Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Preservation of floodplains is flood protection

27.09.2017

The silting of rivers and streams leads to problems for fish, mussels, and other aquatic organisms because their habitats disappear. However, not only intensive agriculture and erosion are destroying these habitats. Now a study conducted by researchers at the Technical University of Munich (TUM) refutes this wide-spread view. In order to save the species living in the river basin – and protect people from the threat of devastating floods – rivers need more space, diversity, and freedom.

The subject of the study was the Moosach, a tributary of the Isar and located right at the Weihenstephaner “doorstep” of the TUM. The Moosach largely flows between the Munich gravel plain and tertiary hill country in an artificial bed. Every few years the river has to be excavated to remove several thousand cubic meters of mud.


The silting of rivers and streams leads to problems for fish, mussels, and other aquatic organisms.

Photo: TUM/J. Geist


The throughflow is decisive for the bottom of a body of water and the chance to change the course of the river creates habitat.

Photo: TUM/J. Geist

The tertiary hill country, 65 million years old, is among the areas with the highest erosion rates. However, less than one percent of the erosion material remains on the ground and the siltation problem cannot be solved by reducing the erosion. This result was provided by the analysis of riverbed samples over the course of several years by Professor Karl Auerswald from the Chair of Grassland Studies and Professor Jürgen Geist from the Chair of Aquatic Systems Biology.

“The prevention of erosion alone, as water and fisheries management have long demanded, does not then help river beds,” says Professor Auerswald. Fortified and dammed as well as straightened and deepened over many decades, the rivers lack their natural flow behavior. Likewise, the floodplain landscape is lacking buffer function and interplay with the river during flooding. The Moosach diagnosis: “a channel, no longer a river” can be transferred to all rivers in Bavaria and worldwide, says the TUM professor.

The Disappearance of Natural Change

The two TUM scientists just published the results of their study in the international journal “Land Degradation & Development.” The title, “Extent and causes of siltation in a headwater stream bed: catchment soil erosion is less important than internal stream processes,” shows how important the throughflow is for the riverbed. Namely the cavities between the gravel filled with oxygen-containing water gravel constitute the primary refuge of small and micro-organisms as well as the egg-laying site for various river fish. Even a thin sediment layer suffices to seal these interstices.

“The entry of erosion material also occurs under natural conditions,” Auerswald explains. “Under natural conditions, however, the riverbed is constantly being relocated and the cavity system is cleared from the inundated floodplain by the groundwater flow.” Because rivers have been straightened and channeled, these floodplain dynamics disappear just as the natural inflow from below has greatly decreased.

Humankind initially intervened in the course of the rivers with good reason: In order to protect cities from flooding, to drain swamps, and to push back cholera and typhus, at the start of the 19th century, rivers began to be straightened and forced into canals. Thus, land was also won for further settlement. The floodplain landscapes, important for sediment retention and natural flood protection, became dysfunctional more and more. Thus, the rivers lacking in shores and natural water inflow lack the possibility of change. But it is precisely these differences that are decisive for the biodiversity of a body of water and for its wealth of species in the water and below.

Auerswald warns: “River floodplains must be off-limits”

The right measure is lacking for Auerswald: “As is so often the case, humans continue down a path that was initially correct, even if he’s already well past the goal.” In the case of local planning and construction decisions, the floodplain is “always the loser.” Auerswald advises, as he has for many years, to once again give the rivers the freedom to determine their own shape.

This means, consequently, that the river could shape its bed during renaturation measures. “Whatever floodplains are still around must absolutely be off-limits,” he says, warning against the unchecked need of the cities for land to develop – and in view of his model calculations on future flood events: “We would do well to allow the rivers to meander on their own again.”

Publication:
Karl Auerswald und Jürgen Geist: Extent and Causes of Siltation in a Headwater Stream Bed: Catchment Soil Erosion is Less Important than Internal Stream Processes, Land Degradation & Development, 6 September 2017.
DOI: 10.1002/ldr.2779
Link: http://onlinelibrary.wiley.com/doi/10.1002/ldr.2779/full

Contact:
Prof. Dr. Karl Auerswald
Technical University of Munich
Chair of Grassland Studies
Phone: Tel: 0049/8161/71-3965
Mail: karl.auerswald@mytum.de

Weitere Informationen:

https://www.tum.de/en/about-tum/news/press-releases/detail/article/34198/

Dr. Ulrich Marsch | Technische Universität München

More articles from Ecology, The Environment and Conservation:

nachricht Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen

nachricht Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>