Original article

Environmental impacts of El Arish power plant on the Mediterranean coast of Sinai, Egypt O.E. Frihy Æ A.A. Badr Æ M.A. Selim Æ W.R. El Sayed

Abstract A monitoring program was undertaken to evaluate the adverse impacts of the El Arish power plant on the northeastern Sinai coast of Egypt. This program spanned 28 months and includes intensive hydrographic surveying, measurements of waves, longshore current, littoral drift, currents behind the breaker zone, offshore currents, sea-level variation and water quality. The shoreline dynamics of the region have been substantially disrupted due to the high-intensity longshore transport and the interruption of longshore transport by the shoreperpendicular intake breakwaters. Maximum erosion of 5.5 m/year has been documented east of the breakwater. This erosion has been continuing eastwards, threatening the resort centers on the downcoast beaches. On the other hand, accretion (11.7 m/year) is recorded along the western side of the breakwater, accumulating great volumes of sand which is transported to the east by littoral currents. Part of this sand enters the intake basin, causing sedimentation problems by the easterly and westerly littoral drifts and cross-shore currents. In other respect, an unprotected offshore channel dredged in front of the water discharger, east of the intake, acts as an effective trap for the predominantly easterly sand drift, subsequently interrupting sediments moving from the east, accelerating processes of erosion to the east. The cooling and wastewater discharging from the discharger to the sea are insignificantly warmer than the upcoast water and not contaminated with chemical wastes. The thermal and chemical plume has no significant effect on the quality of the coastal water in the region. Keywords El Arish power plant Æ Egypt Æ Mediterranean Sea Æ Sinai coast

Received: 28 October 2001 / Accepted: 30 January 2002 Published online: 4 April 2002 ª Springer-Verlag 2002 O.E. Frihy (&) Æ A.A. Badr Æ M.A. Selim Æ W.R.E. Sayed Coastal Research Institute, 15 El Pharaana Street, 21514 Alexandria, Egypt E-mail: [email protected]

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Water intake Æ ater quality Æ Basin sedimentation Æ Beach erosion Æ Wave climate

Introduction Main environmental problems resulting from vaporous power plants are shoaling of the water intake basin, disrupting the coastline stability, and changing the water quality of the surrounding ecosystem. In 1993, a power plant located in the El Masaid area, 10 km west of El Arish on the coast of the Sinai Peninsula, was constructed to meet the demands for coastal development of the region (Fig. 1a). As for any power plant, seawater is continuously withdraw from a water intake basin for cooling and watervapor operations. Inversely, the ex-cooling and treated wastewaters are outflowing to the sea through a discharger. Initially in 1994, a water intake was constructed with no protection, followed by a water discharger located about 500 m east of the water intake (Fig. 1b inset). The power plant was built inland south of these structures. The main building of the plant consists of two oil-fired steam burners with two 80-m-heigh chimneys, generating 60 MW, and a wastewater treatment unit. Over time, the unprotected water intake led to sedimentation and subsequently two breakwaters were constructed to mitigate this problem (Fig. 1b, inset map). The western breakwater curves about 135 m offshore whereas the eastern one is approximately 60 m long, perpendicular to the shoreline. They leave an inlet about 25 m wide to feed the intake by seawater, at 5-m water depth. The breakwater crests have a maximum elevation of 3.5 m above mean sea level and a sea-face slope of 1:2. The armor layer of the breakwaters is built from dolomitic limestone blocks ranging from 0.5 to 2.5 tons. Following construction of the eastern breakwater in March 1995, immediately after 4 months, the coastline behaves in a state of instability. Significant erosion has been observed east of the intake whereas sand accretion occurred upcoast. Part of this sand bypassed to the intake, causing sedimentation problems (Anonymous 1996). Many worldwide examples are known where breakwaters or jetties block a net littoral drift of sand along the beach, thereby producing a shoreline advance on the updrift side and erosion downdrift of the shore-parallel structures (Komar 1976; Leatherman 1991).

