Recent geomorphic changes of The Rosetta mouth (original) (raw)
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Geomorphological changes of The Rosetta mouth, Nile Delta coast, Egypt during 20th century
Most of the world's deltas mouths have become unstable during last century. This is because of the modern climatic changes as well as tectonic subsidence, but in case of The Nile Delta coast there is another effective reason; that is construction of the Aswan Low and High Dams. The construction of these Dams started at the beginning of the last century, and ended in 1970. These Dams have changed the hydraulic regime of the river downstream. One of the major environmental problems of the River Nile was the potential drop in the river channel downstream of the Dam become silt-free water, and coastal erosion in the Nile Delta coast especially in the Rosetta mouth.
Towards a Sustainable Stability of Coastal Zone at Rosetta Promontory/ Mouth, Egypt
Rosetta promontory/mouth where Rosetta branch of the Nile River meets the Mediterranean sea suffers from several severe environmental problems which began to take place since the beginning of the 20th century along Rosetta area, and increased dramatically since the construction of the Aswan High Dam (AHD) in 1964. It suffers from coastline erosion and sedimentation inside the inlet. The shoaling of the inlet leads to hindering the navigation process of fishing boats, negative impacts to estuarine and salt marsh habitat and decreases the efficiency of the cross section to transferring the flood flow to the sea. Many attempts to solve the erosion, and sedimentation problem were performed. Although, hard protection (and dredging) works have been implemented since 1989 including seawalls on the tip of the promontory and several groins along the eastern and western shores of the promontory, the problems still existing. This paper presents the results of testing a huge number of proposed alternative solutions to sustain the stable conditions of the Rosetta promontory/mouth. Hard structures, soft measures, combination of hard structures and soft measures were tested with and without nourishments of predetermined. The utilized Coastal Modeling System in testing the suggested measures was calibrated using collected field data from Ministry of Water Resources and Irrigation authorities and research institutes. The results indicated using only hard structures or soft measures without nourishment is not capable of keeping the Rosetta promontory/outlet stable. Only combination of both hard structures and soft measures with application of nourishment can improve the situation towards sustainable stable conditions but absolutely not the original stable conditions that were there before the construction of AHD.
Three Decades Monitoring of Shoreline Change Pattern of Damietta Promontory, Nile Delta, Egypt
Aquatic Science and Technology
The Nile Delta is located on the Egyptian Mediterranean coast extending along nearly 240 km from the east of Alexandria to Port Said. The coastal area of the Nile Delta Promontories has been suffering extensive erosion problem. This was achieved after the construction of many water regulation structures in Nile River as dams and barrages, particularly the Aswan High Dam. It has nearly stopped the sediment flux carried by the Nile River to the Delta. This process has caused the Mediterranean Sea to reshape the Nile Delta coastal area. In order to cease these problems several engineering hard structures have been built. These structures avoided in ceasing the problem in the site of construction but shifted the erosion problem to the adjacent sites. This study aimed to analyze the shoreline change pattern on the term of three decades during the period between 1985 to 2015 at the coastal strip of Damietta Promontory and the impact of these protective structures on the coastal area. This...
Journal of Coastal Research, 2012
El-Asmar, H.M.; El-Kafrawy, S.B., and Taha, M.M.N., 2014. Monitoring coastal changes along Damietta promontory and the barrier beach toward Port Said east of the Nile Delta, Egypt. Journal of Coastal Research, 30(5), 993-1005. Coconut Creek (Florida), ISSN 0749-0208.
Monitoring Coastal Changes along Damietta Promontory
El-Asmar, H.M.; El-Kafrawy, S.B., and Taha, M.M.N., 0000. Monitoring coastal changes along Damietta promontory and the barrier beach toward Port Said east of the Nile Delta, Egypt. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208.
