Tag Archives: floodplain

The Science Behind Colorado’s Catastrophic Floods

colorado-national guard

Photo credit: Colorado National Guard.

Just a few months ago, Boulder, Colorado was in the grip of yet another drought, reports TIME magazine online, and the state also experienced its worst wildfire on record earlier this year. But after days of heavy rainfall that the National Weather Service called “biblical,” drought and fire are the last things that Boulder and the rest of the northern Front Range of Colorado has to worry about. The more lasting effects will be caused by the catastrophic flood events that have ravaged portions of the state over the last few weeks.

With weather extremes becoming more common, it is more important than ever to be sure we encourage resilient landscapes. Healthy, functioning floodplains and wetlands can protect freshwater resources, and infrastructure from the extremes of drought and flood.

Andrew Freedman of Climate Central described the climate factors contributing to the Colorado floods: “An increase in the frequency and intensity of extreme precipitation events is expected to take place even though annual precipitation amounts are projected to decrease in the Southwest…That may translate into more frequent, sharp swings between drought and flood, as has recently been the case.”

Many experts agree that climate-change-related severe weather events all around the country are here to stay.  Fires due to drought will, in turn, exacerbate flooding due to fire-exposed soils, and fire-damaged vegetation. Protection and restoration of fire-damaged areas, floodplains, and wetlands can help protect both life and property.

Read more: http://science.time.com/2013/09/17/the-science-behind-colorados-thousand-year-flood/#ixzz2fS83Pfy9

You may also like: Wildfire and Water: Post-Fire Assessments Provide Quick Answers, and Know Your Risk: Floodwaters Can Transform Small Streams into Raging Rivers

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Flooding and Floodrisks Defined at FloodSmart.gov

Anywhere it rains, it can flood. Many conditions can result in a flood: hurricanes , overtopped levees, outdated or clogged drainage systems and rapid accumulation of rainfall.

Just because you haven’t experienced a flood in the past, doesn’t mean you won’t in the future. Flood risk isn’t just based on history, it’s also based on a number of factors: rainfall, river-flow and tidal-surges, topography, flood-control measures, and changes due to building and development.

FloodSmart.gov provides flood-hazard maps to show different degrees of risk for your community, which help determine the cost of flood insurance.  We suggest you check  these maps annually as they do change.

Trout Headwaters advocates for, and works to restore healthy functioning floodplains, which can slow and filter floodwaters, reducing flood damage.  You may want to read our recent article: “Know Your Risk: Floodwaters Can Transform Small Streams into Raging Rivers,” and call our offices if you own, or are thinking of investing in, streamside or river front property.

Read more: http://www.floodsmart.gov/floodsmart/pages/flooding_flood_risks/ffr_overview.jsp

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Know Your Risk: Floodwaters Can Transform Small Streams into Raging Rivers

Montana floodwaters

photo courtesy of Montana DNRC

All streams and rivers are subject to flooding.  In mountainous areas, it’s typically annual spring flooding.  But other regions experience heavy rain events at other times of the year that can very quickly turn a peaceful stream into a raging torrent.  At THI we often help prospective landowners determine if buildings are in jeopardy, or help landowners make decisions about where to site homes and other improvements.

Before you build in or very near a floodplain, please consider the following: A stream or river is constantly adjusting itself. This is nature’s balancing act between the amount of water and gradient in the channel, and the amount and size of the sediment within the system. Any disturbance, either natural or human-caused, will change this balance. Activities such as building within the floodplain, constructing roads in riparian areas, or removing vegetation can limit a stream’s ability to maintain a healthy balance.

Residential or commercial construction within the floodplain does have an impact, as does protecting property by constructing dikes, levees, installing riprap, or eliminating overflows into side channels. The effects of these impacts within the floodplain can include increased peak flood levels, increased energy during a flood event downstream, increased bank and bed erosion on neighboring property, reduced habitat and reduced recreational values.

To limit or eliminate these impacts, avoid construction in the floodplain where possible; do not restrict floodwater access to side channels; and ensure construction within the floodplain minimizes disturbance of soils and vegetation.  Contact THI to Learn More or Request a Free Report Titled: Building Near Streams or Rivers.

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What Your Stream Assessment Report Should Tell You

Assessment and MonitoringIt’s impossible to know where you are going without understanding where you stand right now. Unfortunately, in the relatively new industry of stream, river and wetland restoration, there are individuals and companies making recommendations, and even performing work, without properly evaluating the current condition of the resource.