DOI 10.1007/s00254-002-0563-6

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sources and sinks. The principal sources of sediment for each littoral subcell are the eroded promontories and protruding Bardawil barrier which supply large quantities of sand. The eroded sand is transported along the coast by waves and currents until it is intercepted and terminated in the downcoast direction by adjacent sinks including promontory saddles, embayments and long breakwaters. Of particular importance to this study is the Bardawil subcell, which consists mainly of the arcuate bulge of the central Bardawil region (Fig. 1a). In this subcell, sand eroded from the relict Bardawil bulge barrier and coastal dunes is transported downcoast to the east and southwest, resulting in accretion along the El Arish embayment, including the power-plant coastline. For the most part, this sand is wave-driven by eastward littoral currents and currents generated by the east Mediterranean gyre which sweep across the inner shelf (Inman and Jenkins 1984; Stanley 1989). The coastline of the Sinai is of typical microtidal semi-diurnal nature. Recorded daily water-level variations measured from the mean sea level in the study area reveal a mean high-water level and a mean low-water level of 20.22 and –11.01 cm, respectively, with a tidal range of 31.23 cm (this study). The main objective of this paper is to assess coastal impacts induced from implementing the El Arish power plant. These include the effects of the intake breakwaters on coastline stability, sedimentation of the intake basin, and thermal and chemical pollution of the water outflowing from the plant discharger. Understanding the Fig. 1 a Generalized map of the northern Sinai and the northeastern part of hydrodynamic forces controlling the processes of sedimentation of the intake and beach erosion downdrift the Nile delta, showing the large-scale coastal erosion/accretion patterns and sediment transport direction (modified from Frihy and of the intake jetties could assist in the formulation for Lotfy 1997). b The coastline of El Arish power plant in the overcoming negative impacts.

northeastern Sinai of Egypt, showing the positions of 42 beach profile lines examined in this study. Positions of wave, littoral current and littoral drift measurement stations are denoted by symbols. Depth contours are in meters

Sedimentation of water intakes or similar harbor basin structures is a worldwide problem and has been investigated by others. Among these studies are the entrance of Point Spain Harbor, Canada (Pratte et al. 1982), the entrance of the Taito and Katagai fishery harbors, Japan (Sasaki and Sakuramoto 1984), the entrance of Batabano Port, Cuba (Garcia 1999), the water basin of the Koeberg nuclear power station, South Africa (Prestedge and Fleming 1999), and the entrances of Sidi Kerair Marina and Damietta Harbor, Egypt (Frihy 2001). In view of the large-scale sedimentation pattern of the Sinai coast, the study area lies within the Bardawil subcell. Frihy et al. (1991) and Frihy and Lotfy (1997) have identified a series of self-contained subcells along the nearshore zone of the Nile delta and Sinai coast, based on the general erosion/ accretion patterns, wave refraction pattern, as well as multiple geomorphologic and petrologic indicators. These subcells are part of the regional Nile littoral cells extending from Alexandria to Akko in the northern part of Haifa Bay, Israel (Inman and Jenkins 1984). Each delta subcell contains a complete cycle of littoral transportation and sedimentation, including

Materials and methods A monitoring program was undertaken to evaluate hydrodynamic forces affecting the sedimentation pattern of the nearshore area as well as the water quality off El Arish power plant. The monitoring program spanned approximately 28 months, from March 1996 through to June 1998. This program includes hydrographic beach profile surveys, currents, littoral drift experiments, sea-level variations, grain-size analysis of beach and nearshore profile samples, and water quality assessment (Fig. 1b). The monitoring area extends 6.1 km along a portion of the shoreline hosting the power plant and approximately 1,000 m offshore. Locations of field activities are graphically symbolized in Fig. 1b. A total of 42 beach-nearshore profiles (up to 10-m water depth or to an offshore distance of 1,000 m from the baseline) was surveyed throughout the study area. They are inter connected by a baseline fixed along the study area. The orientation of the profile lines is approximately perpendicular to the coastline. The spacing between adjacent profiles varied between 50 and 500 m, depending on the geomorphology of the shoreline. More closely spaced profiles were localized on either side of the breakwaters (Fig. 1b). Profiles are numbered 1 through 42

