H2ONCoast

It’s funny how little conversations come around to turn into bigger and bigger dialogues. A few months ago fellow ex-Southwesterner Michael Campana (of the OSU Institute for Water and Watersheds, WaterWired blog, Aquadoc, etc.) and I had a long discussion of what if… What if the Southwest (including much of Calinfornia) found itself without enough water to go around? What if things were just inhospitable down there? Where would the masses of Phoenicians and Angelinos, Tucsonans and West Texans go?  We thought that they would probably come north to lovely green and watery Oregon of course!  Either that, or they would look towards purchasing some of our liquid gold for export, as I’ve blogged here before. Given the difficulty and probability of the latter excercise, Mike and I put more wheight on the former happening. Think 1930s Dust Bowl. Think of the diaspora of Katrina refugees out of the Gulf. Thing BIG.

Well, that conversation seems to have made it to the front page of the October 5th Oregonian with an article by Eric Mortenson.  The full article can be found by clicking here. The crux of the article is summed up by a quote from the article itself:

The prediction caused a collective grimace among the mayors, city councilors, engineers and planners in the audience. By 2060, a Metro economist said, the seven-county Portland area could grow to 3.85 million people — nearly double the number here now.

Then Lorna Stickel, a planner with the Portland Water Bureau, stood to ask a question. Does the population projection, she asked, account for the possibility of climate change refugees?

Brains have been spinning ever since. Because what if?

What if the American Southwest dries up, browns out, and those people now misting their patios in Arizona head to the still-green Pacific Northwest? What if Californians hit the road north in numbers far surpassing the 20,000 who now move to Oregon each year? What if the polar ice melts, oceans rise and millions living along coastal areas — or ravaged by Katrina-like storms — have to move?

What happens, Stickel later asks, “as we become more attractive and other places become less attractive?”

I also want to send kudos to Michael for putting this out on his WaterWired first and most importantly, for inspiring Lorna Stickel to bring up the question in the first place. Now, if only a combination of academic and applied colleagues in the SW and the PNW would be willing to try to play out this scenario, we might be able to generate some tools for planning BEFORE this happens.  And even if it never does, we have invested in some good water, infrastructure, land use and social planning for Oregon for what looks to be a more populous future.

“Down one road lies disaster, down the other utter catastrophe.” –Norman Church

I have quoted and echoed these thoughts here before: people living on the coastlines of the world are helping to create the damage and hardship that high-intensity coastal storms bring.  Before anyone claims that I’m blaming the victims here, let me articulate a subtler argument. As people and resources (ports, businesses, expensive homes, etc.) are concentrated on coast lines, storms can yield greater damage.  Seems like a simple argument, right?

Unfortunately, most of humanity is not heeding it: worldwide the proportion of people (rich and poor) living on the coastlines is increasing.  By mid-century, the world population is expected to be at least 80% concentrated on coastlines.  In the United States, according to National Oceanic and Atmospheric Administration and its document Population Trends Along the Coastal United States: 1980-2008,  the total number of people living on our coasts will grow by 7 million, up from 153 million as of 2003. That’s about 53% of the nation’s total population.

Regardless of whether storm intensity increases due to climate change, population increases and concentrations of wealth and economic resources on coast lines will mean bigger losses with each storm.

The on-line version of Time Magazine has a nice article on the subject with references to some of the harder literature backing up these claims.  Here is a quote from the article that makes up the crux of the issue:

“If climate change is having an effect on the intensities of storms, it’s not obvious in the historical weather data. And whatever effect it is having is much, much smaller than the effect of development along coastlines. In fact, if you look at all storms from 1900 to 2005 and imagine today’s populations on the coasts, as Roger Pielke Jr., and his colleagues did in a 2008 “Natural Hazards Review” paper, you would see that the worst hurricane would have actually happened in 1926.