Baseline assessment can best be described as the basis by which to judge the success of any action taken to conserve, protect, enhance or restore water resources.  Monitoring is performed on a regular basis following implemented management changes and/or treatments to continue to measure the health of the resource.

THI performs baseline assessments to meet a variety of objectives, and to guide all restoration planning, design and installation. New technologies have made the assessment process relatively quick and low-cost – certainly the best investment toward a successful enhancement or restoration project.

 Assessments are used to:

  • Provide baseline data for permitting or for comparison over time;
  • Determine the ecological health of a stream, river or wetland system;
  • Reveal ecological potential;
  • Answer project feasibility questions;
  • Uncover hidden problems before you build (or before you buy);
  • Add value to due diligence;
  • Prevent costly surprises.

To learn more or receive our free Assessment and Monitoring Fact Sheet contact Trout Headwaters today.

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Bringing Back the San Joaquin Valley Floodplain

Healthy floodplains are nature’s buffer against weather extremes. The San Francisco Chronicle reports on an innovative project  in the San Joaquin Valley  combining  flood management with ecosystem restoration.  The plan includes the purchase of an existing ranch by a nonprofit group called River Partners. The $10 million project is expected to take 10 years to complete, and will transform low-lying farmland back into riparian floodplain.

John Carlon, president of River Partners, quoted in the Chronicle said, “A really major component of this project is flood control.  If all these low areas near the river were acquired, theoretically you could store more water in the reservoirs because you could spill more out all at once without hurting the neighbors. It is a different way of looking at water supply management.”

Reclaiming almond groves, corn and wheat fields and retuning them to wetlands will benefits migrating fish as well as hundreds of thousands of birds along the Pacific Flyway, one of the largest migratory bird paths in the world.

According to the Chronicle, some 95 percent of the historic floodplains in the Central Valley were filled in or blocked by levees after the Gold Rush. The work is a model for California’s first-ever attempt to create a systemwide flood management plan for the state’s major reservoirs.

Read more: http://www.sfgate.com/science/article/San-Joaquin-Valley-floodplain-coaxed-back-4194095.php

 

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Op-Ed: Restoring waterways is crucial

The cleanup of the Bronx River helped blunt the impact of Hurricane Sandy write JOSÉ SERRANO AND JOHN F. CALVELLI in Crain’s (http://www.crainsnewyork.com)

The tristate area is only beginning to recover from the destruction wrought by Hurricane Sandy.  As we assess the damage and how we prepare for a future storm, it is worth noting that work by local communities, government and nonprofit groups to restore and stabilize the city’s local waterways may well be part of the answer.

Nowhere is this better typified than in the tremendous strides that have been taken to restore the Bronx River. Neglected for much of the 20th century, it is now a national model for reclaiming urban rivers, thanks to a joint effort of the federal government, the Bronx Zoo and dedicated local groups…
…The restoration of the floodplains in the lower Bronx River and the reconstruction of riparian habitat along the rest of the river helped to blunt the impact of the storm in nearby neighborhoods…

…Wetland restoration projects in the Bronx, Jamaica Bay and Jersey City seem to have survived Sandy with minimal damage. Mayor Michael Bloomberg‘s PlaNYC wisely commits upwards of 1.5 billion dollars in the next two decades to natural, or “green,” infrastructure.

Read more: http://www.crainsnewyork.com/article/20130111/OPINION/130119984#ixzz2HzW0UNZQ

Read Also: NWF Offers 10 Important Tips for Working with Nature to Keep Us Safe

 

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Researcher: Stream Repairs in Vermont post-Irene “Ad-Hoc and Willy-Nilly”

For a stream scientist Tropical Storm Irene, which dumped loads of rain on Northeast, provided what one researcher calls a “grand experiment” — the opportunity to investigate what happens when a stream system faces a major disturbance.
In Vermont, where Dartmouth College scientists are studying the aftermath, the storm knocked out hundreds of roads and bridges in the state, damaged or destroyed more than 700 homes and left some towns stranded. Flooding moved whole sections of rivers and streams, gouging out roads and farm fields. In some cases, huge piles of gravel were deposited in other locations.
“Irene was a wakeup call,” said Dartmouth geography professor Frank Magiligan.  Magiligan and others are assessing streams in order to pinpoint potential trouble spots that can aid scientifically-informed planning decisions.  But recovery and repair efforts are concerning to some scientists, who say efforts to “repair and restore” streams with bulldozers and other heavy equipment actually “did more damage that the storm.”