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from west to east. Soundings were taken every 10 m from the baseline to a maximum distance of 250 m seawards from the baseline (reference mark) to precisely record seafloor changes in the surf zone. Seawards of this point, seafloor soundings were measured every 50 m to a water depth of approximately 10 m. The soundings and inshore leveling of the profiles were surveyed with the use of an echosounder, theodolite, GPS and rubber boat. Soundings and leveling were referenced with respect to the mean sea level. Beach profiles were surveyed 5 times from March 1996 to June 1998. A total of 198 bottom samples were collected using a grab sampler every 100 m along 20 selected profiles lines during the 5th survey (December 1997–June 1998). Beach samples (42 samples) were also collected along each of these profiles (Fig. 1b). In the laboratory, grain-size analysis was completed by a standard ro-tap sieving system using one-phi sieve intervals. The mean grain size (Mz) for each sample was calculated using the formula of Folk and Ward (1957). The resulting values of Mz in phi units were converted to millimeters according to the phi–mm transformation: (Mz mm)=1/2/. The wave regime was analyzed for this study based on measurements taken by a pressure S4DW wave/current gauge installed approximately 1,200 m on the western side of the Damietta promontory, i.e., in about 12-m water depth (Fig. 1a). The wave gauge recorded the directional wave and current spectrum for 20 min every 4 h. Wave results were compiled for 16 months for the following periods: 1997 (October, November and December), 1998 (January, May, June, August, September, October and November), and 1999 (January, February, March, April, May and June). Data obtained from the wave gauge are transferred to the PC computer and analyzed to determine wave height, wave period and wave direction, using dedicated software. Magnitude and direction of the currents beyond the breaker zone were measured along study profiles at 200-m intervals in up to 10-m water depths (Fig. 1b). Current reading spanned approximately 10 min at each station. Measurements were taken simultaneously during the profile surveys using a direct-reading current meter (CM-2). At each station, three measurements were taken: near the surface, at mid-depth, and near the bottom. Daily longshore current speed and direction were measured at five stations, two on the western side of the intake basin at profile numbers 2 and 17, two on the eastern side of the discharger at profile numbers 26 and 41, and one between the intake basin and the discharger at profile number 22 (Fig. 1b). Longshore current measurements were taken during the whole period March 1996 to June 1998. Current measurements were obtained inside the surf zone, in water depths ranging from 1.2 to 1.5 m, by following the movement of a float (buoy) and measuring the time it takes to travel a distance of 20 m in the longshore direction. Measurements of current speed and direction were taken twice daily, once in the morning and again in the afternoon.

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Littoral drift was determined using the field and laboratory approach of Ingle (1966). Drift rates in the surface zone were measured at 3 sites, at the western side of the intake, between the intake and the discharger, and on the eastern side of the discharger (Fig. 1b). Near-surface water samples were taken at 0.5 m below the water surface to avoid floating matter. Samples were taken by Nansen bottle along profiles at 200-, 500- and 1,000-m distance from the baseline (Fig. 1b). Water temperature, pH, and DO were measured in situ using a reversing thermometer, portable pH meter and portable DO meter, respectively. The collected samples were stored with great care using a special method until further analysis in the laboratory. Ammonium was determined firstly following the indophenol blue method (IOC 1983). Total suspended solid was determined in 5-l seawater samples using 0.45lm GF/C Whatman filters. Nitrite and nitrate were determined in filtered seawater samples, by using 0.45-lm membrane filters, following the approaches of Strickland and Parsons (1975). Total phosphorous was determined in unfiltered seawater samples according to Valderrama (1981).

