from silt deposited during flooding.
Nobody should be allowed to build in that floodplain. Dikes to contain the river should not be allowed either because when breached catastrophic flooding occurs. Also, they prolong the flood because they prevent water returning to the river.
It is an event that occurs naturally in the old age stage of river development as a broad flat floodplain develops. Once the first flood stage occurs, water flowing along the edges of the river is slowed, and sediment is deposited creating levees. They deflect small tributaries from entering the river, so they flow parallel in a distinctive pattern known as a yazoo stream (Figure 8).
The precipitation patterns over long periods change much more than anything measured in the modern instrumental record. There is no need to build in the areas flooded shown in the following pictures of Calgary (9) and High River (10) Alberta, and Tewkesbury (11), UK.
Figure 10
Figure 11 shows the church builders knew long ago where the dry, as well as the moral high ground was located. Now with our faith in engineering, we are more arrogant and think we can ignore the long term patterns of nature. So, we need a new song, “Don’t live in the floodplain darling”.
Convert those floodplain areas within all cities, especially in the centers. They need more parks to give people access to nature, ameliorate the impact of the UHIE, and save the costs of dealing with the loss of lives and damage to property that floods inevitably bring. It doesn’t matter if the record is inadequate or if you only built for a 100-year flood to save money. When the 100-year event aggravated by changes to the urban area or the inevitable 400-year event occurs, it overwhelms and traps people who don’t understand recurrence frequencies. You can use the floodplain, but only with the ability to let nature use it for its designed purpose when she chooses.
Interesting points are made, but every spot on this planet (even high ground) is geologically active in the long haul. Predicting rare events (100-year, 500-year) is a fool’s game. Regular occurrences like annual floods are another matter – but even in those cases, “clean up and carry on” may be the most practical policy.
Adapt, adapt, adapt – and cope with reality. Look at Holland. Look at Venice. Some very clever “floating home” designs have been developed for new structures in places with high water conditions on a regular, periodic basis.
The cost of “relocating” everyone (or denying land use) because some event MIGHT happen (like a flood or lahar event) is ridiculous. All life involves risk-taking.
Ellen,
I agree generally with your outlook, and would blend in some of RobP’s pragmatism (up-thread).
Everywhere has something going on and it doesn’t have to be geological. The social dysfunction of some scattered, remote communities, with high alcoholism and suicide stats could prompt the call to not live there. Don’t live downstream of a dam. Don’t build under a volcano, don’t live in Tornado Alley, don’t live below sea level; avoid forest fire “interface” zones.
And then, there are all the bizarre misfortunes that befall individuals, but don’t get the big headlines. I was flooded out by peripatetic beaver plugging a culvert.
Nonetheless, an interesting article from Tim Ball.
Ideally active flood plains should remain agricultural land dedicated to annual crops. Perennials and woody plants often do not do well when flooded.
Levees should be built to slow the river and maximize temporary water impoundment to increase sediment deposition on the active flood plains which enriches and renews topsoil.
The number, size, and cost of buildings on floodplains should be minimized, and they should be constructed on elevated ground (possibly the levees themselves) whenever possible.
Permanent structures, office buildings and residential buildings should be relegated to elevated terraces.
Insurance companies could drive this. In California they have chosen not to provide fire insurance to buildings with wooden shingle roofs located in high-risk areas (outside city limits), and because of the widespread risk of earthquakes in the state, building with unreinforced masonry is simply banned.
Sediments delivered by floods contribute to soil; mankind has benefited and thrived on fertile floodplains and river deltas for ages. Plans should be based on and reflect realistic first-rate local geomorphology, with practical risk/return analysis. Abandoning all shorelines and floodplains to avoid all risk seems way out of proportion.
I highly recommend the reading of “dirt – The Erosion of Civilisations” by David R, Montgomery to understand how mankind has always, it seems, braved the wrath of Mother Nature.
Relevant to this discussion is this from his Rivers of Life chapter:
Good reading explaining lots of other ways we mistreat our local environments with short-sighted thinking.
Having worked with flood and drainage districts for many years, here in western Washington state, I could not agree more with the Ball’s points. I go around telling anyone who’ll listen that urbanizing the floodplain is a universally stupid idea.
* The floodplain is the river’s hydraulic shock absorber; what is called “the river” is in fact merely its meandering, low-flow channel.
* There are only two kinds of earthen levee: those that have broken and those that will, and the higher you build them, the more catastrophic the eventual breach will be.
* Floodplains (usually farmland) are developed because the land is cheap and the short-term profits and tax revenue consequently high. But if the same local governments that permit it had to pay for the enormous cost of flood damages themselves, instead dunning the federal taxpayer, floodplain development would stop TOMORROW.
