(Press-News.org) By adding information about the subsoil to an existing sedimentation and erosion model, researchers at Delft University of Technology (TU Delft, The Netherlands) have obtained a clearer picture of how rivers and deltas develop over time. A better understanding of the interaction between the subsoil and flow processes in a river-delta system can play a key role in civil engineering (delta management), but also in geology (especially in the work of reservoir geologists). Nathanaël Geleynse et al. recently published in the journals Geophysical Research Letters and Earth and Planetary Science Letters.
Model
Many factors are involved in how a river behaves and the creation of a river delta. Firstly, of course, there is the river itself. What kind of material does it transport to the delta? Does this material consist of small particles (clay) or larger particles (sand)? But other important factors include the extent of the tidal differences at the coast and the height of the waves whipped up by the wind. In this study, researchers at TU Delft are working together with Deltares and making use of the institute's computer models (Delft3D software). These models already take a large number of variables into account. Geleynse et al. have now supplemented them with information on the subsoil. It transpires that this variable also exerts a significant influence on how the river behaves and the closely related process of delta formation.
Room for the River
The extra dimension that Geleynse et al. have added to the model is important to delta management, among other things. If – as the Delta Commission recommends – we should be creating "Room for the River", it is important to know what a river will do with that space. Nathanaël Geleynse explains: "Existing data do not enable us to give ready-made answers to specific management questions ... nature is not so easily tamed ... but they do offer plausible explanations for the patterns and shapes we see on the surface. The flow system carries the signature of the subsoil, something we were relatively unaware of until now. Our model provides ample scope for further development and for studying various scenarios in the current structure."
Geological information
River management is all about short-term and possible future scenarios. But the model developed by Geleynse et al. also offers greater insight into how a river/delta has developed over thousands of years. What might the subsoil have looked like and – a key factor for the oil industry – where might you expect to find oil reserves and what might their geometrical characteristics be? In combination with data from a limited number of core samples and other local measurements, the model can give a more detailed picture of the area in question than was possible until now.
The link between the creation of the delta and the structure of the delta subsoil is also of interest to engineers who wish to build there. Hundreds of millions of people across the globe live in deltas and these urban deltas are only expected to grow in the decades to come.
INFORMATION:
Further details
'Controls on river delta formation; insights from numerical modelling', Nathanaël Geleynse, Joep Storms, Dirk-Jan Walstra, Albert Jagers, Zheng Wang and Marcel Stive. Earth Planet. Sci. Lett., Volume 302, Issues 1-2, 1 February 2011, Pages 217-226, http://dx.doi.org/10.1016/j.epsl.2010.12.013
'Modeling of a mixed-load fluvio-deltaic system', N. Geleynse, J.E.A. Storms, M.J.F. Stive, H.R.A. Jagers, and D.J.R. Walstra, Geophys. Res. Lett., 37, L05402, http://dx.doi.org/10.1029/2009GL042000
Contact: Nathanaël Geleynse, Faculty of Civil Engineering and Geosciences, N.Geleynse@tudelft.nl, +31 (0)15 2784419
TU Delft Science Information Officer Roy Meijer, r.e.t.meijer@tudelft.nl, +31 (0)15 2781751
A clearer picture of how rivers and deltas develop
2011-01-26
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
Insects that deter predators produce fewer offspring
2011-01-26
Scientists studied the defences used by caterpillars that transform into large white butterflies, called Pieris brassicae. The insects regurgitate semi-digested cabbage leaves to make them smell and taste unpleasant to predators. The team found, however, that frequent use of this defence reduces the caterpillars' growth rate and the number of eggs they produce. It remains unclear why their defences affect them in this way, but the loss of nutrition from frequent regurgitation is thought to play a part.
Caterpillars are a target of pest control, as they destroy food ...
Increased marginalization of students
2011-01-26
The successful Swedish model of reducing the impact of students' different social, cultural and economic backgrounds on academic outcome is severely threatened after 20 years of educational reforms. This is the main point made by Docent (Reader) Girma Berhanu from the University of Gothenburg in International Journal of Special Education.
Some of the previously very positive trends in the Swedish school system seem to have been put in reverse over the past 20 years, and students with special needs, immigrant students and socially disadvantaged students are getting the ...