Results and discussion Wave climate Typically, waves are the most energetic forcing agent acting in the coastal zone. This is particularly true for Mediterranean coastal environments, which are classified as wave-dominated following the criteria described by Davis and Hayes (1984). Wave action along the Mediterranean coast of Egypt is seasonal in intensity and direction, and is strongly related to large-scale pressure systems over the Mediterranean and the north Atlantic (Hamed 1983; Nafaa et al. 1991). Accordingly, they have indicated that wave climate was divided into three seasons. Winter extends from November to March, spring from April to May, and summer from June to September. A wave rose averaging the 16-month period is depicted in Fig. 2a. Data examined in this study show low-swell waves prevailing during spring and summer, with wave heights rarely exceeding 1–1.5 m for waves blown from the WNW and rarely from the NE. Winter waves are much higher than summer waves, fluctuating between stormy and calm intervals and coming from the N, NNW and NW sectors. These are the predominant cause of morphological changes (Fig. 2a). In order to analyze beach changes, the relationships between incoming waves and shoreline orientation are incorporated. Applying the guidelines given in Mangor (2001), the relationship between wave climate and the present shoreline orientation, 80 to the north, provides an oblique wave exposure presented schematically in Fig. 2a. Two main wave component groups are responsible for generating easterly and westerly sediment transport (see the two arches in Fig. 2a). Accordingly, the predominant wave directions (NNW, NW and WNW, totaling 69%) are responsible for the generation of longshore currents

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that direction. Owing to the general shoreline orientation (80 to the north) and wave climate, easterly longshore currents are expected to be induced from waves approaching the study area from the NNW, NW and WNW (Fig. 2a, b). This is confirmed by the measured longshore currents on both sides of the power-plant coastline. During the entire period, measured longshore current showed that the predominant longshore current direction is from west to east (62–65%), induced from waves coming from the NNW and NW. On the other hand, west-directed longshore currents (24–29%) result from the remaining wave component from the N, NNE and NE sectors, particularly during March and April due to easterly winds. The effect of the western breakwater of the intake has been diminished due to reaching full capacity of deposition on its western side. Therefore, the sediments moving alongshore by littoral currents began to bypass and go around the tip of the eastern breakwater and enter the inlet of the intake basin, causing sedimentation. The easterly current together with the reversibly west-directed current (25%), recorded between the water intake and the discharger, are acting to accelerate the processes of sedimentation in the intake basin.

Fig. 2a–c The littoral zone of El Arish power plant area. a Wave distribution (wave rose along with the average orientation of the present coast and the two wave exposures denoted by arches). b Near-surface currents. c Bottom currents along with littoral transport rates (littoral drift)

towards the east due to northwest winds. This is in addition to small percentages from the N, NNE and NE sectors which generate a reverse longshore current towards the west, particularly during March and April, totaling 29% (Fig. 2a). The remaining insignificant frequency (2%) represents calm conditions, generally for waves approaching from land, i.e., from SW and SE quadrants. On the whole, the average wave height and period are 0.5 m and 6.3 s, respectively. Generally, the recorded average wave direction-height distribution revealed that the frequency distribution of wave height between 0.5 and 1.0 m is more dominant than others between 1- and 2-m heights (Fig. 2a).

Currents beyond the breaker zone The overall current patterns beyond the breaker zone measured under the prevailing wave conditions are illustrated in Fig. 2b, c. The overall directions of surface and bottom currents are more or less similar, since they were measured during the prevailing north/northwest winds. Currents are generally towards the east and obliquely trending offshore, i.e., heading ENE. A few current measurements have a tendency to onshore. Bottom currents between the intake and the discharger show directions towards the southwest, which may transport sediments to the intake basin (Fig. 2c). Maximum current velocity is 20 and 15 cm/s at the surface and near the bottom, respectively. In general, the spatial distribution of current patterns beyond the breaker zone is directed to the east, offshore and onshore (Fig. 2b). The resulting patterns agree quite well with the regional longshore transport model reported by Goldsmith and Golik (1980) in this region. Waves approaching the El Arish–Rafah area transport high volumes of sediment to the northeast due to the very large angle between wave crest and shoreline orientation.