Tim Ball, a well written article on an appropriate topic. It helps in the discussion of whether to consider some flood plain people as climate refugees or should be considered just short sighted people.
I would add that one should not build a structure at the level of the flood plain or if one does then build it high up on stout stilts well above the highest (worse case) flood level. The stout stilts need very serious foundations able to withstand: a) water flow pressure; b) being hit by massive floating objects in the water flow; and c) weakening due to seepage into the ground around the stilt foundations. One would also need to make sure to have redundant diesel generators and ample fuel tanks.
John
It true that we should not be developing more properties on floodplains.
People at one time had good reason to want to live adjacent to major rivers.
But with piped supply of water and transport by road and rail, those days are gone.
HOWEVER – that doesn’t mean that we should simply abandon land and properties that have been historical effectively drained by man. And certainly not that we should abandon people in such regions to the whims of environmentalist obsessives who wish to return the built world their fantasy idyllic wilderness governed only by the forces of nature.
A recent study concluded that 9 out of 10 of the properties that flooded in Somerset, UK – did so because of inadequate drainage. i.e. that had the systems of drains and pumps been maintained as intended then the flood would have only affected an extremely small number of low lying properties.
They also concluded that this lesser flood would have been shorter in duration.
In summary, we can see that had there not been a cessation of regular dredging and maintenance then critically – their would have been NO news stories about Somerset in 2014.
And with no news story – there would have been no disaster to blame on terrifying global warming and rising sea levels.
No disaster in Somerset – would therefore have been a disaster for the eco-left.
And so their plans have worked out better than even they could have ever dreamed:
http://www.westerndailypress.co.uk/Better-pumps-dredging-stop-floods/story-27574691-detail/story.html
Very nice lecture on how rivers work and what they are there for. I filled sandbags for the 1950 flood which was a doozy. I remember with fondness the endless supply of sandwiches and coffee that women citizens delivered to the trailers at a number of spots were bagging operations were taking place.
My first engineering job was with, IIRC, the Water Control Branch of the Manitoba Department of Agriculture in the design and early construction phase of the Greater Winnipeg Floodway in 1961(2?). Dr. Ball, you probably knew a fellow by the name of Locke and another by the name of Frank Render (whom I graduated with). I believe they were at the Ministry for many years. I worked in the hydrology part of the data gathering. A prime job was, in addition to putting in wells with piezometers along the right-of-way, was to measure all the farmers’ wells within a swath on either side of the planned channel in preparation for the inevitable claims that they needed a new well because of the floodway. Actually, the farmers’ wells didn’t change noticeably and we didn’t expect them to, but when claims came in we already had their records pre and post and had with a number of them already advised them to drill a modern decently installed well that they needed with or without the floodway.
At the time, the GWF was the second largest excavation project in the world after either Suez or the Panama canal. There is no question that it was a technical and economic success, but, of course any large engineering works need maintenance and upgrading. I didn’t follow its biography much after I left Winnipeg in 1965 (I was back to complete an MSc a few years later but then gone again).
Also, in other work with the Ministry at the time, I did a groundwater exploration project in the Souris area in southwestern Manitoba (town supply and stock watering) and discovered a buried main channel of the Missouri River when over 100,000years ago, before the continental glacier covered the ground, this river actually flowed north. It was identified by the gravel being a brown quartz with petrified wood fossils and “opaline wood” – wood cells replaced with opal. It had been traced along its route through North Dakota and into Saskatchewan where they lost it when, apparently it made substantial bend. I was drilling holes to shale bedrock about 30 to 50 feet when suddenly we nearly lost the whole drill string and had to put the brakes on as it ultimately went down about 200 or more feet into the distinctive gravels and the sweetest water in Manitoba. When the glacier blocked flow northward and things froze up, the old Missouri waited until it melted and made Lake Agassiz which was bigger than all the Great Lakes put together. This major part of the Missouri then was captured by the headwaters of another south-eastward flowing tributary of the Mississippi, the modern Missouri, and the water flowed southward leaving much of the old channel buried.