If it happened today, the Great Miami storm would have caused from $140 billion to $157 billion in damages. (Hurricane Katrina, the costliest storm in U.S. history, caused $100 billion in losses.) “There has been no trend in the number or intensity of storms at landfall since 1900,” says Pielke, a professor of environmental studies at the University of Colorado. “The storms themselves haven’t changed.”

What’s changed is what we’ve put in storms’ way. Crowding together in coastal cities puts us at risk on a few levels. First, it is harder for us to evacuate before a storm because of gridlock. And in much of the developing world, people don’t get the kinds of early warnings that Americans get. So large migrant populations — usually living in flimsy housing — get flooded out year after year. That helps explain why Asia has repeatedly been the hardest hit area by disasters in recent years.

Secondly, even if we get everyone to safety, we still have more stuff in harm’s way than ever before. So each big hurricane costs more than the big one before it, even controlling for inflation.”

You can read the full article by going here. The Center for the Epidemology of Disasters, also has some useful data to show the trend.

I should note that the North Coast is not easily comparible in terms of shear population or rates of growth to places like Mumbai or Miami-Dade.  We have seen, however, an increasing trend towards establishing wealthy second home development in the region (thus increasing our potential for greater losses).  With a wave of new retirements within the Baby Boomers, we can expect to see more of this in the long-run.  Communities such as Tillamook and Warrenton have also extended their business development into floodplains and low-lying areas on estuaries (also increasing the potential for losses when high water comes).  What is the take-home lesson here? Coastal communities must think in terms of development that will make them more resilient in the face of storms and floods, not more vulnerable.  That means thinking about where we place development, how we manage the natural systems that protect us from the worst of storm damage, and ways to increase prepardeness among the incoming population.

Portland-based Ecotrust has done some interesting things in its history. The non-profit organization focuses on applied ecological economics. In other words, they are interested in researching, describing and applying knowledge of how people value nature and natural resources.

The logic is simple: if you want to protect, restore, or maintain X-ecological function or X-species or X-ecosystem, you find out how much people will pay for that or conversely, what it will cost society if we don’t pay for it up-front. If a species such as coho salmon goes extinct, what is the direct and indirect economic cost? Likewise, what are the costs associated with protecting their habitat, water quality, or even individual organisms.  And beyond the single species perspective, what services do native ecosystems provide? The obvious ones most everyone knows: food, fiber, medicine, aesthetics, and recreation. There are other, less obvious benefits: clean air, clean water, fertile soil, protection from floods, spiritual solace, etc.  What do these cost us? What are they worth to us? Do the costs and benefits equate or can we pay for the difference if we loose something? And even more important, how do we distribute those costs and benefits across society?

Back to my original intent with this post: I wanted to point out some useful resources that the organization offers, mainly in the form of mapping tools, but also some great reports that catalogue coastal and coastal temperate forest issues.  These are the Oregon Estuary Plan Bookand the Watershed Locator. Ecotrust has also produced some useful information on ocean fisheries and marine reserves, all on their on-line atlas site called Inforain.

And speaking of tools, if you are reading this blog and see something I should know about (and tell others about), please let me know via the comments function. H2ONCoast has been on-line since July 2007. If there is something that it can do for you, please let me know.

The back and forth continues in Oregon over whether to sell some of “Oregon’s Oil” to the thirsty masses elsewhere. Presented here are the responses of the Democrats in the State Senate.

SALEM – Members of the Senate Democratic caucus Tuesday raised concern over a Republican plan to sell Oregon’s water to other states. The plan was released as part of the Senate Republican caucus’s agenda for the 2009 session.

“While the complexities of this proposal have yet to be vetted, it seems doubtful that this is the sort of idea that Oregonians could get behind,” said Senate Majority Leader Richard Devlin (D-Tualatin). “Democrats in the legislature would prefer to store our water here at home before shipping it off to California.”

The Republican plan, which calls water “Oregon Oil,” suggests that 70 million acre feet of water a year is “wasted” when the flow of the Columbia reaches the Pacific Ocean. They suggest that this water is in excess of that needed for farms, fisheries, and hydroelectric power.