Littoral drift Due to the general coast orientation, the longshore sand transport is almost unidirectionally eastwards all year long, with small westerly reversals. Waves with a high angle of attack drive an intense longshore transport rate of sand as high as 0.710·106 m3/year. Annual drift rates in the surface zone measured by fluorescent sand traces on the western side of the intake, between intake and disLongshore current The dominant coastal process, or mechanism, for moving charger, and on the eastern side of the discharger were found to be 0.49·106, 0.56·106 and 0.71·106 m3/year, sand in the littoral system of the study area is the longrespectively. Values of littoral drift and their percentage shore sand transport. Longshore sand transport is the wave-driven movement of sand along the coast. As waves occurrence from different directions are depicted in approach a beach at an angle, they break and move sand in Fig. 2c. These results are comparable with the net

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sediment transport rates (450,000 m3/year) reported by Inman et al. (1976) in the vicinity west of El Arish beach. Their estimation was based on aerial photographs of trapped sand on the western side of the Bardawil lagoon inlet jetties. Offshore profile survey Data obtained from beach profiles which extended to 10-m water depth, corresponding to about 1,000 m, provide information to determine bathymetry, beach gradient, change in shoreline positions and seabed level, and volumetric analysis of sediment. Generally, seafloor contours of the nearshore study zone are nearly parallel to the coastline, with no dominant seabed features. Beach-nearshore slopes generally have two main slope gradients. An inner, relatively steep slope (1:50) extends offshore, followed by an outer gentle slope of 1:600. Generally, the inner slope part terminated at about 8-m water depth along the study coastline. The shoreline of the study area is typically a straight, smooth sandy beach oriented more or less in a west-east trend. Superimposed zero-contour line ‘‘shorelines’’ of January 1992 and May 1998 depict shoreline changes in the study area (Fig. 3a). The shoreline position of January 1992 was measured by the client prior to designing the breakwater intake. During this period (6.4 years), significant seaward advance of the shoreline (75 m, i.e., 11.7 m/year) is measured immediately west of the eastern breakwater at profile 18. Conversely, erosion prevails downcoast, attaining a maximum (35 m, i.e., 5.5 m/year) 140 m east of the discharger between profiles 27 and 28. The pattern of shoreline changes in the study area mainly resulted from the prevailing easterly littoral current. Seafloor changes relative to mean sea level (MSL) for the beach-nearshore profile survey between March 1996 and June 1998 across the study area are shown in Fig. 3b. The computer-generated spatial interpolation of verticalchange values reveals areas of erosion and accretion on both sides of the intake breakwater. However, upcoast areas west of the intake up to 6-m water depth show a tendency to accretion (0 to 2.5 m). Conversely, in the same depth zone, erosion associated with accretion exists downcoast east of the breakwater (0.0 to –2.5 m). Significant local accretion (1.5–2.5 m) occurs in the vicinity of the water intake. The deeper zone from 6 to 10 m shows an erosional pattern (–0.5 to –2.5 m) over the study period. The identified spatial distributions of erosion and accretion reflect the patterns of longshore and offshore currents present throughout the study area. Net volumetric changes of sediments per meter (m3/m) were determined for beach profile data along the entire length of the study area (Fig. 3c). Calculations are performed between successive surveys for the 42 profiles during the period March 1996 to June 1998. Of the six periods, three indicate net sediment accretion upcoast of the water intake (maximum 486 m3/m). On the other hand, erosion is dominant along the eastern coast (maximum –329 m3/m). The volume change in the area between the intake and discharger is mostly fluctuating between –620 and 624 m3/m. The fluctuation of accretion 608

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Fig. 3a–d El Arish power plant coast. a Shoreline changes depicting prebreakwater shoreline (January 1992) and post-breakwater shoreline (May 1998). b Patterns of erosion and deposition on the littoral zone, as deduced from the vertical changes in the seabed between profiles surveyed in March 1996 and June 1998. c Longshore distribution of volumetric changes per unit beach length over the monitoring periods between April 1969 and May 1998. d Spatial pattern of mean grain size of beach and bottom sediments. Depth contours are in meters

and erosion periods indicates that changes in sand volume are independent with time, since profile assessments were carried out seasonally in spring, winter and summer. Grain-size distribution The beach and littoral sediments of the north Sinai are derived from eroded beaches and the inner shelf of the Nile delta by eastward littoral currents and currents generated by the east Mediterranean gyre (Inman and Jenkins 1984; Stanley 1989). Medium and fine sand occur in the beach area (Mz=0.24 to 0.48 mm), whereas very fine sand and coarse silt cover the nearshore zone (Mz=0.06 to 0.13 mm). Alongshore variations in the mean grain size show that coastal sediments are nearly coarser along the

