A study on sand dune forms southeast of Jeddah, Saudi Arabia

الملخص EN

-The drifting sand and dune movement pose serious geohazard on urban development and road construction in the Kingdom of Saudi Arabia.

This fact initiated several research projects in a number of universities and research institutes in the Kingdom.

Two locations of inter mountain dune fields east and southeast of Jeddah were investigated and the dune forms were identified.

In addition to the sand sheets, the major dune type is the reversal linear dunes coexisting with few small barchan dunes.

Detailed investigations on the linear dunes indicated that the ultimate direction of movement of the dunes is downwind along their crest line.

However, during their migration, the dunes wander laterally in both directions but more in one direction than the other depending on the frequency of the prevailing wind and configuration of the surrounding mountains.

The sand from the two locations was found to be similar in their grain size parameters.

Some variations, however, were observed both along the crest line and across the dune body.

Mineralogically, the sand reflects the composition of the surrounding igneous, metamorphic and sedimentary rocks.

The results of cone penetration tests were used to reconstruct a possible cross section for the linear dune which is slightly different from the existing hypothetical sections.

A reasonable similarity was obtained between the studied dunes and the linear dunes existing in Al Nufud but some differences were found between the sand from these dunes and the other dune forms in Al Jafurah and Ad Dahna sand seas.

The sections of the highways crossing these dune fields are either parallel or intersect the dune crest lines at small angle.

The dunes, therefore, pose only minor sand drifting hazard on these highways.

A forest is suggested to be established to control this hazard and minimize the waste water ponding problems.