The Urban Heat Island (UHI) results in significant and sometimes dramatic increases in air temperature differences between the urban environment and its surrounding areas. The heat island structure may extend from the...The Urban Heat Island (UHI) results in significant and sometimes dramatic increases in air temperature differences between the urban environment and its surrounding areas. The heat island structure may extend from the ground to the top of roofs and canopy levels above ground. The Urban Heat Island effect is a leading factor in a long list of human health problems which are expected to increase with the rapid growth of urban populations and projected future climate change. Urban heat island studies can be conducted through either direct measurements of air temperature using automobile transects and weather station networks or through measuring surface temperature using airborne or satellite remote sensing. In this study, UHI was investigated over the Greater Cairo during both summer and winter seasons over two different dates. Landsat 7 ETM+ data were used and the mono-window algorithm was applied in the study. Results emphasis that both types of heat islands exist in the study area i.e. the surface and the atmospheric heat islands. Temperature differences ranged between 0.5°C to 3.5°C and these are much related to the existing land use/covers. It could be concluded that expansion of urban areas in Greater Cairo has led to increased thermal radiation of land surface on the highly populated areas.展开更多
Sand dune movement is a hazardous phenomenon in Egypt and creates major threat on the existing land use and land cover as well as developmental plans. This paper studied the sand dune morphology and quantified the rat...Sand dune movement is a hazardous phenomenon in Egypt and creates major threat on the existing land use and land cover as well as developmental plans. This paper studied the sand dune morphology and quantified the rate of sand dune movements and direction in a newly developed project in the southwest of Egypt. Two dates of satellite imageries were used to trace the Barchan dunes at various sites with different morphological properties to estimate the annual movement rate based on point to point geo-correlations. 149 dunes of the common sand dunes in the area of study including barchans and transverse dunes were studied to accurately determine their rate of movements, which ranged from 1.3 to 19.3 my-1. The direction of sand dune movements was mainly to the south and slightly southeast with range from 265 to 295 degrees. The quantification of sand dune movement and direction has, indeed, enabled to determine the major threat on the exiting land use and land cover as well as the newly developmental projects.展开更多
文摘The Urban Heat Island (UHI) results in significant and sometimes dramatic increases in air temperature differences between the urban environment and its surrounding areas. The heat island structure may extend from the ground to the top of roofs and canopy levels above ground. The Urban Heat Island effect is a leading factor in a long list of human health problems which are expected to increase with the rapid growth of urban populations and projected future climate change. Urban heat island studies can be conducted through either direct measurements of air temperature using automobile transects and weather station networks or through measuring surface temperature using airborne or satellite remote sensing. In this study, UHI was investigated over the Greater Cairo during both summer and winter seasons over two different dates. Landsat 7 ETM+ data were used and the mono-window algorithm was applied in the study. Results emphasis that both types of heat islands exist in the study area i.e. the surface and the atmospheric heat islands. Temperature differences ranged between 0.5°C to 3.5°C and these are much related to the existing land use/covers. It could be concluded that expansion of urban areas in Greater Cairo has led to increased thermal radiation of land surface on the highly populated areas.
文摘Sand dune movement is a hazardous phenomenon in Egypt and creates major threat on the existing land use and land cover as well as developmental plans. This paper studied the sand dune morphology and quantified the rate of sand dune movements and direction in a newly developed project in the southwest of Egypt. Two dates of satellite imageries were used to trace the Barchan dunes at various sites with different morphological properties to estimate the annual movement rate based on point to point geo-correlations. 149 dunes of the common sand dunes in the area of study including barchans and transverse dunes were studied to accurately determine their rate of movements, which ranged from 1.3 to 19.3 my-1. The direction of sand dune movements was mainly to the south and slightly southeast with range from 265 to 295 degrees. The quantification of sand dune movement and direction has, indeed, enabled to determine the major threat on the exiting land use and land cover as well as the newly developmental projects.
