نتایج جستجو برای: dune
تعداد نتایج: 2774 فیلتر نتایج به سال:
In coastal regions, water, wind, gravitation, vegetation, and human activity continuously alter landscape surfaces. Visualizations are important for understanding coastal landscape evolution and its driving processes. Visualizing change in highly dynamic coastal terrain poses a formidable challenge; the combination of natural and anthropogenic forces leads to cycles of retreat and recovery and ...
Introduction Yueya Spring, or Crescent Moon Spring, is a geological wonder located about 6 km south of Dunhuang city, Gansu Province, northwest China. It owes its name to the shape of the spring, or more precisely, the pond fed by the spring water, which resembles a Crescent Moon (Figure 1). Currently, the pond is about 200 m long in an east-west direction and about 50 m wide. The water surface...
The present recommendations for dune removal or dune retreat on the Great Lakes for Federal Emergency Management Agency (FEMA) flood mapping purposes are based on a simple geometric method as outlined in FEMA (2009). The simple procedure establishes a relationship between dune survival and storm intensity. The method was adopted several decades ago when numerical models were inadequate for pred...
In this study, the soil moisture content was measured, and the quantitative characteristics of this sedge species were compared. The phenotypic plasticity of each parameter and the linear regression relationships were analyzed. The results showed that the soil moisture content was significantly affected by location, soil depth, and sampling date. The aboveground biomass, underground biomass, bi...
Barchans are crescentic dunes propagating on a solid ground. They form dune fields in the shape of elongated corridors in which the size and spacing between dunes are rather well selected. We show that even very realistic models for solitary dunes do not reproduce these corridors. Instead, two instabilities take place. First, barchans receive a sand flux at their back proportional to their widt...
We study in detail the photometric redshift requirements needed for tomographic weak gravitational lensing in order to measure accurately the Dark Energy equation of state. In particular, we examine how ground-based photometry (u,g,r,i,z,y) can be complemented by space-based near-infrared (IR) photometry (J,H), e.g. on board the planned DUNE satellite. Using realistic photometric redshift simul...
Many species are adapted to disturbance and occur within dynamic, mosaic landscapes that contain early and late successional microhabitats. Human modification of disturbance regimes alters the availability of microhabitats and may affect the viability of species in these ecosystems. Because restoring historical disturbance regimes is typically expensive and requires action at large spatial scal...
[1] Desert booming can be heard after a natural slumping event or during a sand avalanche generated by humans sliding down the slip face of a large dune. The sound is remarkable because it is composed of one dominant audible frequency (70 to 105 Hz) plus several higher harmonics. This study challenges earlier reports that the dunes’ frequency is a function of average grain size by demonstrating...
The general flow structure over transverse aeolian dunes is now well documented through both field studies and wind tunnel experiments. Research on windward (stoss) slopes of dunes is extensive and has recently been complemented by research on the lee-side flow structure. However, a number of technical deficiencies in wind tunnel instrumentation and a lack of detailed resolution in and appropri...
INTERISLAND VARIABILITY OF DUNE PLANT COMMUNITY STRUCTURE ON VIRGINIA’S BARRIER ISLANDS Justin K. Shafer Old Dominion University, 2010 Director: Dr. Frank P. Day The barrier islands of the Virginia Coast Reserve LTER site provide an opportunity to study interisland variability of dune plant communities. My research focused on the variation in biomass and diversity of communities among islands a...
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