Assessment of a Combination Between Hard Structures and Sand Nourishment Eastern of Damietta Harbor Using Numerical Modeling
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Alexandria Engineering Journal (2017) xxx, xxx–xxx HOSTED BY Alexandria University Alexandria Engineering Journal www.elsevier.com/locate/aej www.sciencedirect.com ORIGINAL ARTICLE Assessment of a combination between hard structures and sand nourishment eastern of Damietta harbor using numerical modeling A.M. Khalifa a,*, M.R. Soliman b,c, A.A. Yassin b a CoRI, Alexandria, Egypt b Faculty of Engineering, Alexandria University, Alexandria, Egypt c College of Engineering, Arab Academy for Science, Technology & Maritime Transport, Egypt Received 17 December 2016; revised 13 April 2017; accepted 18 April 2017 KEYWORDS Abstract Damietta harbor was constructed in 1982 as an inland harbor with its 15 m depth nav- Numerical modeling; igation channel and two jetties acting like an obstacle to not allow sediment deposition in the har- Damietta harbor; bor. On the other hand, they significantly affect the northern coast shoreline and hinder the Egyptian shoreline changes; sediment circulation in Damietta promontory. Satellite images show that new headlands are being Inland harbor implemented in the coastal shores of As-senaneyah. The proposed project consists of implementa- tion of four headlands with length of 160 m, spacing of 400 m and using 150,000 m3 nourishment in those spacing between the hard structures only once during the construction time. Litpack 1D- model is used to predict shoreline responses to number of different five scenarios considered as com- bination between hard structures such as headlands and sand nourishment. A total number of 32 profiles were used to assess the shoreline changes along Gamasa, Damietta and Ras El-bar resort from 2010 to 2015. This study prevails a high erosion rate of the eastern and western shorelines of the proposed headlands. Nourishment of 200,000 m3/year is found to be a reasonable solution due to simplicity of being attained from Damietta harbor’s annual dredged materials which was reported to be average of 1 million m3/year. Ó 2017 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction a new inland harbor of Damietta shown in Fig. 1A [3]. The construction of the harbor, especially its jetties is considered Along northern coasts of Egypt, shoreline changes are found as a sediment trap which hinders natural circulation of sedi- to be high due to harbor construction and shore protection ment along east part of the Nile delta. Sogreah (1982) had pre- structures [1,2]. In 1982, a conclusion was made to construct dicted erosion east of the harbor and is definite that the effect would be most severe for a distance of 500–1000 m along the shoreline [4]. El.Asmar (2002) results show that significant * Corresponding author. E-mail address: [email protected] (A.M. Khalifa). amounts of erosion could be detected using Remote sensing Peer review under responsibility of Faculty of Engineering, Alexandria method for some 6.2 km beyond the eastern jetty, toward the University. coastal resort of Ras El-Bar [5]. El.Asmar (2002) prescribed http://dx.doi.org/10.1016/j.aej.2017.04.009 1110-0168 Ó 2017 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article in press as: A.M. Khalifa et al., Assessment of a combination between hard structures and sand nourishment eastern of Damietta harbor using numerical modeling, Alexandria Eng. J. (2017), http://dx.doi.org/10.1016/j.aej.2017.04.009 2 A.M. Khalifa et al. Figure 1 (A) Layout of study area including Damietta harbor and protection structures and (B) wave gauge station location and wave rose measured in the study area in 2010. that 10.5 km of shoreline would be affected due to the harbor 2. Study area construction [5]. These results indicate that the impact of har- bor construction on the Nile Delta shoreline has affected a lar- The study area was assessed by 32 bathymetric profiles surveyed ger area than that predicted by Sogreah (1982) at the time of by CoRI reaching the 8 m depth with average length of 1 km for construction [4]. A retreat of the shoreline is documented five continuous years [10]. Fig. 2 represents the average shoreline about 5 m/year at Ras El-Bar resort [6,7]. Fig. 1A shows the change rate/year through analyzing surveyed shorelines from study area representing 5.5 km western of Damietta harbor 2010 to 2015 with total of 32 profiles distributed on a distance and 9.5 km western of the harbor including the 9 detached of 15 km along Gamasa, Damietta and Ras El-Bar shores. breakwaters and extending to the western