Read more:  http://www.huffingtonpost.com/2013/01/14/tropical-storm-irene-damage-vermont-dartmouth_n_2471501.html

 

 

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Sierra Club Works to Save the Eastern Cottonwood

Clark explored the Yellowstone River in a boat made of lashed cottonwood trees. These trees, which grow along many plains rivers, proved invaluable throughout the journey, providing shade and shelter as well as transportation. To commemorate the tree, Clark named the site where he constructed the boats Camp Cottonwood. But the massive groves have been dying out because of dams, which block the seasonal flooding of the riverbanks. Cottonwoods, both this species and black cottonwood, Populus trichocarpa, which occurs further west, require the rich silt deposited by high springtime water in order to germinate. Since dams have altered the rivers’ flow, no new trees are taking root to replace the old ones. Along the Garrison Reach of the Missouri River, the Sierra Club is planting cottonwoods and working to restore the river to its natural flow patterns.

Read more: http://www.sierraclub.org/lewisandclark/species/easterncottonwood.asp

 

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Assessing Your Flood Risk

With unpredictable weather patterns becoming the new normal, it may be time to take a fresh look at the flood risk for your home or business.   At THI we often work with clients who have concerns about potential flood risks.  Streams, rivers and wetlands do flood, and it’s much more cost-effective to take time to understand and mitigate flood risks prior to a flood emergency, than to have to make those decisions under immense time pressure.

Your local emergency management office will have detailed records on severe weather and flood activity for your area. FloodSmart.gov, the official site of the National Flood Insurance Program is a good place to start.  Historical data on flood levels are helpful, since past events usually fall into patterns, and past flood levels will give an indication of what kind of water levels could be possible.  However, the last decade has seen extreme flooding and extreme droughts in unusual patterns, so it’s important to re-evaluate your flood risks based on these conditions.

If your home or other structure located in or near a floodplain, it’s important to take steps to mitigate flood risks now.  We always recommend to our clients to site buildings and other infrastructure well beyond the designated 100-year floodplain. For more information read: For Builders, Architects, and Homeowners – Building Near a River or Stream?

 

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Engineering Cannot Save Our Rivers

We note the draft language in Montana DNRC’s 2012 Model Floodplain Ordinance requiring that “a licensed professional engineer” (P.E.) design all stream restoration and bank stabilization projects undertaken in Montana.  While engineering is an important professional discipline, the proposed rule as written would greatly diminish the vital roles played by hydrologists, fluvial geomorphologists, sedimentologists, ecologists, and the other skilled scientists in this important work.  Further, it’s very important to understand that there is no consistent requirement in a professional engineer’s academic training or in Montana’s P.E. certification criteria that would dictate the attainment of specific skills for stream bank stabilization and restoration.

Decades of misguided, hard-engineering attempts to force natural stream systems into unnatural configurations have resulted in unhealthy, armored floodplains along many of our nation’s streams, including in Montana.  History will likely describe our time as a period of human failure – the failure to understand and the failure to accommodate the most basic ecological needs and functions of our precious water resources. These waters and their floodplains serve a broad host of ecological services for humans and wildlife, providing biodiversity, aquifer recharge and carbon sequestration. Without the protection of these basic functions, we will pass to the next generation a tarnished legacy of damaged and destroyed resources.

Any successful stream restoration or bank stabilization project requires a multi-disciplinary or inter-disciplinary team of scientists and technicians to ensure success. THI would suggest that granting a design monopoly for stream bank stabilization and river restoration to engineers may simply expose many P.E.’s to increased liability due to a general lack of direct experience in these applications.

Anyone interested in the future of Montana’s Floodplains, Rivers and Wetlands should comment on Montana DNRC’s 2012 Model Floodplain Ordinance now:  Traci Sears phone: 406-444‐6654, or via email  at  tsears@mt.gov

>>Read the Montana DNRC’s 2012 Model Floodplain Ordinance http://dnrc.mt.gov/wrd/water_op/floodplain/news/draft_model_ordinance.pdf

 

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