A method for establishing the critical threshold for aeolian transport in the field
Aeolian features ; Aeolian transport ; Arid area ; Dune ; Methodology ; Texas ; Threshold ; United States of America ; Wind erosion ; Wind speed
A mathematical expression that relates saltation activity and relative wind strength was reformulated so that threshold may be calculated from measurements of saltation activity and the mean and standard deviation of wind speed. To test the new
. It was found that during periods of active aeolian activity, threshold values could be calculated every 5 minutes.
Drainage basin sensitivity to tectonic and climatic forcing : implications of a stochastic model for the role of entrainment and erosion thresholds
Earth surface processes ; Erosion ; Erosion rate ; Model ; Precipitation ; Runoff ; Sediment transport ; Stochastic model ; Threshold ; Watershed
The A. describes a stochastic model for modelling long-term sediment transport and erosion rates that (a) incorporates an erosion threshold, and (b) captures the integrated effects of a spectrum of runoff events. Solutions are derived
and numerically tested for 3 erosion/transport formulas : The Howard-Kerby shear-stress incision model, the Bridge-Domininic sediment transport model, and a generic shear-stress sediment transport model. Results imply that non-linearity resulting from threshold
China ; City size ; Methodology ; Population size ; Rank-size distribution ; Sampling ; Threshold ; Town ; Urban population ; Urban system
This study tests three existing threshold methods (number threshold, size threshold, and urban pop-ulation percentage threshold) using China’s city system as a case study. In addition, it proposes a new method based upon the percentage threshold
of the total number of cities. The results show that Pareto exponent is sensitive to sample size and the truncation point. Furthermore, this method yields a consistent set of results over a wide range of thresholds. Finally, when using this new method
diagram and a lower boundary was clearly noticeable : it was interpreted as a threshold representing the rainfall conditions associated to landsliding which is consistent with literature thresholds. The influence of predisposing factors (such as lithology
and land use) and rainfall characteristics was investigated as well and statistical analysis revealed to be the most effective way to define a more advanced early warning system based on a set of multiple thresholds. Four thresholds corresponding to four
Threshold conditions for thalweg gullying with special reference to loess areas
Climatic and hydraulic threshold conditions for thalweg incision are discussed on the basis of a physical-mathematical model, which includes such parameters as the critical shear stress of flows for non-selective erosion in loess, flow width
Thresholds for channel change on two contrasting pro-glacial river fans, West Greenland
Thresholds for channel change were investigated on two proglacial outwash fans, one silty, the other gravelly, over different temporal and spatial scales. Model outputs were defined in terms of planimetric change, braiding intensity, fan incision
Rethinking the analysis of ethnic residential patterns : segregation, isolation, or concentration thresholds in Auckland, New Zealand ?
Data from the 1996 New Zealand Census on ethnicity in Auckland are used to illustrate a new approach to measuring spatial separation. The method is based on thresholds. This provides more detailed information on the geography of ethnic groups
Threshold relations for the transport of sediment by overland flow on desert hillslopes
on runoff plots in southern Arizona. Because the data deviate in a systematic manner from the Shields relation, alternative threshold relations are developed and discussed.
Threshold response of small streams to surface coal minig, bitumous coal fields, central Pennsylvania
by means of scatter plots, correlation, cluster analysis and bivariate regression. For streams that have exceeded threshold levels, disequilibrium is demonstrated by a strong, positive correlation between local stream slope and basin area.
The effects of surface moisture on aeolian sediment transport threshold and mass flux on a beach
Aeolian features ; Aeolian transport ; Beach ; Canada ; Coastal environment ; Coastal erosion ; Dune ; Nova Scotia ; Prince Edward Island ; Sand ; Soil moisture ; Threshold
This paper presents results from a study designed to explore the effects of beach surface moisture and fetch effects on the threshold of movement, intensity of sand transport by wind and mass flux. The experiment was carried out over a period of 5
Wind-tunnel modelling of the influence of vegetation structure on saltation threshold
were conducted to determine the quantitative influence of vegetation structural attributes on saltation threshold. To this end, the influence on saltation threshold of lateral cover (also known as roughness density), element aspect ratio AR (= height
A large and geographically diverse data set consisting of meandering, braiding, incising, and post-incision equilibrium streams was used in conjunction with logistic regression analysis to develop a probabilistic approach to predicting thresholds
Alps (The) ; Applied geomorphology ; Groundwater ; Italy ; Landslide ; Mass movement ; Model ; Mountain ; Natural hazards ; Slope dynamics ; Threshold
In this paper the mobility of the landslide of Alverà is analysed over a period of three years based on daily observations of groundwater level and velocity measurements. The aim was to identify critical thresholds in the mobility of this landslide
: a lower threshold for the onset of movement and an upper threshold for catastrophic failure. A second aim was to assess the temporal variation of the viscosity index and to find out whether there is a trend to strain softening of the material (lowering
Rainfall thresholds for shallow landsliding derived from pressure-head monitoring : cases with permeable and impermeable bedrocks in Boso Peninsula, Japan
Rainfall thresholds for shallow landslide initiation were determined for hillslopes with 2 types of bedrock, permeable sandstone and impermeable mudstone, in the Boso Peninsula. Detailed field and laboratory investigations were designed to ascertain
Experimentation ; Research technique ; Runoff ; Threshold ; Turbulence
This technical communication presents some MATLAB routines for visualizing the structure in turbulent signals based on a standard conditional averaging and thresholding approach. The latter information is derived from a wavelet decomposition