Assessment of coastal changes along Baltim resort (Egypt) using remote sensing and DSAS method

Abstract

Baltim resort has exposed to severe erosion due to critical natural factors, especially after the establishment of Aswan High Dam. The number of detached breakwater along Baltim resort is 14 detached breakwaters; nine of them were constructed in the period (1993-2002). The other 5 segments were constructed in the period after 2003 with the same dimensions; in addition, 9 short groins were constructed on the west of Kitchener drain). The present study was conducted to evaluate the recent shoreline sedimentation patterns and to determine whether the implemented detached breakwater systems along Baltim resort have affected that patterns or not. Quality assessment through quantitative method has been used to validate the used data, since the used images in this research are from 4 different satellite sensors; where the special and spectral resolutions are not equal. In this study, the behavior of Baltim resort's coastline was analyzed after the construction of the detached breakwaters #9 to #14, to determine whether the general erosion/ accretion pattern along the resort has been reshaped or not. Shoreline change detection was calculated using the Digital Shoreline Analysis System (DSAS). The rate of shoreline change was estimated from three statistical models of DSAS: Linear Regression Rate (LRR), End Point Rate (EPR) and Least Median of Square (LMS). Accretion in the form of tombolo between breakwaters #9 to 14 is found out to be very high with a maximum value reached ~ +32.4 m/yr, which recorded in front of breakwater #11, followed to the east by down-drift erosion that reached its maximum rate value to be ~ -34 m/y in front of the 9 groins west of Kitchener drain. At the east of Kitchener drain severe erosion happened to a distance of 5.7 km and after that distance, the shoreline is almost stable and this pattern matches with the calculated alongshore rate of shoreline changes of the present study.