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stretch west of the intake which is characterized by accumulation of sand (average Mz=0.26 mm), becoming slightly finer in the eroded downcoast area between the intake and the end of the study coastline (average Mz=0.22 mm; Fig. 3d). This explains the relatively steeper beach-seabed bottom of the updrift sector, compared to that of the downdrift coast. The cross-shore sediment distribution in the littoral zone commonly shows a fining trend offshore. This pattern is mainly caused by a shoreward increase of energy of waves and current-driven sediment transport processes. Some patches of coarse sand with a mean grain size of 0.48 mm occur locally in front of the resort centers east of the power plant. This is due to local nourishment operations taking place in front of these resort centers, resulting from the blocking of sand transport by the power-plant jetties. The gradient in grain-size distribution in the cross-shore and alongshore directions is related to interactions between the different transport processes and grain sorting. Water quality Results obtained from the analysis of water samples collected off the study area are spatially distributed as isopleths in Fig. 4. In order to detect the effect of water discharging from the power plant, a comparison was made between measurements of selected parameters of updischarger water in the western most part of the study area and water fronting the discharge (Table 1). Areas of concentration and diminution of these parameters are dispersed primarily away from water outfalling from the discharger towards the east by both longshore and surface coastal currents (eastward- and seaward-trending currents). Temperature has slightly risen from 16.4 to 17.1 C upcoast and in front of the discharger, respectively. Concentrations of suspended solid (11.58 mg/l), ammonium (1.728) and nitrate (0.456 lmol) showed relatively high

concentrations in water fronting the discharger (Fig. 4d–f). Inversely, this area has relatively low values of pH (8.21), dissolved oxygen (6.95 lmol), nitrite (0.03 lmol), and total phosphorous (1.88 lmol; Fig. 4b, c, f, h). In general, the examined data of water quality, whoever, are found to be comparable with those of the surrounding national water, which is not affected by human influences (El Rayis 1973; Morsi 1994; Haslund et al. 1999). This indicates that wastewater treated in the power plant lies within the national standards and its effect on the water quality of the coastal region is insignificant. Mitigation measures Common conventional measures have been widely applied in similar cases to avoid or decrease sedimentation and associated erosional processes resulting from the construction of intake breakwaters. These measures include extension of the breakwaters, changed orientation and shape of the entrance, construction of additional sand trap structures, periodic or permanent dredging, and sand bypassing (Pratte et al. 1982; Sasaki and Sakuramoto 1984; Perillo and Guadrado 1991; Garcia 1999; Prestedge and Fleming 1999; Frihy 2001). In our case study of the El Arish power plant, and following the understanding of coastal processes interacting in this region, adequate alternatives have been considered to mitigate possible sedimentation and beach erosion as well. Temporal mitigation procedures have been undertaken using mechanical trucking of trapped sand west of the intake breakwaters, being placed periodically on the eroded downdrift beaches fronting the recreation centers. On parallel, sand deposited in the intake basin is frequently dredged using a small-scale land-based dredger. These mitigation procedures are temporary solutions but do not totally eliminate possible deposition in the intake basin and erosion of downcoast beaches. In terms of

Fig. 4a–h Isopleth map showing the distributions of a temperature, b pH, c dissolved oxygen, d total suspended solids, e ammonium, f nitrite, g nitrate, and h total phosphorus in the nearshore waters of El Arish power plant. Water depth contours are shown in e

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Table 1 Comparison between levels of hydrochemical parameters measured at the upcoast sites and off the discharger of El Arish power plant

Water quality parameter

Temperature (C) pH Dissolved oxygen (lM/l) Total suspended solids (mg/l) Ammonium (lM/l) Nitrite (lM/l) Nitrate (lM/l) Total phosphorus (lM/l)

permanent mitigation, an additional extension to the existing breakwaters into deeper waters which incorporated minimum sediment movement might mitigate the problem of sedimentation of the intake basin but it will accelerate downcoast beach erosion. Thus, removal of the water intake breakwaters is a possible permanent alternative to alleviate this problem, and it is currently under consideration. Subsequently, these structures would be replaced by using an offshore pipeline system which might be useful in such an active littoral zone. However, the pipeline should be long enough to reach the closure depth, i.e., the water depth of little sediment transport.

