scholarly journals PREDICTION OF WIND-DRIVEN TRANSPORT RATE

1986 ◽  
Vol 1 (20) ◽  
pp. 117
Author(s):  
D.H. Swart
Keyword(s):  
Sand Dune ◽  
Management Strategies ◽  
Transport Rate ◽  
Sand Transport ◽  
Aeolian Transport ◽  
Dune Field ◽  
Best Estimate ◽  
Effective Manner ◽  
Sand Movement ◽  
The Subject

The rate of wind-driven sand movement in a dune field is an important parameter needed to establish management strategies for sand dune fields. Until recently not much attention has been given in engineering circles to the possible effect of wind-blown sand transport. However, there is a wealth of literature on the subject which goes back as far as 1936. A study of literature reveals that there are at least 16 formulae for the prediction of the aeolian transport rates which are readily available. This paper describes a technique which utilizes these 16 formulae in the most effective manner for predicting the best estimate of the potential wind-blown transport rate. Restrictions on the applicability of the method are discussed and fields for further research are recommended.

scholarly journals The Sources of Moisture in the Sand Dunes – The Example of the Western Sahara Dune Field

2014 ◽  
Vol 33 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Elwira Żmudzka ◽  
Dariusz Woronko ◽  
Maciej Dłużewski
Keyword(s):  
Surface Layer ◽  
Moisture Content ◽  
Wind Velocity ◽  
Sand Dune ◽  
Sand Dunes ◽  
Shear Velocity ◽  
Meteorological Conditions ◽  
Aeolian Transport ◽  
Western Sahara ◽  
Dune Field

Abstract Climatic and meteorological conditions may limit the aeolian transport within barchans. An explanation of that issue was the main goal of the investigation held in Western Sahara dune fields located around Tarfaya and Laâyoune. Particular attention was paid to the factors causing the moisture content rising of the sand dune surface layer, which could influence the wind threshold shear velocity in the aeolian transport. The wetted surface layer of sand, when receiving moisture from precipitation or suspensions, reduces the aeolian transport, even in case of wind velocity above 4-5 m s-1. Fog and dew condensation does not affect the moisture of deeper sand layers, what occurs after rainfall.

scholarly journals LABORATORY STUDY ON SAND TRANSPORT OVER RIPPLES DUE TO ASYMMETRIC OSCILLATORY FLOWS

1986 ◽  
Vol 1 (20) ◽  
pp. 109 ◽  
Author(s):  
Shinji Sato ◽  
Kiyoshi Horikawa
Keyword(s):  
Laboratory Study ◽  
Oscillatory Flow ◽  
Transport Rate ◽  
Sand Transport ◽  
Hydraulic Parameters ◽  
Oscillatory Flows ◽  
Sand Transport Rate ◽  
Bed Forms ◽  
Sand Movement

Mechanism of sand movement due to asymmetric oscillatory flows was investigated through experiments. Measurements of bed forms, suspended sand concentration and net sand transport rate were carried out by using an oscillatory flow tunnel. The process of entrainment and suspension of sand above asymmetric ripples was quantitatively described. The geometry of ripples and the net sand transport rate in regular and irregular flows were expressed in terms of hydraulic parameters characterizing the oscillatory flow. Two-dimensionality of ripples was found to be an important factor in the estimation of the net sand transport rate.

scholarly journals CALCULATION OF ON-OFFSHORE SAND MOVEMENT AND WAVE DEFORMATION ON TWO-DIMENSIONAL WAVE-CURRENT COEXISTENT SYSTEM

1988 ◽  
Vol 1 (21) ◽  
pp. 90
Author(s):  
Koichi Kinose ◽  
Shuji Okushima ◽  
Masahito Tsuru
Keyword(s):  
Wave Height ◽  
Experimental Results ◽  
Breaking Point ◽  
Transport Rate ◽  
Sand Transport ◽  
Height Distribution ◽  
Wave Deformation ◽  
Sand Transport Rate ◽  
Sand Drift ◽  
Sand Movement

In this paper, we proposed a method of calculation to predict quantitatively the on-offshore sand movement and the wave deformation on a wave-current coexistent system by assuming a river mouth. And the calculated results were compared with the experimental data obtained for the coexistent system in a twodimensional wave tank. The distribution of wave height on the breaker zone was analyzed by use of BORE MODEL. It was required for the calculation of the sand transport rate. The model was established on the assumption that the value of energy loss in a breaking wave was equivalent to that of bore. The wave height distribution on the offshore side of breaking point was presumed employing the third order approximate solution of Stokian wave on the coexistent system. The breaking point was obtained by use of Miche's criteria equation. The local sand transport rate could be calculated by use of POWER MODEL. The predominant direction of sand drift was recognized using relations for judgement which were derived from the experimental results. The transformation of sea bottom and river one was estimated on the basis of the calculated distributions of the wave height and the sand transport rate. The results obtained by this analytical method agreed well with the experimental results.

