Monitoring shoreline changes and aeolian sand encroachment, Nasser Lake, Egypt, using remote sensing and GIS techniques

Sand encroachment takes place when sand grains are transported by winds and collect on the glide, along watercourses. The drifts of dunes are the most important events leading to future disasters. Monitoring shoreline changes and mapping these changes at Nasser Lake using GIS and remote sensing techniques at regular periods represents the first significant step in accurately characterizing the problem. The data show a relationship between shoreline morphology, dune morphology and erosion/accretion. The analysis results show that the sands encroaching on the lake are in the shape of sand sheets, not dunes. Change detection was observed on images, and at the same time it was not possible to find rates of sand drift through remote sensing only. Nevertheless, it was found that the origin of sand is further north and that the wind, which is oriented south to southeastward, deposits its load near the lake or in it. Mitigation of dynamic sand should involve consideration of its source, corridors of movement and the site or sites of deposition. Zoning of the fluvial zone for regulatory design and assessing the potential impact of rising water levels indicates severe erosion in many locations, due to reduction in sediment supply by recharge dams and roads and the long-term process of rising water levels.