Indian Journal of Geo-Marine Sciences Vol. 43 (7), July 2014, pp. 1272-1280

Field measurements and numerical modeling of nearshore processes at an open coast port on the east coast of

P. Mishra1*, U. K. Pradhan1, U. S. Panda1, S. K. Patra2, M. V. RamanaMurthy2, B. Seth3 & P. K. Mohanty3 1ICMAM - Project Directorate, NIOT Campus, Pallikaranai, Chennai-600 100, India 2National Institute of Ocean Technology, Velachery-Tambaram Road, Pallikaranai, Chennai-600 100, India 3Department of Marine Sciences, Berhampur University, Berhampur 760 007 *[E-mail: [email protected]]

Received 19 August 2013; revised 30 October 2013

Port development and associated constructions such as groins, jetties, breakwaters along the shore front alter the coastal environment considerably. Gopalpur (19°18′13″ N : 84°57′ 52″ E), a seasonal port along east coast of India is under phases of development to an all weather open coast port and has a significant impact on the coast. Field data collected on beach morphology, waves, tides and currents at seasonal and annual basis for two years are analyzed. Numerical modeling of hydrodynamic, wave, sediment transport and shoreline evolution using DHI-Mike models are carried out. Present study describes the field data, the hydrodynamics, wave induced sediment transport and the nearshore circulation pattern suggesting an appropriate management plan.

[Keywords: Coastal processes, Modeling, Hydrodynamics, LITPACK, SLM Plan, Gopalpur]

Introduction development for converting it to a major open-coast Interactions among the coastal process parameters port. The construction activity along the shorefront (waves, tides, currents, etc), longshore sediment and has changed the shoreline significantly in the last two shoreline are very complicated and embrace abroad decades10,13,14. In the year, 2008, the Ministry of Earth spectrum of nearshore dynamics1-3. Port development Sciences, Government of India conceived a program and associated marine structures such as groins, to assess the impact of the port on the coastline. Field seawall, breakwaters, jetties interfere with littoral drift measurements on waves, tides, currents and beach and affect the coastline tremendously4-7; a plethora of geomorphology at spatio-temporal scales are papers has been written on shoreline process and made13,15. Numerical modeling of hydrodynamic, influence of marine structures purporting to stabilize wave and sediment transport using Mike 21 modules the shoreline have been distinctly unsuccessful in are carried out. The shoreline was simulated and coming to grips with the situation8. Examples along predicted using one dimensional LITPACK model. Indian coasts indicate that hard engineering solutions This paper describes the field data, the such as concrete protection measures designed to hydrodynamics, wave induced sediment transport and trap the sediment for building a protective beach, the circulation pattern suggesting an appropriate preventing erosion of beaches or sedimentation management plan. of inlet invariably fails and initiates various Materials and Methods irreversible situations by altering the coastal geomorphology e.g., accumulation of sediment, Study Area progression of coast on up-drift side whereas erosion Gopalpur Port (19°18'14"N and 84°57'52"E) 9-13 and recession of the shoreline on down-drift side . is located along the south , east coast of In such cases, field data and numerical modeling of India (Fig. 1). The coast is primarily depositional the nearshore environment is essential to understand in nature backed by parallel ridges of sand dunes the spatio-temporal variations for resolving coastal 1 (~ 10-12 m height), rich in rare earth minerals. zone problems . The coastline is oriented 48° E to true north. The Gopalpur, a seasonal minor port along the east wind and wave climate follow seasonal patterns coast of India is undergoing phases of infrastructural prevail in viz., southwest (SW)

