MONITORING CHANGING POSITION OF THE SHORELINE ALONG BURULLUSBALTIM, NILE DELTA, EGYPT, AND THE RULE OF COASTAL DUNES AS A NATURAL DEFENSE AGAINST EROSION IN A GEO-HERITAGE SITE: REMOTE SENSING APPLICATION

Monitoring the coastal area along the Burullus-Baltim coast shows that it is a fragile coastal area
composed of loose sand eroded from the old Sebennitic Promontory since historical time of more than
1000 years, then enhanced after the construction of Aswan High Dam (AHD).
The interplay of waves, wind and sands along this coast led to construction of a unique geomorphosite
with the characteristic barchan and linear sand dunes. Due to the high threshold velocity that reached at
Baltim (Vt) 19.38 cm sec-1, such velocity is able to blow sands with diameter D50 of 250􀝑m. The velocity
need for suspending the D50 to an elevation Z (Vz=5m) is equal to 630 cm sec-1. Contrary is the case to
the east at Gamasa where the Vt equal to 16.3 cm sec-1 and the Vz for suspending the D50 (180 􀝑m at
Gamasa) is equal to 560 cm sec-1 . This may explain why the dunes at Baltim are coarser in grain diameter
and together withthe tight back desert strip explain the presence of Baltim dunes at elevations more than
20m, while at Gamasa not exceeds 5m. These dunes represent natural defence measures for the barrier
beach separating the Burullus Lake from the Mediterranean Sea. Due to human intervention including
urban extension and agricultural activities much of these dunes were deteriorated and diminished from
174.8km2 to 6.4km2. The project of extraction and concentration of heavy minerals from sand dunes seem
uneconomic. Although the heavy mineral concentration is more than 5%, more than half of the detected
minerals is Ilmenite, which is neitherstrategic nor economic mineral. Such project may add new form of
hazards. Although the defence measures seem effective in protecting the coast, several rates of erosion and
accretion were detected along the studied sectors, and the shoreline does not retain its present position in
many areas of the coast since 1984.