“First and foremost, while not closing our minds to long-term viable solutions for state funding, we are committed to ensuring that Oregonians and our agricultural community have the stable and sufficient water supply they need” said Senator Alan Bates (D-Ashland), chair of the Senate Committee on the Environment and Natural Resources. “We are in the middle of a state-wide water needs assessment and we will respond to those needs before we divert our water anywhere outside of Oregon. Senate Democrats have demonstrated leadership on this issue, and I’m confident that we will continue our record of smart and sensible water planning for our state.”

Democrats have a strong record of looking out for Oregon’s water needs. During the 2008 February Session, Senate Democrats in the legislature passed the Agricultural and Community Water Act, or ACWA, which expands options for developing a sufficient and sustainable water supply for Oregonians. Additionally, in 2007 Democrats passed the first broad state water study in recent history.

“Continuing our commitment to Oregon’s water needs for now and the future is a duty that we don’t take lightly,” said Devlin. “We’re not interested in the commoditization of a precious resource when our own water security is still an issue and priority to many Oregonians.”

I’m stealing liberally from my colleague Michael Campana’s Water Wired here.  An old friend argued to me once that all research is just stealing with citations, anyway. Yet, this topic was just too good to pass up, especially given my provenance as a Southwestern water geek now transplanted to the PNW.  Here’s the tale: long ago, in a galaxy far away, water managers in California tapped rivers far to the North of the state’s population bulges in the South and Central regions, built massive dams and aqueducts that dewatered whole valleys to fuel the booming megaregions.  Working with colleagues, water lawyers and politicos in seven states and two nations, they also successfully plumbed the mighty Colorado to supply over 30 million people with water.  The time was the early to mid-20th century and the “we can engineer a better future” mentality was riding high.  At the same time, a few water wonks speculated that the Columbia River–exceeding the Colorado’s flow by about 10 times–could play a role in future growth or drought scenarios. “Ridiculous!” many shouted, “that’s both unfeasible and unnecessary!”

Well, to quote Bob Dylan, “the times, they are a-changin’.”  It seems that some would quite seriously speculate that we’ve arrived in one one of those scenarios. As the reservoirs in the mighty Colorado dwindle under the weight of 8 years of serious drought (a good winter notwithstanding) and even more serious population growth, it seems that the basin’s states are contemplating just this sort of action (among others that include giant plastic-wrapped icebergs).  Searching for answers to the persistent question of “where will we get our water from,” managers are dredging up ideas that seem at face value to be technically impossible,  politically unfeasible, and economically unpalatable: extending a giant straw to the Colombia (likely inserted at–forgive the pun–the mouth) in order to send some precious water southward.

And Oregonians are contemplating what the water could cost and how we might facilitate selling it to them.  Think this is politically wild science fiction?  Sound like something out of Robert Ludlum meets Marc Riesner? Think again and read Michael Milstein’s piece in yesterday’s Oregonian. While you’re at it, check out the Aquadoc’s word on it too. And don’t forget to take a look at the press release put out by Oregon State Sen. David Nelson (R-Pendelton)  who proposes to sell 1 million acre-feet to out-of-state communities (read: the thirsty Southwest).  While this is still pretty speculative, the times they are a-changin’!

A couple of weeks ago I had the thrill of meeting the author of one of my college text books, Professor Emeritus of SUNY College of Environmental Science and Forestry, Syracuse, Peter Black. Pete wrote the classic textbook, Watershed Hydrology which was used by just about everyone I know in the field. It’s a basic but very thorough text for beginners in watershed management. I’ve seen it in many of my colleagues’ office libraries.  I can now say I’m a true water geek when I get a celebrety thrill from meeting people who write these kinds of things.

