Abstract

MALTA, Júlia Varella  and  AMARAL, Ricardo Farias do. Sediment Flow Experiment in a segment of Jenipabú Coastal Dunes, East Coast of Rio Grande do Norte, Brazil. RGCI [online]. 2013, vol.13, n.1, pp.61-78. ISSN 1646-8872.  https://doi.org/10.5894/rgci348.

These study made the analysis of the measurement of the aeolian transport using vertical sand traps across the dune field of Jenipabu, in the municipality of Extremoz, Rio Grande do Norte state, northern of the city of Natal. These measurements were used as a parameter of the sand aeolian transport in the region. There were made three field trips in September 2011 in September 13^th (campo “a”), 21st (campo “b”) and 29th (campo “c”), time of the year where the wind speed is the higher, and one in December 08th of 2011(campo “d”), time of the year where the wind speed starts to decrease. Through four longitudinal profiles of the Jenipabu’s dune fields were used 3 types of cylindrical aeolian traps made of CPV: type “I” with the collecting opening of 25 cm from the surface level, and “S” with the collecting opening of 25 cm from 25 cm of the surface level in six collect points in one of the September 13th (campo “a”) field trips and another in December 08th (campo “d”), and sand traps type “T” with the collecting opening of 50 cm from the surface level, in the other field trips in September 21st e 29th (campo “b” e “c”) across the dune field of Jenipabu. The meteorological data were gotten in situ with a portable meteorological station and those data were complimented with those from the Natal Meteorological Station away about 12 km from the study area. The sediments that were collected with the sand traps were washed and weighed, with it was calculated sediment wind load. In September the sediment flux varied from 0,01 to 11,39Kg. m^-1. h^-1 and in December from 0,01 to 11,39 Kg. m^-1. h^-1 with the type “T” sand traps. While in the type “I” sand traps the wind load varied from 0,33 to 1,30 Kg. m^-1. h^-1, and with the type “S” sand traps the wind load varied from 0,01 to 0.73 Kg. m^-1. h^-1. According the statistic analyses the sediment transport increases in direct proportion to the wind speed, except in the samples collected with the type “S” sand traps where there were found a F= 0,139808. The aeolian transport is more intense in the first 25cm from de surface (Q=8 Kg. m^-1. h^-1), whereas in over 25cm from the surface the wind load values were less than 0,35 Kg. m^-1. h^-1. Nowadays the human occupation shuts the sediment supply from the Santa Rita beach into the dune field of Jenipabu, which in addition to the rise of the wind speed profile makes the aeolian transport more intense from the middle to the top of the dune. Where there are sparsely vegetated the displacement free dune face increases the clogging process of the Jenipabu pond, a important regional tourist destination.

Keywords : Mobile dunes; sand traps; wind speed; morphodynamics; coastal management.

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