Researchers at the University of Minnesota have developed a unique new computer model called the Virtual StreamLab, designed to help restore real streams to a healthier state. The Virtual StreamLab, which demonstrates the physics of natural water flows at an unprecedented level of detail and realism, was unveiled for the first time this week at the 2009 American Physical Society Division of Fluid Dynamics meeting in Minneapolis, one of the largest conferences in fluid dynamics with more than 1,500 attendees from around the world. The University of Minnesota team of researchers led by civil engineering professor Fotis Sotiropoulos, director of the University’s St. Anthony Falls Laboratory (SAFL), developed the Virtual StreamLab to help improve stream restoration processes. They have completed their first simulation of SAFL’s Outdoor StreamLab, a scaled natural stream along the Mississippi River. More than 90 million data points have been mapped into the team’s computer model resulting in the most accurate model of a real stream to date. The Virtual StreamLab employs sophisticated numerical algorithms that can handle the arbitrarily complex geometry of natural waterways, features advanced turbulence models, and utilizes the latest advances in massively parallel supercomputers.
The ability to simulate water flow over topography with this degree of realism provides researchers with the insights necessary to improve sustainable stream restoration strategies, helping to optimize techniques to fight erosion, help prevent flooding and restore aquatic habitats in degraded waterways.
Recent national data shows that 44 percent of the nation’s 3.5 million miles of rivers and streams have become degraded due to sedimentation and excess nutrients. This decline has led to impaired water quality over entire watersheds, rendering many streams unhealthy for recreation and public contact. The effects also have serious consequences for the health of aquatic life. Efforts to restore these bodies of water have resulted in an annual cost of more than $1 billion in the United States alone.
Historically, efforts have involved installing structures in the stream to change the direction and speed of the water, but with little ability to fine-tune a stream’s reactions. Past computer models often oversimplify the stream systems and can’t accurately simulate the beds, complicated bank shapes, turbulence, and natural or man-made structures within them.
“The practice of stream restoration has had a rocky rate of success as practitioners have struggled to alter a natural system with countless unknowns,” Sotiropoulos said. “The need for more effective and reliable stream restoration strategies is clear, but the underlying physical processes which govern the behavior of a stream and its inhabitants are very complex. Our new Virtual StreamLab should provide researchers with a deeper understanding of those complexities.”
Published: Tuesday, November 24, 2009 – 18:07 in Earth & Climate
NEW YORK, New York, February 2, 2009 (ENS) – It’s hard to imagine standing in midtown Manhattan, but wetlands do exist within New York City, and they both protect the city and need protection themselves, according to a report released Friday by Mayor Michael Bloomberg.
A man-made extended detention basin in the Staten Island Bluebelt after one growing season.
“Many New Yorkers don’t realize there are thousands of acres of wetlands in the five boroughs,” said Mayor Bloomberg. “Wetlands are robust ecosystems that perform crucial environmental functions like trapping pollutants, capturing stormwater runoff, sequestering carbon dioxide, and moderating storm surges.”
Today, the city has only one percent of its historic freshwater wetlands and 10 percent of its historic tidal wetlands.
These tidal remaining wetlands are concentrated in Brooklyn around Jamaica Bay, in Queens, and in Staten Island, which also has freshwater wetlands.
Freshwater wetlands smaller than 12.4 acres are not protected by state law and are vulnerable to determinations that they are outside of the scope of federal protection.
The new report shows that the extent of these smaller wetlands in New York City is not fully known.
To gather more information on the smaller freshwater wetlands, the report recommends developing new high-resolution aerial and satellite wetland maps to precisely determine the size and location of unprotected wetlands before pursuing other options outlined in the report. This mapping is scheduled to start later this year.
“In PlaNYC, we promised to study wetlands and build on wetland successes like the impressive Staten Island Bluebelt stormwater project managed by the Department of Environmental Protection, as well as the thousands of acres of wetlands managed by the Parks Department,” said the mayor.
The Staten Island Bluebelt is an award winning, ecologically sound and cost-effective stormwater management for about one third of Staten Island’s land area. The program preserves natural drainage corridors, including streams, ponds, and other wetland areas, saving tens of millions of dollars in infrastructure costs when compared to providing conventional storm sewers for the same land area.
“The critical role that wetlands play in the Staten Island Bluebelt system demonstrates the ability of wetlands to improve water quality by removing nutrients, waste, and sediment from stormwater runoff,” the report states.
The study also identifies threats to wetlands that are not from a lack of regulatory protection, but rather from the existing polluted or degraded condition of wetlands that may have been caused by rising sea levels and stormwater runoff.
In addition, submerged lands policy will be more important as sea levels rise in response to climate change. While open waters are subject to extensive state and federal regulatory protections, the city lacks a comprehensive submerged lands management policy.
To address these threats, the city’s Climate Adaptation Task Force will release a report on policies for the adaptation of wetlands and other critical infrastructure later this year.
The city is also exploring alternative funding, mitigation banking and other mechanisms for improved restoration and maintenance of wetlands.
New York City and other municipalities in the state can request that the state designate any remaining wetlands below 12.4 acres to be of “unusual local importance” and thus within state protection.
Recent decisions by the U.S. Supreme Court have weakened the protection of “isolated” wetlands. As a result, the report suggests that the city conduct a thorough study of the hydrological and ecological connection between wetlands and U.S. navigable waters that are clearly covered by the Clean Water Act, to bring those areas more clearly within the jurisdiction of federal regulators.
The city could impose zoning overlay districts on private wetlands or buffer areas or both, and possibly extend that protection to near shore and other underwater lands.
The report suggests that the city could create a local wetland regulatory permitting scheme that would protect smaller freshwater wetlands below 12.4 acres, or buffer areas, or both.
Finally, the report suggests that the city could allocate more resources to the restoration or management of city-owned wetlands and acquire more privately-owned wetlands.
Click here to view the report, which fulfills one of the 127 commitments in Mayor Bloomberg’s PlaNYC.
Copyright Environment News Service (ENS) 2009. All rights reserved.