Summary and conclusions A field program was carried out to evaluate the impact of El Arish power plant in the northeastern Sinai on the coastal ecosystem. This program spanned 28 months and includes beach-profile surveys supplemented by measurements of waves, littoral currents, littoral drift, currents beyond the breaker zone, and water-level variation. In addition, characteristics of beach, surface bottom sediments and water were investigated. The coastline began to behave in a phase of instability following the construction of the breakwaters of the water intake basin. The eastern breakwater blocked the net littoral drift of sand along the beach, thereby producing a shoreline advance on the updrift side (11.7 m/year) and erosion downdrift of the breakwater (5.5 m/year). The eastern breakwater was not long enough to stop sand bypassing from sand trapped on the updrift side. Sand accumulated on the west side of the breakwater is moved around its tip, and deposited in the intake basin. This sand is originally derived from the eroding Bardawil bulge barrier by the easterly and onoffshore currents. Sediments are dispersed primarily away from sediment sources towards the sink area, including the El Arish coast, by both contour-flowing bottom and cross-shelf (seaward-trending) currents. The sedimentation process is influenced by the temporal variability in the direction and intensity of wave-induced currents, the orientation of the coastline, and the protruding intake breakwaters. Meanwhile, the existing eastern breakwater failed to prevent sand bypassing into the water intake due to its short length versus the high rate of sediment drift.

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Measurements Upcoast/offshore water

Water off the discharger

Average of all measurements

16.4 8.26 7.15 9.65 1.02 0.04 0.337 2.45

17.1 8.21 6.95 11.58 1.728 0.03 0.456 1.88

21.6 8.29 7.15 10.15 1.095 0.336 0.026 2.589

Predominant wave directions are mainly from the NNW and NW, resulting in the generation of longshore currents towards the east due to northwest winds. Currents beyond the surf zone flow to the east and northeast with a tendency to offshore. As a lesson learned, the impacts on the adjacent beaches have resulted from the inadequate designing of breakwaters which, in turn, was based on inefficient local data. The designing of breakwaters as measures to protect the intake against sedimentation did not consider several factors. The power plant is located within a sediment sink area (i.e., convergence area). The nearshore zone is characterized by an active surf zone enriched in fine-grained sand. Littoral drift of sand is relatively high (0.71·106 m3) due to the high angle between wave crest and coastline orientation (50 and 70) for the prevailing NW and NNW waves. Moreover, the significance of the resort beaches located downcoast of the power plant should be also incorporated. In view of water quality, the coastal water of the study area has been insignificantly changed by the water discharged from the power plant. These changes and the slight increase in temperature (0.7 C) indicate that the waters are not polluted, chemically or thermally, due to the regulation control applied in the processes of water treatment of the power plant. Acknowledgements The present investigation was undertaken as part of the Coastal Research Institute program to monitor coastal changes along the full length of the Egyptian Mediterranean coast, and was partially funded by the Egyptian Electric Authority. The authors appreciate the assistance and efforts of the staff of the Coastal Research Institute in the field and laboratory activities of this study. We would like to thank Dr. M.A. Fahmy, National Institute of Oceanography and Fisheries, Egypt for reviewing the water-quality part of this study. The constructive comments and remarks given by the editorial reviewers are much appreciated.