jetty of Damietta The data reveal an accretion pattern western of the harbor with promontory which can be assumed as a closed boundary for values range from 10 to 20 m/year over distance of 3 km while an the sediment movement. Ras El-bar nearshore region showed erosive pattern can be determined on the eastern side of the har- continuous deepening of the water depth and steepening of bor with values range from À5toÀ8 m/year over distance of its underwater shore slope. Through the period from 1986 to 3 km. Shoreline bounded with the detached breakwaters can 2000 a series of eight detached breakwaters 200 m in length be observed to have salient phenomenon with an average with 200 m spaces in between were constructed to protect the advancing shoreline of 4 m/year [10]. western side of Damietta promontory along a distance of Wave data in 2010 for a full year were recorded by a current 3km[8]. Salient has already been noticed along the shores of and wave gauge S4DW deployed near the bottom (0.5 m above Ras El-Bar; however, erosion pattern was highly perceived sea bottom) at the western side of the navigation channel of the for the distance of 4 km bounded by the detached breakwaters harbor at a water depth of 12 m and the wave rose was con- in the east and the eastern jetty of Damietta harbor in the west. cluded as shown in Fig. 1B. The wave rose shows that Maxi- Ongoing research pursues using Numerical modeling simu- mum wave height during the strongest storms is almost lations for this classic case of erosion caused by artificial 6.0 m, while significant wave height is 4.2 m from N (January human interference responding to littoral obstacle in the exis- 2010). Wave period is 8 sec for 98.2% of the time (60.4% of tence of natural longshore sediment transport. Thus, this paper the time between 7 and 8 sec). The monthly maximum peak presents a methodology to assess and evaluate number of com- wave period fluctuates between 7.0 and 13.2 sec. The predom- binations between nourishments along with hard structures inant wave direction throughout is from the N-NW (86%) using numerical modeling [9]. Please cite this article in press as: A.M. Khalifa et al., Assessment of a combination between hard structures and sand nourishment eastern of Damietta harbor using numerical modeling, Alexandria Eng. J. (2017), http://dx.doi.org/10.1016/j.aej.2017.04.009 Assessment of a combination between hard structures and sand nourishment eastern of Damietta harbor 3 Figure 2 Average shoreline changing rates per year. Figure 3 Litpack 1D-Model setup. sector for all months (mainly from NNW (49%) direction). A Full year wave data of 2010 and measured tidal data were used significant spread of wave energy occurs for western waves to simulate the natural coastal condition in the study area. The (NNW, NW and WNW) at about 25–35 km east of Damietta model covers the study area and extends 6 km east from Dami- promontory mouth as discussed by A.Abo ZED [11]. etta harbor and 9 km to the west reaching the western jetty of Damietta promontory which considered the eastern boundary 3. Numerical model development of the model. Fig. 3 presents the study area with the included structures as breakwaters, Damietta seawall, two harbor jetties Litpack [12] 1D-Model was applied to simulate shoreline and two groins in the west of the seawall. Measured 2014 changing in the study area to assess the combination between shoreline was used as the initial condition of the model. The hard structures and nourishment in order to solve the problem harbor’s jetties were defined as two jetties with perpendicular of obvious erosion in the beaches eastern of Damietta harbor. alignment with the baseline which is assumed to be horizontal Please cite this article in press as: A.M. Khalifa et al., Assessment of a combination between hard structures and sand nourishment eastern of Damietta harbor using numerical modeling, Alexandria Eng. J. (2017), http://dx.doi.org/10.1016/j.aej.2017.04.009 4 A.M. Khalifa et al. Figure 4 Calibration process dividing the model domain into three parts 5000 m for each shown as (A) represents first 5 km, (B) represents second 5 km and (C) represents last 5 km of the model. as simplified as shown in the figure. Eight profiles were used to surveyed 2014 shoreline [10] as an initial shoreline and 2015 simulate the varieties in bathymetry along the study area. shoreline [10] which is compared with the model predicted shoreline. The used calibration parameters are active depth 4. Preliminary results which defines closure depth in the study area assumed to be 12 m along the study area, extension of the sediment transport 4.1.