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monsoon (June to September), northeast (NE) RCM 9 current meter at ~18 m depth and installation monsoon (October to December) and non monsoon or of tide gauge in the port for one year (June 2008- fair weather period (January to May). The climate is May 2009). Seasonal measurements of water levels semi-arid with an average rainfall of 1210 mm. and current extending over 3 weeks representing post Monsoon depressions formed over the Bay of Bengal monsoon (December' 08-January' 09), southwest during May to September contribute significantly to monsoon (May' 09) and northeast monsoon (November' the annual rainfal16; however, cyclonic storms during 09) were carried out at 8 and 18 m depths at Gopalpur northeast monsoon months often cross the coast and beach (GPL-8, GPL-18), Gopalpur Port (PORT-8, trigger temporary coastal erosion10. PORT-18), and Rushikulya (RUS-8, RUS-18) (Fig. Huge amount of littoral drift i.e., 1106 m3/yr 1). Monthly shoreline (berm position) mapping and moves along this coast17. Based on LEO data, a beach profiles are measured during May 2008 to northerly drift of 0.96106 m3/yr and 0.26106 m3/yr March 2011 for 30 kilometers of the coastline using of southerly is reported17; another study10, whereas, ArcPad DGPS and SR 1200 real-time kinematic 10estimated 1.1106 m3/yr and 0.51106 m3/yr GPS with position accuracy of ± 1 cm and ± elevation respectively. accuracy of 2 cm (Leica Geosystems, Switzerland). The port is under major renovation since 2007, the Bathymetry measurements were made using single port was constructed initially in 1987 by excavating beam ecosounder (ODAM Hydrotrac, USA) interfacing the backshore and connecting it through a 250 m wide DGPS to HYPACK 4.0 software. C-map and the channel. Two shore perpendicular groins of 530 m observed bathymetry was combined and interpolated long on south side and a 370 m north on both sides of for preparation of the final bathymetry map. The the channel are constructed during 2007 to 2010 to standard protocols are followed for setting up the instruments, measurements and data retrieval and maintain 250 m wide entrance channel from siltation. 13,15 A southern breakwater (2.6 km long) is under analysis . The absolutedata sets were utilized for construction since 2012 onwards at 2.3 km south of model set up, validation and analysis. south-groin as a part the proposed harbor. A series of Result and Discussion 10 groins are being constructed on the north of north- groin in an attempt to arrest the eroding north coast. Waves The Gopalpur tourist beach is located 6 km south and For a better clarity, the wave data were presented a major Olive ridley turtle rookery is formed north of under two broad seasons i.e., SW (May-September) Rushikulya estuary, 16 km north of the port (Fig. 1). and NE (October-April) monsoons.The Gopalpur Data coast is exposed to waves approaching predominantly Extensive field campaigns were carried out from from SSE, SE and S directions. Nearly 84% of waves May 2008 to March 2011 includes deployment of a reach the coast between 135-180° (southeast-south), Datawell directional wave rider buoy at ~22 m, a 14% waves from 180-225° (south-southwest) and the rest 2% are from 90-135° (east-southeast). Annually, the significant wave height (Hs) ranged from 0.26 to 3.29 m with an average of 1.06 m. During the SW monsoon, Hs ranged from 0.4 to 3.29 m with an average of 1.29 m; the NE monsoon values are from 0.26 to 2.18 m with a mean value of 0.71 m. The percentage distribution of significant wave height shows that nearly 37% of waves have heights of 0.5-1.0 m, 30% of waves have heights of 1.0 to 1.5 m and only 3% of waves exceed 2.0 m height. Seasonal distribution of wave indicates that during SW monsoon, 80% of waves are between 1.2 - 2.0 m and about 10% of waves are between 2.0 -3.0 m (Fig. 2a). During NE monsoon 92% of the waves are between 0.5 -1.0 m; whereas December, January and

Fig. 1. Map of the Study area showing data collection points. February months, nearly 94% of waves are between