Pete has moved on from his days at SUNY but has not slowed down one bit. He’s been selling his now out-of-print texts, as well as a series of well-done PowerPoint presentations on watersheds and hydrology.  He’s got a great, no-frills website full of information for watershed and non-watershed wonks alike to be found at: www.watershedhydrology.com.  But most innovatively, he’s reached out to the public which so often doesn’t know what a watershed is, much less how the water in it might be influenced by their actions. Towards that end, Pete’s produced a wonderful set of broadcasts and now podcasts called “Water Drops” which to put in his terms, “celebrate the wonder of water.”  They appear on public radio station WRVO, FM in Syracuse, NY and are availble as podcasts at the station’s website. Go check ‘em out.

I just returned from the Universities Council on Water Resources (UCOWR) conference in Durham, NC. For water wonks like me, it was a fascinating confluence of people and ideas. One topic that consistently appeared on the agenda was ground water and its neglect by state, federal and local agencies.

Ground water is a neglected resource from both a quality and quantity perspective. Often, we don’t worry excessively about how much of it we can extract before the loss becomes apparent.  Collectively, we worry less about how usable the water is until something untoward happens (as in the case of groundwater contamination in Love Canal, NY, now 30 years ago and Hinkley, CA, the setting for Erin Brockovich’s famous tale of chromium contamination).  Worse yet, while municipalities that depend upon it map and measure both quantity and quality, well owners are generally left in the dark between establishing a well and selling their land.  And that’s just the case in only slightly more regulated environment of Oregon.

At the same time, the US Geological Survey has just published a report that maps the ground water of the United States.  Below is the abstract. You can access the full report by visiting this link.  In Oregon, some interesting events will come up this fall/winter regarding ground water and wells. Stay tuned to H2ONC for more information.

Ground water is among the Nation’s most important natural resources. It provides half our drinking water and is essential to the vitality of agriculture and industry, as well as to the health of rivers, wetlands, and estuaries throughout the country. Large-scale development of ground-water resources with accompanying declines in ground-water levels and other effects of pumping has led to concerns about the future availability of ground water to meet domestic, agricultural, industrial, and environmental needs. The challenges in determining ground-water availability are many. This report examines what is known about the Nation’s ground-water availability and outlines a program of study by the U.S. Geological Survey Ground-Water Resources Program to improve our understanding of ground-water availability in major aquifers across the Nation. The approach is designed to provide useful regional information for State and local agencies who manage ground-water resources, while providing the building blocks for a national assessment. The report is written for a wide audience interested or involved in the management, protection, and sustainable use of the Nation’s water resources. http://pubs.usgs.gov/circ/1323/

The following is reprinted from my recent article in the Tillamook County Headlight Herald.

Looking across a pasture, lawn or garden, any farmer or gardener can you tell you about weeds. Weeds are unwanted plants, generally because they grow in places we don’t want them to occupy. But often, these plants can be a much graver threat to our human and naturally-managed landscapes. Instead of just weeds, we refer to them as invasive plants. Examples include Himalayan blackberry, knotweed, cheat grass, and English ivy.

Invasive plants are those that are so successful that they grow to the exclusion of most or even all others. It’s not just plants that can become invasive; some species of animals have become invasive on virtually all continents. Some famous examples include rabbits in Australia, Norway rats, gypsy moths and Africanized honeybees in the United States, and the mongoose in the South Pacific islands. Another famous example is the pairing of the non-native Asian tiger mosquito with the West Nile virus in North America.

Invasive species of plants and animals overcome geographic barriers—often by hitchhiking with humans, cargo, or domesticated animals—into new habitats. In these new habitats, they have few or none of their natural enemies and quickly take over.

The invasion of unwanted plants and animals into new habitats is one of the most important challenges of our times. Invasive species cost Americans alone an estimated $138 billion a year in control, prevention and direct economic losses. Next to the immediate loss of habitat, invasive species are the second largest threat to native plants and wildlife world wide.

Gardening to Eliminate Invaders

Gardens and gardeners are one of the most important pathways for invasive plants to move into new places. You can help stop the biological invasion by eliminating known invasive plants from your garden, preventing the introduction of new, aggressive plants, and replacing non-native invaders with friendly native plants.

