Profile measurement and simulation of a transverse dune field in the Len\c{c}\'ois Maranhenses

TL;DR

This study combines field measurements and simulations to analyze the height profiles, spacing, and morphology of transverse dunes in Lençóis Maranhenses, revealing new relationships and validating a dune model.

Contribution

It introduces a relation for dune spacing based on field data and validates a two-dimensional dune model against real transverse dune fields.

Findings

Dunes with similar heights show variable brink positions.

The model reproduces inter-dune distances and aspect ratios.

A new relation for dune spacing as a function of brink-crest distance.

Abstract

In this work, we report measurements of the height profile of transverse dunes in the coastal dune field known as ``Len\c{c}\'ois Maranhenses'', northeastern Brazil. Our measurements show that transverse dunes with approximately the same height present a variable brink position relative to the crest, in contrast to the case of barchan dunes. Based on our field data, we present a relation for the dune spacing as a function of the crest-brink distances of transverse dunes. Furthermore, we compare the measurements with simulations of transverse dunes obtained from a two-dimensional dune model, where a phenomenological definition is introduced for the length of the separation streamlines on the lee side of closely spaced transverse dunes. We find that our model reproduces transverse dune fields with similar inter-dune distances and dune aspect ratios as measured in the field.