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0.2-0.8m. Hs exceeding 2m was observed mostly and minimum water level variations of 1.32m during July and August consistent with high wind and and -1.08m were recorded on 2nd August, 2008 and cyclonic conditions in the Bay of Bengal. The 12th February 2009 respectively with respect to mean maximum wave height (Hmax) of 5.22m and 5.37m sea level (MSL). However, the maximum and was recorded during SW monsoon months (29th July minimum astronomical tidal component of 1.1 m and 11th August 2008). Hmax exceeded 4m during and - 0.99 m was observed on 15th October, 2008 September, November 2008 and May 2009 and 4th June 2008 respectively. in consistent with cyclonic storms events i.e., The main lunar semi-diurnal (M2) is most dominant No2 during 16-18 September 2008, KhaiMuk on constituents (53%) followed by the solar semi-diurnal 14 -16 November 2008 and Aila on 24-26 May 2009 constituent (S2) being the second dominant (26%). in Bay of Bengal. Tidal form number (F) was calculated to be 0.246 Peak wave period (Tp) ranged from 2.2 to (< 0.25) describing that the tide for the coast are semi- 28.5 seconds with an average of 11.2 seconds. Peak diurnal (Table 2). period with more than 12 seconds occurs nearly 42%; Tidal range is mostly within 2m for Gopalpur 21% is shared by 10-12 seconds and about 37% is less coast and classified as micro-tidal or lowermeso-tidal 21, 22 than 10 seconds. During SW monsoon, Tp ranged shore . A surge level (+41 cm) was recorded on between 5-20 seconds, confined to two different wave the 2nd of August 2008 coinciding with the day following groups one is 7-10 seconds contributing 50% full moon day and in between two low pressure systems 15 and 22% falls between 14-17 seconds and in that caused severe erosion all along Odisha coast .

NE monsoon, 81% of data occurs in the range of Currents and Circulation 9-15 seconds (Fig. 2b). The measured current speed and direction were Nevertheless, on basis of significant wave height resolved into alongshore () and cross-shore () range and averages, the wave data can be categorized currents. Mean vector directions of coastal current as "very low energy" for post monsoon (DJF), "low vary seasonally. Mean current speed is maximum energy" for Northeast monsoon (ON), "moderate (~24 cm/sec) during February 2009 and minimum energy" for transition or pre monsoon (MAM) and mean current speed (~12 cm/ sec) was recorded in "high energy" conditions for southwest monsoon July, 2008. The current was towards NE or ENE (JJAS) period (Table 1). during January to June, while in July, the current Tide changes its direction to ESE and from August to Tides and tidal currents in the ocean basin are December maintained towards SSW or SW. The essentially produced by the gravitational forces mean vector and steadiness of current is highest in exerted on ocean by the sun and the moon18,19. March 2009 whereas the lowest mean vector speed The observed sea surface elevations were analyzed and steadiness is observed in July 2008. The angle of for tidal harmonic analysis using MIKE21 tool Table 1—Significant Wave Height (Hs) in meters with using the Rayleigh Criterion20. The maximum Periods Min Max Average Classification SW (JJAS) 0.70 3.29 1.49 High NE (ON) 0.40 2.18 0.88 Low Post (DJF) 0.26 1.83 0.53 Very low Pre (MAM) 0.35 2.19 1.09 Moderate Annual 0.26 3.29 1.06

Table 2—Major tidal constituents computed for June 2008 to May 2009 tide data. Constituents Speed = 360/T Amplitude (m) Phase (o) M2 29.0 0.53 226 S2 30.0 0.2 262 K1 15.0 0.13 274 O1 13.9 0.05 316 Fig. 2—Percentage of occurrence of a) Significant wave height N2 28.4 0.11 214 (Hs) in meters and b) Peak period (TP) in seconds during SW and NE monsoons. MSF 1.0 0.03 130

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maximum variance is found in the month of Sand volume calculated from profile data indicate December. During the months of August, November highest volume of sand accreted at 0.5 km south of and December the cross shore and alongshore groin whereas maximum erosion occurred at 1 km on components are westward and southward whereas in the north of north-groin; volume of sand accumulated all other months it is mostly towards northerly except is 0.66106 m3 on the southern side of the port and a transition during July. 0.42106 m3of sand lost by the end of our observation

Shoreline and Geomorphology (Fig. 4). Considering the sediment budget on both 6 3 During our study, the channel groins were extended sides, an amount of 0.2410 m of sand is excess and phase wise to different lengths and with that, the trapped due to extension of southern shoreline position invariably varied (Fig. 3). groin which has resulted in evolving a wider beach of Temporal variation of shoreline indicates that the 100-250 m width on south. beach has consistently gained sediments on the south The beach attains minimum level and retreat and eroded on the north of the port. landward during SW monsoon month (August). On an average, 100-250 m wider beach was formed Beach profiles at other transect follow seasonal cycle on the south and 80-100 m width of beach was lost on of erosion/deposition processes. Continuous erosion the north side of the port (Table 3); the major on the north side of the port has threatened two gain/loss of sand is mostly limited to 1.5 km on the fishing villages i.e., Bada Aryapalli and Sana south and 2 km north of the groins and beyond that Aryapalli settled on backshore dunes. The erosion at beaches are comparatively stable. However, recently Gopalpur tourist beaches are cyclic and seasonal; the constructed structures i.e., series of groins on the north shoreline changes at Rushikulya turtle rookery is side to protect the coast has amplified the erosion rate largely due to natural causes i.e., northward growth of (Fig. 3 shoreline data for May'13, Fig. 9a). the sand spit indicating the coast is not influenced by the port activities so far23.

