Space-borne technology for monitoring temporal changes along Damietta shoreline, Northern Egypt

In this research, remote sensing and GIS techniques were employed to monitor and quantify annual changes along Damietta shoreline, Egypt. Coastal landforms are highly dynamic in nature; however urbanization and population rapidly increase on these areas due to the abundant natural resources. A set of Landsat and SPOT multispectral images acquired at different dates (i.e. TM.1984, SPOT3 1997, SPOT4 2011 and OLI 2014) were used to monitor the shoreline changes. Onscreen digitizing was simply used for shoreline mapping at different years, using ArcGIS software V 10.1. Conversion of polyline into polygon was utilized in order to calculate areas characterized by erosion and accretion. The results showed that the study area was subjected to remarkable and non-expected changes during the study periods. Recorded eroded and accreted areas were 6.993 and 4.429 km2, respectively during 1984-1997, 8.111 and 3.283 km2 during 1997-2011 as well as 1.242 and 3.455 km2 during 2011- 2014. The annual rate of erosion during the periods of study showed relatively similar values recording 0.538, 0.579 and 0.414 km2 at 1984-1997, 1997-2011 and 2011-2014, respectively. However, the annual rate of accretion recorded the maximum value at 2011-2014 (1.152 km2/year), while the minimum rate was remarked at 2011-2014 (0.234 km2/year) followed by 0.341 km2 at 1997-2011. The study recorded that the construction of breakwater in the study area has decreased the annual rate of erosion particularly from the period of 1997-2011 to 2011-2014 (i.e. from 0.579 km2 to 0.414 km2, respectively). This decrease was synchronized with an increase in the annual accreted areas from 0.234 km2 to 1.152 km2, respectively. Due to the shoreline dynamism, the constructed breakwaters have created new areas of erosion which were responsible for drowning deaths of about 75 swimmers.