References Anonymous (1996) Progress report on impact of constructing a power plant on El Masaid coastal zone near El Arish, Sinai. Coastal Research Institute, Alexandria Davis RA, Hayes MO (1984) What is a wave-dominated coast? In: Greenwood B, Davis RA Jr (eds) Hydrodynamics and

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sedimentation in wave-dominated coastal environments. Mar Geol 60:313–329 El Rayis OA (1973) Cycle of nutrient salts in the Mediterranean seawater off Alexandria. MSc Thesis, Faculty of Science, Alexandria University Folk RL, Ward WC (1957) Brazos river bar: a study in the significance of grain size parameters. J Sediment Petrol 27:3–27 Frihy OE (2001) The necessity of environmental impact assessment (EIA) in implementing coastal projects: lessons learned from the Egyptian Mediterranean Coast. Ocean Coastal Manage 44:489–516 Frihy OE, Lotfy MF (1997) Shoreline change and beach-sand sorting along the northern Sinai coast of Egypt. Geo-Mar Lett 17:140–146 Frihy OE, Fanos MA, Khafagy AA, Komar PD (1991) Nearshore sediment transport patterns along the Nile Delta Egypt. J Coastal Eng 15:409–429 Garcia AC (1999) Sedimentation control in Batabano port. In: Proc 5th Int Conf Coastal and Port Engineering, Cape Town, vol 3, pp 1899–1908 Goldsmith V, Golik A (1980) Sediment transport model of the southeastern Mediterranean coast. Mar Geol 37:147–157 Hamed AA (1983) Atmospheric circulation features over the southeastern part of the Mediterranean Sea in relation to weather conditions and wind waves along the Egyptian coast. PhD Thesis, Faculty of Science, Alexandria University Haslund OH, Jensen A, Nassr S, Poulsen F, Boisen A, Ebrahim M, El Soeud A, El Raey M, El Shenawy M, El Gamel A (1999) First results from the Egyptian coastal water monitoring programme. In: Proc MEDCOAST 99 Conf, Antalya, Turkey, vol 3, pp 1337–1350 Ingle JC Jr (1966) The movement of beach sand. Developments in Sedimentology Series 5, Elsevier, New York Inman DL, Jenkins SA (1984) The Nile littoral cell and man’s impact on the coastal zone of the southeastern Mediterranean. Scripps Institution of Oceanography Ref Ser 84(31) Inman DL, Aubrey DG, Pawka SS (1976) Application of nearshore processes to the Nile delta. In: UNDP/UNESCO Proc Sem Nile Delta Sedimentology, pp 205–255

IOC (1983) Chemical methods for use in marine environmental monitoring, manuals and guides. Intergovernmental Oceanographic Commission, UNESCO Komar PD (1976) Beach processes and sedimentation. PrenticeHall, Englewood Cliffs, NJ Leatherman SP (1991) Coasts and beaches. In: Kiersch GA (ed) The heritage of engineering geology; the first hundred years. Geol Soc Am Cent Spec Vol 3:183–200 Mangor K (2001) Shoreline management guidelines. Handbook, Delft Hydraulics, Water & Environment Morsi FA (1994) Budget of nutrient salts in the southeastern Mediterranean water off the Egyptian coast. MSc Thesis, Faculty of Science, Alexandria University Nafaa MG, Fanos AM, El Ganainy MA (1991) Characteristics of waves off the Mediterranean coast of Egypt. J Coastal Res 30:25–34 Perillo G, Guadrado G (1991) Geomorphologic evolution of El Toro Channel, Bahia Balanca Estuary (Argentina) prior to dredging. Mar Geol 97:405–412 Pratte BD, Willis DH, Ploeg J (1982) Harbor sedimentation comparison with model. In: Proc 18th Coastal Engineering Conf, ASCE, pp 1119–1126 Prestedge GK, Fleming CA (1999) The cooling water intake for the Koeberg Nuclear Power Station, twenty years later. In: Proc 5th Int Conf Coastal and Port Engineering, Cape Town, vol 3, pp 2028–2042 Sasaki TO, Sakuramoto H (1984) Effect of rip current barrier on harbor shoaling. In: Proc 19th Coastal Engineering Conf, ASCE, pp 2091–2106 Stanley DJ (1989) Sediment transport on the coast and shelf between the Nile delta and Israeli margin as determined by heavy minerals. J Coastal Res 5:813–828 Strickland JD, Parsons TR (1975) A practical handbook of seawater analysis. Fish Res Board Can Bull Valderrama JC (1981) The simultaneous analysis of total nitrogen and total phosphorous in natural waters. Mar Chem 10:109–122

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