Some common plants to avoid include: English or Irish ivies (Hedera helix or H. hibernica), butterfly bush (Buddleia davidii), knotweed (Fallopia spp.), bachelor’s buttons (Centaurea cyanus), purple loosestrife (Lythrum salicaria), money plant (Lunaria annua), spreading bamboos, yellow flag iris (Iris pseudocorus), chameleon plant (Houttuynia cordata), French, Scotch, Spanish, or Portugese brooms, English holly (Ilex aquifolium), spurge laurel (Daphne laureola) , Jubata grass (Cortaderia jubata), leafy or myrtle spurge (Euphorbia esula or E. myrsinites) , and old man’s beard (Clematis vitalba). You can find some excellent replacements for these plants by picking up a copy of a new booklet titled, “GardenSmart Oregon: A Guide to Non-Invasive Plants” at the OSU Extension Service office or by going to www.oregoninvasiveshotline.org for an on-line version. Thanks to support from many corporate and public sponsors, the guide is free.

Volunteering to Map the Invasion

One of the key issues with invasive species is that once they get started in a new location, it can be difficult if not impossible to completely remove them. One of my colleagues at Oregon State University likes to say, “If you don’t catch them early, biological invasions are forever!” Like a wildfire, invasive species start out as small patches of a few organisms, and then when conditions are right, spread rapidly across the landscape. So it is important to identify and locate the invaders before they get a toe-hold. Once they are established, it is best to know the direction and spread of the invasion.

That is why the Tillamook Estuaries Partnership, Oregon Sea Grant Extension and The Nature Conservancy are piloting a new program to train citizens to spot invasive plants and animals before they get out of control, as well as to map the extent of invasions already underway. The Tillamook Invasive Species Early Detection Program will be a model for others across Oregon.

Thirty local volunteers will be trained to identify and map invasive species on publicly-managed lands in Tillamook County. The all-day, intensive training will take place on August 1st from 9:30 AM to 3:30 PM at the Oregon Department of Forestry, Tillamook District office conference room (5005 3rd Street, Tillamook) and at a selected field site. Participants will learn about biological invasions, learn to identify some important examples, and spend some time in the field looking for them. The training is free. To register, please call Pat Penney at the OSU Extension Service; (503) 842-3433.

To warm up for the training, the Tillamook Estuaries Partnership will sponsor a free presentation on aquatic invasive species by Oregon Sea Grant’s Dr. Samuel Chan. This open-to-the-public event will take place at the Oregon Department of Forestry, Tillamook District office conference room on Wednesday, July 30th, from 6:00-8:00 PM. For more information, contact TEP; (503) 322-2222.

There’s a gorgeous, large yellow iris called “yellow flag” or “yellow water iris” (Iris pseudacorus) found in wetlands, along riverbanks and near ponds in Oregon. It is sold in local nurseries and garden stores as well.

But there’s a big problem with this lovely perennial iris. It is invasive and out-competes native riparian vegetation, including cattails, sedges and rushes, and it degrades native fish habitat, as well as bird nesting and rearing sites. Native to Europe, Great Britain, North Africa and the Mediterranean region, yellow flag iris has been introduced in temperate areas nearly worldwide and occurs throughout the United States except in the Rocky Mountains. It appears to be most common near developed areas.

You wouldn’t expect widely available, familiar plants like yellow flag iris to be out-of-control noxious weeds. But yellow flag iris, native to Europe, has escaped cultivation and moved into rivers of the Pacific Northwest.

With large showy yellow blossoms, yellow flag, also known as water flag, can grow in large clumps and has been know to reduce the carrying capacity of wetlands for water storage, and block irrigation canal flow and flood control ditches. Difficult to eradicate, it is common in mid-Willamette Valley riparian areas and has been found along rivers in central Oregon.

“If you see a yellow-flowered iris growing directly in water in Oregon, it is most likely yellow flag,” said Andy Hulting, a weed specialist with the Oregon State University Extension Service.