Model description

Hydrodynamic Hydrodynamic (HD) flow module of Mike 21 provides the hydrodynamic basis for other modules. The model domain (28km×8km) is set-up with a grid resolution of 100m×100m with 3 boundaries integrating bathymetry data. Simulation of the water level variations and flows in response to a variety of forcing functions are resolved on a finite difference scheme. Water level data observed at 8m depths on the north (RUS-8) and south (GPL-8) boundaries and the open ocean side with no flux are inputs for the

Fig. 3—Temporal variation of shoreline positions near port.

Table 3—Temporal variation of beach width (m) gain (+) or loss (-) with respect to June 2008 at 0.5km intervals on both sides of the port. South of Port North of Port Months 0 km 0.5 1.0 1.5 0 km 0.5 1.0 1.5 2.0 Aug'08 120 53 14 13 -28 -49 -40 -14 8 Aug'09 176 113 59 16 -34 -79 -60 -34 -17 July'10 195 145 97 28 -34 -97 -76 -42 -25 Dec'10 220 163 116 41 -52 -97 -76 -50 -30

Mar'11 230 190 130 -20 -50 -90 -80 -50 -30 Fig. 4—Volume (×106 m3) of sand gained and lost on both sides May'13 260 200 160 80 -40 -100 -90 -80 -80 of the existing channel and pier

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model simulated for 15 days with a time step of is given as lateral boundary condition. Minimax 30 seconds. The model output is validated with model criteria with ± 60o is used for minimization of the observed water level collected at Port. the maximum error in the parabolic approximation for Several combinations of the calibration parameters a given aperture width. For bottom dissipation, are verified. Eddy viscosity calculated by means Nikuradse roughness parameter (kN) is specified as a

of the Smagorinsky formula with a constant (= 0.5), constant (0.002) and Y12 =1,Y = 0.8 and =1 are the bottom friction specified by Chezy number calibrated wave breaking parameters. 1/3 (C = 40 m /s) and wind friction parameters with The buoy observed wave data for three different fw = 0.0016 for < 8 m/s and fw = 0.0026 for > 10 m/s seasons were extracted and simulated. The simulated are used in the model. wave height is compared with the directional wave & Calibration is made through several set up to tide gauge wave height (Fig. 6). Pearson's correlation optimize the best agreement between result and coefficient (r=0.78 to 0.79) for all three seasons simulation was repeated for all three seasonal indicates that the model is well calibrated. observations. Comparison between the measured Sediment Transport (solid line) and simulated (dotted line) water levels for SW monsoon (May 2009) is shown in Fig. 5a. Sediment Transport (ST) model simulate currents Good agreement and Pearson's correlation (r=0.96 to and waves from HD and PMS model as inputs to 0.99) are observed for all the three seasons. The estimate the sediment transport rates and bed level current data collected off port (PORT-18) in the changes of non-cohesive sediment. Two setup criteria model domain is used for validation. The simulated consisting, the spatial variation of the geometrical and measured U and V velocity components are properties of the bed material and a sediment shown in Fig. 5b & c. A good correlation for transport rates calculated using STP for possible U-component (r ~ 0.72 to 0.96) and for V-component combinations of relevant parameters such as (r~0.74 -0.95) was obtained in tidal current validation parameters for tolerance in calculation of concentration for all the three seasonal observations. is 0.0001, maximum number of wave periods is 100s, relative density of sediment is 2.65, critical value of Wave shields parameters is 0.05 and reference water Parabolic mild slope (PMS) model makes a temperature is taken as 20° C considered. parabolic approximation to the elliptic mild slope The bed level changes (dz/dt) in m/day are in the equation considers refraction, diffraction and shoaling order of 0.001 m/day, larger changes occur during due to varying depths (DHI, 2007). Higher resolution May 2009. It should be noted that the erosion and bathymetry (10m×10m) with 180° rotation is used for deposition rates predicted by the model refer to initial model domain set up with quasi-stationary bed level changes, which are indicative of probable 24 description. Observed wave height (Hrms), peak wave zones of erosion/deposition . During post monsoon, period (TP) and mean wave direction (MWD) is used bed level changes are positive in the whole domain; for offshore boundary, while symmetrical wave input during SW monsoon (May 2009) bed level changes