The coastline of the Nile Delta experienced accelerated erosion since the construction of the Aswan High Dam in 1964 and, consequently, the entrapment of a large amount of river sediments behind it. The coastline of the Rosetta promontory showed the highest erosion in the Delta with an average retreat rate of 137.4 m year −1. In 1991, in an effort to mitigate sediment loss, a 4.85 km long seawall was built on the outer margin of the promontory. For additional beach protection, 15 groins were constructed along the eastern and western sides of the seawall in 2003 and 2005. To quantify erosion and accretion patterns along the Rosetta promontory, 11 Landsat images acquired at unequal intervals during a 40 year time span (1972 and 2012) were analyzed. The positions of shorelines were automatically extracted from satellite imagery and compared with three very high resolution QuickBird and WorldView2 images for data validation. Analysis of the rates of shoreline change revealed that the construction of the seawall was largely successful in halting the recession along the tip of the promontory, which lost 10.8 km 2 prior to coastal protection. Conversely, the construction of the 15 groins has negatively affected the coastal morphology of the promontory and caused a reversal from accretion to fast erosion along the promontory leeside, where some segments of the shoreline have undergone as much as 30.8 m year −1 of erosion. Without hard structures, the tip of the Rosetta promontory would have retreated 2.3 km by 2013 and lost 7.2 km 2 of land. About 10% of this land is deltaic fertile cultivated farms. Moreover, without additional protection the sides of the promontory will lose about 1.3 km 2 of land and the coastline would recede at an average rate of 200 m by 2020. Unless action is taken, coastal erosion, enhanced by rising sea level, will steadily eat away the Nile Delta at an alarming rate. The successful demonstration of the advocated procedures in this study could be adopted, with appropriate modifications, for other deltas worldwide.
Environmentally-Friendly Proposals for Coastal Stability at Rosetta Promontory, Nile Delta
The coastal zone of Nile Delta Coast is a dynamic system which was in equilibrium or experienced huge amounts of sediment transported with the water discharges transfer from Nile branches to the Mediterranean Sea. A remarkable decrease in the sediment discharges arises with the construction of barrages, low Aswan dam, and Aswan High Dam south of the Nile river at beginning of the 20th century which trapped almost all the flood sediments behind. Consequently, the coastal zone has suffered from shoreline erosion, particularly at Rosetta, El Burullus, and Damietta. Not only erosion is the main challenge facing this coastal zones, but also, siltation inside the inlets discharge to the sea. A depth-averaged model has been used after calibration and validation, to study morphological changes around the nourishment area at Rosetta promontory, and testing the validity of some alternatives proposed to mitigate the outlet problems. Among these alternatives: diversion of side channel from the sea to the Nile River, and finally, the sand motor technique. The aim of this paper is to test different proposed alternatives and analyze it in terms of morph-dynamic processes to reach an applicable solution for the instability of the promontory.
Nile Delta Shoreline Changes: Aerial Photographic Study of a 28-Year Period
1988
Airphotographic analysis is used to detect erosional and accretionary changes, and to define coastal features along some stretches of the Nile Delta coast of Egypt. Two series of aerial photographs, taken in 1955 and 1983, were applied to three unstable coastal zones: the Rosetta and Damietta promontories, and the Burullus-Baltim sector. Comparison of the two successive photo surveys serve to monitor the impact of the Nile River control and the coastal dynamic regime. The study reveals that the outer margin of both Rosetta and Damietta promontories seem to be the most eroded areas. These promontories are retreating due to the cut off the sediment supply after damming the river. The estimated highest rate of erosion during the 28-year period is: 114,9 and 31 m/yr respectively, at Rosetta, Baltim and Damietta sectors. Remarkable accretionary patterns are also coupled with shoreline erosion, as has been noticed on the eastern side of the two promontories, and to the west of Burullus inlet. Moreover, photographic analysis helps to detect some salient coastal features such as the ancient coastal sand ridges east of the Rosetta and Damietta promontories, and a distinct spit southeast of the Damietta promontory. The prevailing eastward longshore drift of sediments from the adjacent beaches associated with the strong decrease of sediment supply from the Nile River upon completion of the Aswan High Dam in 1964 are responsible for the detected erosional and accretionary phenomena along the three study areas.
Human-induced changes in the geomorphology of the northeastern coast of the Nile delta, Egypt
Geomorphology, 2009
Landsat Enhanced Thematic Mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and field observations were used to interpret geomorphological changes in the coastal zone between Kitchener drain and Damietta spit in the northeastern Nile delta previously recognized as a vulnerable zone to the effects of any sea-level rise resulting from global warming. The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers. Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km 2 to the agricultural deltaic land. About 48 km 2 of sand dunes, marshes, sabkhas and salt pans have been converted to productive fish farms. The main urban centers have expanded, and new urban centers (Damietta harbor and the New Damietta city) have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As the consequence of human activities the size of Manzala lagoon has been reduced to less than 50%. Short-term shoreline changes along the coast of the study area established from beach profile survey, spanning the years of 1990 to 2000, reveal longshore patterns of erosion versus accretion. The rate of shoreline retreat has increased in the downdrift side of Damietta harbor (- 14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of Ras El Bar detached breakwater system, with a maximum shoreline advance of ~ 15 m/year. A sandy spit, 12 km long, has developed southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore currents and sediment transport, in addition, the impact of man-made coastal protection structures.