In Oregon, yellow flag blooms in late spring or early summer. Several flowers can occur on each stem, along with one or two leafy bracts. Each flower resembles a common garden iris with three large (1.5- to 3-inch) downward facing yellow sepals and three smaller upward pointing petals. The yellow sepals are often streaked with brown to purple lines. Flower color ranges from cream to bright yellow. Some horticultural varieties have been developed with variegated leaf color. The plants may grow to almost five feet in height. The leaves are mostly basal and are folded and clasp the stem at the base in a fan-like fashion.

A perennial, yellow flag iris will remain green during the winter where the weather is mild, but leaves will die back during periods of prolonged drought or below-freezing temperatures. It spreads both by seed and by stout underground stems called rhizomes from which its roots can grow to a foot in length.

After flowering, the large seed capsules of yellow iris are up to 2.5 inches long and contain many dark to reddish-brown seeds. When not flowering, yellow flag iris may be confused with cattail (Typha latifolia) or broad-fruited bur-reed (Sparganium eurycarpum). Look for the fruits in the summer, or the fan-shaped plant-base at other times of year.

Up to several hundred flowering plants may be connected by rhizomes. Fragments of rhizome can form new plants if they break off and drift to suitable habitat. The flowers are pollinated by bumblebees and long-tongued flies. Seeds germinate and grow well after being burned in late summer. Yellow flag readily resprouts from rhizomes after burning.

As a popular ornamental plant for wet areas or well-mulched soil, yellow flag is widely sold in nurseries and on the Web. It has often been planted in wastewater or storm water treatment ponds, been used to control erosion and is known to take up metals and nutrients in wastewater treatment facilities. It is a popular garden plant for wet or well-mulched soil, and has been introduced as an ornamental throughout the world.

“Yellow flag is being widely distributed by water garden enthusiasts,” said Hulting. “This likely leads to unintentional releases in urban and suburban wetlands and eventually wetlands across the landscape, spread by seed and rhizome fragments during high water events. We’d like to help gardeners become more aware of the ecological effects invasive plants like yellow iris might have on the environment.”

The best control is prevention, said Hulting. “Learn to identify it and don’t plant it. Encourage other gardeners not to plant it.”

Yellow flag is listed on the Oregon Department of Agriculture’s Noxious B list, meaning it is locally invasive and not yet widespread. The Pacific Northwest Exotic Pest Plant Council lists it as ‘A-2 Most Invasive-Regional’ (highly to moderately invasive but still with a potential to spread).

The OSU Extension Service recommends the following wetland native plants as being more ecologically appropriate alternatives to yellow flag: monkey flower, Rocky Mountain iris, Douglas iris and skunk cabbage. Also, these non-native ornamentals are less invasive: Japanese iris, Siberian iris and blue flag.

To help home gardeners and landscape designers make sound ecological choices about what to plant in their gardens, the Oregon State University Extension Service has published a 52-page booklet called GardenSmart Oregon (EC 1620), in cooperation with City of Portland, The Nature Conservancy, Oregon Association of Nurseries, Clackamas Community College, Oregon Public Broadcasting, OSU Extension Service and OSU Sea Grant. GardenSmart Oregon is available online at: http://extension.oregonstate.edu/catalog/pdf/ec/ec1620.pdf

Or, call 1-800-561-6719 to request a printed copy of GardenSmart Oregon ($3 per copy shipping and handling fee). Local county offices of the OSU Extension Service have copies available for no charge.
http://extension.oregonstate.edu/locations.php

Pulling can control isolated plants of yellow flag iris or digging, but use care and protect your skin as resins in the leaves and rhizomes can cause irritation. Because rhizome fragments can grow to form new plants, be sure to clean up all fragments. Large-scale tillage to control yellow flag should be avoided because of the likelihood of spreading rhizome fragments, warned Hulting.

“Limiting soil disturbance can help native plants survive and make the site more resilient to reinvasion by yellow flag,” he said.