Fig. 5—Validation of a) water level, b) U component and Fig. 6—Comparison of observed and simulated wave height for c) V component between measurements and simulated values. a) post, b) SW, c) NE monsoons.

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are positive on the southern side of the port and in parameters. Three major result parameters viz., coastal the channel indicating active zones of deposition current, wave height and sediment transport rate are (Fig. 7a). Bed level changes are negative on the both summarized in Table 5. sides of the port during NE, and on the north side of On an average the nearshore currents on the north the port in SW months indicating erosion. The above are swifter than south side of the port. A maximum trends are corroborated with field data. Sediment (1.01 m/s) northerly current was observed across the distribution pattern indicates that maximum sediment profile-5 at a distance of 18 m from the coast in movement occurs in SW (May 2009) with strong Pre-monsoon season, whereas a minimum (0.2 m/s) eddy circulation leading to active sediment transport northerly current was observed across the profile-4 at while, it is less during NE (November 2009) (Fig. 7b). a distance of 30 m from the coast in NE-monsoon. Throughout the year, the current is northerly and LITPACK maximum across the profle-5 and nearest to the coast LITPACK is a one-dimensional model simulates as compared to other profiles. Coastal currents are littoral sediment transport (LITDRIFT) of non stronger and spreading over a wider surf zone in the cohesive sediments and shoreline evaluation SW monsoon due to the high wave action (Table 5). (LITLINE) (DHI, 2007). The LITDRIFT profiles are The magnitude of the surf zone currents follow the created using bathymetry, roughness, mean grain size, order of SW > Pre > Post > NE-monsoon. fall velocity and geometrical spreading. The roughness Comparatively, current at profile-4 is feeble and fall velocity constant values are 0.004 m and because it falls under wave shadow zone, immediate 0.022 m/s and the average mean grain size and north of northern groin. This is because the wave geometrical spreading are 0.26 mm and 1.5, mean of approach from SE-S, which makes an angel of 100 offshore sediment samples. 22 - 45 to the groins, resulting minimal coastal The LITDRIFT simulation was carried out for current and sediment transport at Profile-4, whereas different seasons for 3 cross-shore profiles (0.2 km, 1 maximum coastal currents was seen at Profile-2 and km and 2 km away from the groins) on both sides of Profile-5 (Table 5). the port. Profile 1, 2, 3 are on the south and profile From the bathymetry cross-section, the beach slope 4, 5, 6 are on the north side of the port. The nearshore at profiles-2 and 3 are gentle, thus allowing the waves phenomenon is simulated assigning average wave to break at a higher distance from the coast. parameters (Table 4), profile details and sediment Generally, the higher waves break in SW monsoon at a higher distance and smaller waves break near the coast in NE-monsoon. However, the surf zone bathymetry is very steeper near the profiles-4 and 5 allowing the waves to break nearer to the coast throughout the year. The breaking wave heights are lesser near the profile-4 in the shadow zone of the groin. It is observed that the wave approaching at higher angles with the groins triggering swifter surf zone current and thus higher sediment transport rate. The transport rate follows the trend of surf zone current (Table 5).

