RATES OF AEOLIAN TRANSPORT ON A BEACH IN A TEMPERATE HUMID CLIMATE

Short term field measurements of aeolian transport, using a saltiphone , indicate that actual rates of transport deviate considerably from th e potential rates predicted by transport equations. When examined in d etail, however, potential rates are approached during special conditio ns: mostly when the wind blows offshore, parallel or slightly oblique to the beach and relative humidity is below 85%. Also, the potential r ates of transport may be approached when wind speeds considerably exce ed threshold speed, even during showers. The main cause of the large d eviation of actual from potential rates is in the absence of transport during very wet conditions (prolonged rainfall) regardless of wind sp eed, and the variation of threshold velocity with time. The threshold velocity increases during wet conditions, with onshore winds or becaus e of the presence of algae. Therefore, potential transport is defined as the transport optimum. To predict the actual rates of transport acc urately, insight into the variation of the threshold velocity is essen tial. Aeolian transport of sand seems to be related to moderate events and not to extreme events, conforming to the principle of magnitude a nd frequency.