If you can do nothing else, remove and destroy the seed heads and flowers of yellow flag, he advised.

Large-scale infestations of yellow flag most likely need to be managed by chemical means to achieve complete control and limit the spread. Formulations of glyphosate labeled for aquatic uses (examples: Rodeo or Aquamaster) have been effective on yellow flag iris when applied as a spot treatment. Take care to not overspray onto desirable plants when making glyphosate applications. Follow the mixing directions and application instructions on each label.

“Cut stump” treatments, or cutting or mowing foliage and applying glyphosate directly to the cut surface of individual plants have also been effective for managing smaller infestations of yellow flag iris and can negate herbicide injury to non-target plants. Because this plant is a rhizomatous perennial multiple applications over multiple years will likely be needed for complete control, said Hulting.

No biological control organisms have been approved for yellow flag iris.

Residents of Tillamook County, OR should have some serious empathy for those in the flood-ravaged Midwest. After all, we’ve had two record floods two years in a row. But there are some lessons to be learned from the case of Iowa as the following story from Joel Achenbach of the Washington Post (June 19 edition) points out. While the picture is—forgive the pun—muddy, the modification of the landscape in Iowa and the entire Midwest may be exacerbating the capacity of the region’s streams to hold, release and convey water during extreme rainfall events. H2ONC certainly agrees with that assessment and points to large-scale landscape modification in our own basins as reason to take heed of lessons from Iowa.

As the Cedar River rose higher and higher, and as he stacked sandbags along the levee protecting downtown Cedar Falls, Kamyar Enshayan, a college professor and City Council member, kept asking himself the same question: “What is going on?”

The river would eventually rise six feet higher than any flood on record. Farther downstream, in Cedar Rapids, the river would break the record by more than 11 feet.

Enshayan, director of an environmental center at the University of Northern Iowa, suspects that this natural disaster wasn’t really all that natural. He points out that the heavy rains fell on a landscape radically reengineered by humans. Plowed fields have replaced tallgrass prairies. Fields have been meticulously drained with underground pipes. Streams and creeks have been straightened. Most of the wetlands are gone. Flood plains have been filled and developed.

“We’ve done numerous things to the landscape that took away these water-absorbing functions,” he said. “Agriculture must respect the limits of nature.”

Officials are still trying to understand all the factors that contributed to Iowa’s flooding, and not everyone has the same suspicions as Enshayan. For them, the cause was obvious: It rained buckets and buckets for days on end. They say the changes in land use were lesser factors in what was really just a case of meteorological bad luck.

But some Iowans who study the environment suspect that changes in the land, both recently and over the past century or so, have made Iowa’s terrain not only highly profitable but also highly vulnerable to flooding. They know it’s a hard case to prove, but they hope to get Iowans thinking about how to reduce the chances of a repeat calamity.

“I sense that the flooding is not the result of a 500-year event,” said Jerry DeWitt, director of the Leopold Center for Sustainable Agriculture at Iowa State University. “We’re farming closer to creeks, farming closer to rivers. Without adequate buffer strips, the water moves rapidly from the field directly to the surface water.”

Corn alone will cover more than a third of the state’s land surface this year. The ethanol boom that began two years ago encouraged still more cultivation.

Between 2007 and 2008, farmers took 106,000 acres of Iowa land out of the Conservation Reserve Program, which pays farmers to keep farmland uncultivated, according to Lyle Asell, a special assistant for agriculture and environment with the state’s Department of Natural Resources (DNR). That land, if left untouched, probably would have been covered with perennial grasses with deep roots that help absorb water.

The basic hydrology of Iowa has been changed since the coming of the plow. By the early 20th century, farmers had installed drainage pipes under the surface to lower the water table and keep water from pooling in what otherwise could be valuable farmland. More of this drainage “tiling” has been added in recent years. The direct effect is that water moves quickly from the farmland to the streams and rivers.

“We’ve lost 90 percent of our wetlands,” said Mary Skopec, who monitors water quality for the Iowa DNR.

