Dust Measurements in the Egyptian Northwest Coastal Zone

Abstract

Standard dust sampling equipment was used to collect eroded aerosol samples from 52 wind erosion events in the Northwest Coastal Zone (NWCZ) of Egypt. The eroded samples were analyzed to determine the transport mass for each erosion event over a 3-year period from farm fields at Fuka and Abu Lahu. Weather, soil roughness, rock cover, and vegetative cover data were collected to provide input to the Revised Wind Erosion Equation (RWEQ) model to estimate transport mass. Annual rainfall in the NWCZ is much lower, soils have more surface stones, and crop planting and harvesting methods are much different from test sites in the U.S., where similar wind erosion studies on transport mass have been conducted. The soil at Fuka is 2.3 times more erodible by wind than the soil at Abu Lahu. Stone cover varied from 0% to 30% and 0% to 27%, and vegetative cover varied from 0% to 18% and 2% to 50% at Abu Lahu and Fuka, respectively. Soil ridge height was 0 to 10 cm and ridge spacing was 40 cm at both sites. Because of the large stones at Fuka and numerous round stones at Abu Lahu, a stone silhouette coefficient (Ssc) was developed in the Desert Research Institute at Cairo and used to estimate transport mass with RWEQ. Fifty-six percent and 62% of the erosion events in the NWCZ occurred in February, March, or April, and 59% and 83% of the events lasted between 11 to 20 h at Fuka and Abu Lahu, respectively. Maximum measured transport mass was 261.7 kg/m-width at Abu Lahu and 737.5 kg/m-width at Fuka. Maximum estimated transport mass with RWEQ was 285.9 kg/m-width at Abu Lahu and 649.8 kg/m-width at Fuka. The coefficient of determination was r2 = 0.93 for 60 clusters of measured and estimated transport mass at Fuka. For 44 clusters of measured and estimated transport mass at Abu Lahu, the coefficient of determination was r2 = 0.91. The RWEQ model with the stone silhouette coefficient can be used to describe wind erosion in the semi-arid Northwest Coastal Zone of Egypt. The RWEQ model can also be used to evaluate new management systems that utilize available resources to minimize wind erosion.