I also was the guy that got sent out all over southern Manitoba to sites where farmers and municipalities planned to drill wells. It was the law that they follow certain procedures because of bad experiences with washed out artesian wells. One job was actually plugging a runaway artesian well in western Manitoba, a thing I didn’t have a clue on how to do. I took the driller (name of Tillepaugh) and his rig to see what we might do. We got there to find a sizable little lake in the hollow field where the farmer had had the hole drilled and it was centered by the ugliest swirling waters I had ever seen. I said to Tillepaugh, what in hell are we going to do with that! He hummed and hawed and then said maybe we can plug it with a telephone pole, the hole will narrow with depth. We’ll need a dozer and chains to tie on while I back the rig to the hole with the telphone pole and we’ll need a cement truck full to pour the cement in the instant we stem the flow enough. We had to time it well because the pole won’t hold it back for long and it could shoot up into the air kill us if it gets away on his. It worked like a charm with dozens of farmer spectators shaking their heads that it wouldn’t. We gerry-built a chain hook-up to the hydraulic drive for the drill stem and raised the pole up along the mast of the rig. We rammed the telephone pole down and the waters quieted and then with troughing from the cement truck, poured the whole truckload down the hole and let it set for the day. We probably left a story or two behind us.
Gee, your article tapped into some nice old memories.
🙂
Nice memories. From one Eng to another.
Actually the floodplain is as much a part of the river as the channel. It’s just a part that may not be in use at any particular time.
“Nobody should be allowed to build in that floodplain. Dikes to contain the river should not be allowed either because when breached catastrophic flooding occurs.” Nailed it – but who listens when land use is a political matter given that land in non Green Belt areas is in short supply, as it is in most developed nations.
BTW: The EU banned dredging (which had been mandated for centuries as a flood control requirement in certain locations) as a means of flood control. With the Cumbria floods, guess what contributed the most to their massive flooding problem? With the best of intentions and all that…..unintended consequence.
Actually they didn’t ban it, they just required that the dredged silt be treated almost like hazardous waste and not be used for embankments or for dumping at sea unless so treated. But it had the same effect as banning.
The Rio Grande in Albuquerque New Mexico is instructive
When white settlers arrived, the river had natural levees that would breach from time to time in high discharge floods. Bottom land near the river (floodplain) was mostly used for pasturage. Over time, the city center developed and spread into floodplain lands
Following major flooding and damage in the 1940s, the U.S. Corps of Engineers channelized the river within permanent levees, and the river silted-up its channel (no longer able to discharge excess silt over the levee tops). The river bottom actually became higher than the elevation of bottom lands outside the levees, and the bottom lands became waterlogged. So the USCOE built drainage ditches to drain the bottom lands, which allowed for residential and commercial development back in the drained lands.
The artificial floodplain contained by the artificial levees is now overgrown by cottonwoods, willows, and invasive water-loving trees and shrubs (tamarisk, mesquite, salt cedar, and others). The tree-hugging locals lovingly refer to this as the “Ancient Bosque Forest”, clueless to the fact that it did not exist prior to 1940. More ironic, the City of Albuquerque has to pump groundwater for municipal supply because the surface flow to the Rio Grande was completely “appropriated” before any significant population existed in the area – appropriated by farmers downstream in the Elephant Butte-El Paso region. The Bosque “forest” today consumes at least 25% of the stream flow by evapotranspiration, which is lost to both the city and the downstream farmers.
This fabulous mess was brought to you by the Federal Government, using your tax dollars to solve problems that were created by government mis-management – – and by local foolish uses of floodplains.
You ‘d think that a town named High River would be a clue not to move there. High River, Alberta, was flooded in 2013 because of a … wait for it … high river!
High River, like many Cities and Towns along waterways, grew without benefit of planning or engineering. It originally was a low spot in the river bank with a good gravel bottom that allowed fording of the river when it was low. An enterprising group built a ferry to take people and goods across the river at higher flows with a house for the ferry folks. Gradually a community grew up around the ferry and became High River. Parts of the City has flooded many times. During the last flood, one of the worst hit areas was behind a dyke, once flooded, the water couldn’t get out again.
Very good article. I am still reading, but two immediate points.
Fig 7 looks very much like the southern shore of the Ottawa river.
Fig 8 reminds me of the source of the phrase “Up the Yazoo”.
You can build in a flood plain, provided you build on a barge.
http://www.motherearthnews.com/nature-and-environment/unsinkable-shelter-on-a-barge-zmaz82jazgoe.aspx
I’ve been alive long enough to have learned, through experience, that 100 year floods happen every 20 – 25 years. Yeah, they’re not supposed to, but they do. They always do.
