Textural Characteristics of Coastal Sediments Wadi Al- Fagh and Wadi Al-Qunfidah, Southeastern Red Sea PDF

Keywords

sediments, wadi, sands

Abstract

Grain-size variation of sediments in different environments of the coastal zone between Wadi Al-Fagh and Wadi Al-Qunfidah, eastern Red Sea were studied. The wadi sediments are generally muddy gravely sand exhibiting a general downstream decrease in the mean grain-size. The bed material of wadis in the northern part of the study area is markedly finer than that of wadis in the southern part, where gravel-sized sediments are more common. The sediments distribution reflects short-lived flood flow patterns in the wadis. The remarkable changes in the texture characteristics of sediments of the northern wadis are considered to be due to the rainfall increase to the south. The dune sands of eolian origin are well to moderately sorted with a narrow range in the mean size (1.92- 2.85Ф). Generally, the beach sediments are medium to fine sands, well to moderately sorted and to a great extent negatively skewed. The intertidal and subtidal sediments both exhibit a wide range of textural characteristics. The intertidal sediments are generally coarser than those of subtidal zone. Also in the south of the studied region, sediments from the tidal zones in the deltas fronting wadis Al Dugh, and Ahsibah, are markedly coarser than elsewhere in the region. In the north of the area the relationships appear to be different particularly with respect to the intertidal sediments where the sediments from between the wadis is coarser than that in front of the wadis. The terrigenous sediments from the wadis are mixed with locally produced carbonate in varying proportions in the beach and littoral zones. Such mixing and subsequent reworking by the nearshore processes result in the observed variation in texture. There does not, however, appear to be any correlation between mean size and the relative proportions of the carbonate to terrigenous material in the sediments