Crop rotation may also play a subtle role in the flooding. Farmers who may have once grown a number of crops are now likely to stick to just corn and soybeans — annual plants that don’t put down deep roots.

Another potential factor: sediment. “We’re actually seeing rivers filling up with sediment, so the capacity of the rivers has changed,” Asell said. He said that in the 1980s and 1990s, Iowa led the nation in flood damage year after year.

This landscape wasn’t ready for the kind of deluge that hit Iowa in May and early June. Central and eastern portions of the state received 15 inches of rain. That came on top of previous rains that had left the soil saturated. Worse, the rain came at the tail end of an unusually cool spring. Farmers had delayed planting their crops. The deluge struck a nearly naked landscape of small plants and black dirt.

“With that volume of rain, you’re going to have flooding. There’s just no way around it,” said Donna Dubberke, a meteorologist with the National Weather Service in the Quad Cities. “This is not just because someone put in a parking lot.”

The rising Mississippi River is expected to peak this week, threatening towns and farmland north of St. Louis as floodwaters continue to move down the river. So far, flooding and severe weather have killed at least 24 people in three states and injured 106, forced the evacuations of about 40,000, and driven corn prices to record highs.

Two levees burst just north of Quincy, Ill., yesterday morning, forcing the evacuation of the small town of Meyer. Yesterday afternoon, Illinois Gov. Rod Blagojevich (D) visited the town after viewing the nearby Sny Island Levee, about 12 miles downstream from Quincy and, at 54 miles long, the second-biggest levee on the Mississippi.

In Iowa, the National Weather Service has reported record flooding at 12 locations on four rivers, including the Cedar, the Iowa, the Wapsipinicon and the Mississippi. The U.S. Geological Survey has preliminary data showing 500-year floods on the Cedar, the Shell Rock, the Upper Iowa and the Nodaway.

The Great Flood of 2008 has, for many inhabitants of sandbagged Iowa, come awfully soon after the Great Flood of 1993. Or, as Elwynn Taylor, a meteorologist at Iowa State University, put it: “Why should we have two 500-year floods within 15 years?”

Taylor attributes the flooding in recent years to cyclical climate change: The entire Midwest, he says, has been in a wet cycle for the past 30 years.

There has also been speculation that global warming could be a factor.

“Something in the system has changed,” said Pete Kollasch, a remote-sensing analyst with the Iowa DNR. “The only thing I can point my finger at is global warming, but there’s no proof of that.”

Jeri Neal, a program leader for ecological systems and research at Iowa State’s Leopold Center, said all these things have a cumulative effect on the landscape: “It doesn’t have the resilience built into it that you need to withstand disturbances in the system.”

The idea of a 500-year flood can be confusing. Hydrologists use the term to indicate a flooding event that they believe has a 0.2 percent chance — 1 in 500 — of happening in any given year in a specific location. A 100-year flood has a 1 in 100 chance of happening, and so on. Such estimates are based on many years of data collection, in some cases going back a century or more.

But the database can be spotty. Robert Holmes, national flood coordinator with the U.S. Geological Survey, said a lack of funding since 1999 has forced his agency to discontinue hundreds of stream gauges across the country. “It’s not sexy to fund stream flow gauges,” he said.

What’s certain is that a lot of water had nowhere to go when the sky opened over Iowa this spring. Some rivers did things they’d never done before. The flood stage at Cedar Rapids, for example, is 12 feet. The previous record flood happened in 1929, when the Cedar hit 20 feet. This year the Cedar hit 20 feet and kept rising. Experts predicted it would crest at 22 feet, and then upped the estimate to 24 feet. The river had other ideas. At mid-morning last Friday, it finally crested at 31.3 feet.

The entire downtown was flooded and a railroad bridge collapsed, dumping rail cars filled with rock into the river.

“Cities routinely build in the flood plain,” Enshayan said. “That’s not an act of God; that’s an act of City Council.”

Staff writer Kari Lydersen contributed to this report from Quincy, Ill.