scholarly journals Using Video Monitoring to Test a Fetch-Based Aeolian Sand Transport Model

2020 ◽  
Vol 8 (2) ◽  
pp. 110 ◽  
Author(s):  
Pam Hage ◽  
Gerben Ruessink ◽  
Zilla van Aartrijk ◽  
Jasper Donker
Keyword(s):  
Wind Velocity ◽  
Transport Model ◽  
Transport Rate ◽  
Beach Sand ◽  
Sand Transport ◽  
Winter Period ◽  
Aeolian Sand ◽  
Aeolian Transport ◽  
Aeolian Sand Transport ◽  
Strong Winds

Transport of beach sand to the foredune by wind is essential for dunes to grow. The aeolian sand transport rate is related to wind velocity, but wind-based models often overpredict this transport for narrow beaches (<100 m). To better predict aeolian sand transport, the fetch-based Aeolus model was developed. Here, we qualitatively test this model by comparing its transport-rate output to visual signs of aeolian transport on video imagery collected at Egmond aan Zee, the Netherlands, during a six-month winter period. The Aeolus model and the Argus images often agree on the timing of aeolian transport days, except when transport is small; that is not always visible on the Argus images. Consistent with the imagery (minimal signs of aeolian activity in strong winds), the Aeolus model sometimes predicts the actual transport to be smaller than the potential transport. This difference is largest when wind velocity is large, and its direction is cross-shore. Although transport limitations are not predicted to be common, the results suggest that their effect on the total transport in the study period was substantial. This indicates that the fetch distance should be taken into account when calculating aeolian transport for narrow beaches on longer timescales (>weeks).

scholarly journals TOWARD AN IMPROVED EMPIRICAL FORMULA FOR LONGSHORE SAND TRANSPORT

1988 ◽  
Vol 1 (21) ◽  
pp. 88 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Kathryn J. Gingerich ◽  
Julie Dean Rosati
Keyword(s):  
Oscillatory Flow ◽  
Field Experiments ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Longshore Current ◽  
Wave Energy Dissipation ◽  
Total Transport ◽  
Local Wave ◽  
Correction Terms

This paper presents results of two field experiments performed using portable traps to obtain point measurements of the longshore sand transport rate in the surf zone. The magnitude of the transport rate per unit width of surf zone is found to depend on the product of the local wave height and mean longshore current speed, but correlation is much improved by including two correction terms, one accounting for local wave energy dissipation and the other for the fluctuation in the longshore current. The field transport rates are also found to be compatible with laboratory rates obtained under combined unidirectional and oscillatory flow. Total transport rates previously reported for this experiment program are revised with recently determined sand trapping efficiencies.

scholarly journals Spatial variation of plant species richness in a sand dune field of northeastern Inner Mongolia, China

2016 ◽  
Vol 8 (3) ◽  
pp. 434-442
Author(s):  
Jing Wu ◽  
Jianqiang Qian ◽  
Xianzhang Hou ◽  
Carlos A. Busso ◽  
Zhimin Liu ◽  
...  
Keyword(s):  
Species Richness ◽  
Spatial Variation ◽  
Plant Species ◽  
Inner Mongolia ◽  
Sand Dune ◽  
Plant Species Richness ◽  
Dune Field

scholarly journals Unwanted Overtures by Night, Remorse by Day

2019 ◽  
pp. 514-525
Author(s):  
Muna Irfan ◽  
Michel J. Howell
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sexual Behavior ◽  
Sleep Apnea ◽  
Sleep Disorders ◽  
Eye Movement ◽  
Management Strategies ◽  
Current Understanding ◽  
Obstructive Sleep ◽  
Epilepsy Treatment ◽  
The Subject

Sexual behavior in sleep has only recently been recognized as a variant of non–rapid-eye-movement (NREM) arousal parasomnias. This chapter discusses a case of sexsomnia precipitated by obstructive sleep apnea, the ensuing impact on the subject and his bed partner, and evaluation and management strategies. Sexsomnia is suspected to be highly underreported and carries significant physical, psychosocial, and forensic ramifications. Polysomnography with expanded electroencephalography can help identify concurrent sleep disorders and exclude other etiologies such as epilepsy. Treatment of comorbid sleep disorders such as obstructive sleep apnea and sleep deprivation is highly effective in controlling the abnormal sexual behavior. There is a pressing need for research and expansion of current understanding to develop a standardized approach to evaluation and management of sexsomnia.

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