A 100 year flood is meant to be a once-in-a-lifetime event If they are now coming at 25 year intervals, it’s a once-in-a career event for hydrologists – which is much the same thing…
Very good article, Dr. Ball. Three items to consider:
FEMA and other US agencies also use “annual exceedence probability”. For example,
http://pubs.usgs.gov/gip/106/pdf/100-year-flood-handout-042610.pdf
The word that describes the (lack of) change in the long-term hydrologic record is “stationarity”. The stationarity tar pit is wide, deep, but very inviting.
https://www.researchgate.net/publication/268283405_Modeling_and_Mitigating_Natural_Hazards_Stationarity_is_Immortal
The tar pit includes hydrologic statistics. For a start, there is the adopted methodology for estimating the “100 year” event using log Pearson III statistics:
http://acwi.gov/hydrology/Frequency/B17bFAQ.html
http://water.usgs.gov/osw/bulletin17b/bulletin_17B.html
Professor Leopold, one of the fathers of limnology, taught me that the 10-year flood plain was the level that flood two or three time in 10 years. A 100-year flood plain floods two or three time in 100 years. In Wheeling, West Virginia the is Wheeling Island, the site of many homes, businesses, a football stadium, and a large casino. The island floods quite often, which is logical since the island was built by floods that deposited all of that mass. This means floods much higher than the island on a regular basis.
Hey this looks like a great place to build a settlement. What do the natives call it? “High River”. I wonder why? Looks just like a little creek to me. 100+ years later we are still building and living there.
Silly Earthlings (Marvin the Martian)
After seeing the City of New Orleans rebuilt in place after being all but destroyed in many areas, I have little hope that you warnings will be heeded, Dr. Ball.
After all, if people are too stupid to move a wrecked city to a new locale after being wrecked, even when the city is below sea level and sinking further every day, even when the city is in the most hurricane prone stretch of coastline on the entire continent, and perhaps the entire world, and even when the city is astride one of the largest rivers in the world, which is higher even that the sea that it also sits below.
Yes, people are way too stupid to take good advice, even when they just witnessed firsthand a small taste of the disaster that can be expected to reoccur on a regular basis.
How timely. Today’s LA Times….a bastion of AGW hype….had an article on “our country’s first Climate change refugees” from Newtok, Alaska, a small (350 people) village on the banks of a river. It goes on lamenting how federal assistance is slow helping these people move to safer, higher ground. “To truly make a lasting client change legacy, Obama must take seriously the issue of climate relocation”. The real issue is the same anyplace you have moving water next to land…..erosion. The village has already relocated from its’ first location due to erosion and now it must move again. The article gave an image of townspeople wallowing in melted permafrost during the melt season due to “Climate Change”. It also says we should be making plans for “thousands more from along America’s most fragile shorelines will embark on a great migration inland as their homes disappear beneath the water’s surface.” Reality should be catching up with and surpassing the hype soon.
Great. Another reason for lefties to employ to encourage the use of the force of government to tell people were they can and can not live. Its bad enough that lefties are working diligently to force people into high density housing.
Again – I think a lot of folks need to curb their “inner Chicken Little” and put this risk into perspective. Adapt, find solutions, dredge if need be, keep moving. I’m in my mid-sixties and I’m originally from Pittsburgh PA (now living in western Washington State). I was raised listening to first-hand accounts of the Pittsburgh Flood of 1936 and the Johnstown Flood of 1937; scars remained on the landscape and landmark buildings. There was also extensive flooding in the U.S. east in 1951. All regions and places experience severe events: floods, hurricanes, tornadoes along with tsunamis, earthquakes and volcanoes. Such is life. I worry that our young have become so obsessed with perfect-planet theory (“sustainability”) that plans have become cripplingly and foolishly risk averse.
2011 floods in Brisbane, Australia.
http://www.abc.net.au/news/specials/qld-floods/
‘Aren’t we lucky to have water views from our backyards?’
Known flood levels in the same area since the early 1850’s:
http://www.bom.gov.au/qld/flood/fld_history/brisbane_history.shtml
From the Brisbane City Council’s web site:
Even when an area is a known flood plain, they still build on it then scream when a flood occurs (plus blame AGW as well).
The fools that call them drongos are no idiots (an Australianism)
We may also reach this logical town planning through socio-cultural processes, just like that picture of Tewkbury church on a slight rise. The last time I bought a house I said (loudly) don’t show me anything in a Watermeadow Drive or a Riverside Walk. And the guy next to me laughed, and said ‘I said much the same thing’. The message is getting out there, that riverside properties are problematic to live in, impossible to insure, and difficult to sell. (Unless builders do the sensible thing, and build these properties on stilts, with the car port under the house.)
R
It is hard to control floods in the plains.
Better to do it in the higher grounds.
An excellent read for flooding/flood management:
http://www.amazon.com/Rising-Tide-Mississippi-Changed-America/dp/0684840022/ref=sr_1_sc_1?ie=UTF8&qid=1453812200&sr=8-1-spell&keywords=missiippi+flooding+1927