A psychopath lacks empathy just like a person with frontal head injury
2011-01-26
"Seeing as psychopathic behavior is similar to that of a person with brain damage, it could be that it could benefit from similar forms of treatment," said Dr. Simone Shamay-Tsoory, who conducted the study.
People diagnosed as psychopathic have difficulty showing empathy, just like patients who have suffered frontal head injury. This has been shown in a new study from the University of Haifa. "Our findings show that people who have psychopathic symptoms behave as though they are suffering frontal brain damage," said Dr. Simone Shamay-Tsoory, who conducted the study.
Psychopathy ...
CSI: Manchester -- University team gets forensic on dinosaurs
2011-01-26
A new TV series featuring dinosaur detectives from The University of Manchester looking at how dinosaurs once lived, looked and functioned begins in the UK this week.
Presented by University of Manchester palaeontologist Dr Phil Manning, the series will be aired on the National Geographic Channel, starting in the UK on Thursday February 3rd, before being transmitted to many countries around the world.
It is the first ever series on dinosaurs commissioned by National Geographic, as previously documentaries have only aired as one or two-hour specials.
Jurassic CSI ...
Asian tiger numbers could triple if large-scale landscapes are protected
2011-01-26
The tiger reserves of Asia could support more than 10,000 wild tigers – three times the current number – if they are managed as large-scale landscapes that allow for connectivity between core breeding sites, a new study from some of the world's leading conservation scientists finds. The study, published in Conservation Letters, is the first assessment of the political commitment made by all 13 tiger range countries last November to double the tiger population across Asia by 2022.
"A Landscape-Based Conservation Strategy to Double the Wild Tiger Population" finds that ...
Patients infected with HIV have higher drop-out rate for liver transplantation
2011-01-26
French researchers determined that infection with human immunodeficiency virus (HIV) impaired results of transplant surgery for liver cancer, with more HIV infected patients dropping off the transplantation wait list. The team found that overall survival and recurrence-free survival was not impacted following liver transplantation in patients with controlled HIV disease. Details of this single center study—the largest to date—are published in the February issue of Hepatology, a peer-reviewed journal of the American Association for the Study of Liver Diseases (AASLD).
More ...
Researchers identify gene variants linked to hepatitis C treatment-related anemia
2011-01-26
In two recent studies, researchers have identified two functional variants in the inosine triphosphatase (ITPA) gene that protect patients with hepatitis C virus (HCV) against anemia brought on by antiviral treatment. The ability to identify those patients protected against treatment-induced anemia will ensure completion of antiviral therapy and successful elimination of the virus. Full findings of these studies appear in the February issue of Hepatology, a journal published by Wiley-Blackwell on behalf of the American Association for the Study of Liver Diseases.
Chronic ...
Climate tax on meat and milk results in less greenhouse gases
2011-01-26
A climate tax corresponding to €60/ton CO2eq on meat and milk could reduce
greenhouse gas emissions from European agriculture by around seven per cent. If the land made available is used for bioenergy production, the decrease in emissions can be six times greater. This is shown by the researchers Kristina Mohlin, Stefan Wirsenius and Fredrik Hedenus, University of Gothenburg, Sweden, in an article published in the scientific journal Climatic Change.
Kristina Mohlin is a PhD student at the Department of Economics at the University of Gothenburg. She wrote the article ...
The embryogenesis evidence of foregut duplication cyst
2011-01-26
Foregut duplication cyst of the stomach is rare. Foregut duplications may or may not communicate with the gastrointestinal tract, and are usually diagnosed at a young age. There have been relatively few case reports describing this entity. Adenocarcinoma has been reported in four cases of gastric duplication cyst, but not in cysts that have a ciliated epithelium. Controversy exists concerning the embryological origin of these anomalies.
A research article to be published on January 7, 2011 in the World Journal of Gastroenterology addresses this question. The authors presented ...
Useful biomarkers for esophageal squamous cell carcinoma
2011-01-26
MicroRNAs (miRNAs) regulate gene expression by mainly binding to the 3′-UTR of target mRNAs, leading to mRNA degradation or translation inhibition. Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies in China. Many studies have reported the miRNA expression profiles in Barrett's esophagus and esophageal adenocarcinoma. However, the pathobiological significance of aberrant miRNA expression in human ESCC has not been well documented.
A research article to be published on January 7, 2011 in the World Journal of Gastroenterology addresses ...