The LITLINE simulates the coastline using wave climate and six beach variables i.e., beach position, Fig. 7—(a) Bed level changes dz/ dt (m/day) and (b) Average sand dune position, and height of dune, number of sediment transport rate m3/yr/m during May 2009. cross sectional profiles, offshore depth counter and Table 4—Average wave parameters used in LITDRIFT module. active water depth. A hypothetical baseline was fixed at 138° in the extreme backshore with respect to Season Hrms (m) Tz (sec) MWD (deg) coastline orientation incorporating the coastal Pre-monsoon (MAM) 0.96 5 169 structure positions on both sides of the port. The base SW Monsoon (JJAS) 1.32 6 166 or reference line with a segment of 50 m interval was Post-Monsoon (ON) 0.78 7 157 prepared and June 2012 shoreline was overlaid in an NE- Monsoon (DJF) 0.47 5 159

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Table 5—Nearshore parameters from LITDRIFT simulation. Profile Maximum Current (m/s) Breaking Wave height (m) Sediment transport rate (m3/s) Pre-Mon Mon Post-Mon NE-Mon Pre-Mon Mon Post-Mon NE-Mon Pre-Mon Mon Post-Mon NE-Mon P-1 0.50 (62) 0.61 (102) 0.32 (60) 0.21 (38) 0.77 (66) 1.27 (180) 0.89 (90) 0.47 (60) 0.017 0.040 0.008 0.001 P-2 0.54 (90) 0.66 (132) 0.34 (90) 0.23 (48) 0.85 (120) 1.30 (216) 0.90 (132) 0.47 (64) 0.019 0.044 0.010 0.002 P-3 0.52 (102) 0.64 (150) 0.22 (32) 0.23 (54) 0.86 (132) 1.32 (220) 0.76 (138) 0.47 (66) 0.019 0.044 0.007 0.002 P-4 0.41 (22) 0.39 (20) 0.34 (84) 0.21 (30) 0.67 (6) 0.75 (12) 0.68 (12) 0.49 (12) 0.009 0.028 0.005 0.001 P-5 1.01 (18) 0.98 (18) 0.56 (30) 0.37 (22) 0.76 (18) 0.87 (24) 0.80 (24) 0.46 (12) 0.036 0.059 0.011 0.001 P-6 0.61 (78) 0.74 (114) 0.39 (78) 0.26 (42) 0.86 (102) 1.30 (182) 0.88 (114) 0.47 (24) 0.022 0.053 0.010 0.002

*values in parentheses are distance from the coast in meter

ArcGIS environment and the origin cross-section was 70 m, however, simulation with a beach considered as first profile. The offshore depth contour nourishment of 0.036 m3/sec (3111 m3/day) per km was fixed at 20 m and active depth at 8 m. The wave length of the coast stabilizes the beach effectively climate was prepared for 15 parameters (DHI, 2007) (Fig. 10a, b). from the observed wave data. The spectral dissipation and spreading constants were specified with 2 and 0.5 respectively.

The simulation was carried out for evolution of the 2.5 km coastline (active zone) on both sides of the port to predict the scenario of the coastline for 5 years (2012-2017). The coastal structures such as groins and breakwaters were incorporated in the model along with bathymetry cross shore profiles (Fig. 8). The predicted coastline shows that immediate to north of northern groin is eroding (Fig. 9a, 10a) and the port channel is silting up (Fig. 9b, 10b). On the southern side of the south groin remains stable, however due to presence of the breakwater, erosion on the tip of the beaches and by passing of the sediment is trapped in the port channel (Fig. 9b). Simulation with the structures alone indicate that 750 m coast in between first two north groins erode incessantly to the order of ~15 m /year and by the end of 2017, the coastline retreat about

Fig. 9—Photographs showing (a) upper panel: erosion of north side; (b) lower panel: sedimentation in the Port channel (May Fig. 8—LITLINE model set up with the existing structures 2013) (courtesy: B. Behera)

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the sediment along the coast. The beach profile data on the north of the structures indicates that during NE monsoon months active cross-shore (onshore-offshore) sediment transport play a key role in seasonal berm development and recycling the sediment between beach and nearshore. As the predominant wave incidence angle is mostly in between 20-25 of shore normal from SSE and the northerly transport ensues throughout the year, periodic beach fill/beach nourishment between the shore protecting groins can be contemplated as an additional option for the management of northern eroding coast. In case of Gopalpur coast, the beach at 1.0 km

north is mostly affected with extension of southern Fig. 10—Shoreline change prediction scenario for 5 years (2012- groin. During 1987, in the beginning days of the port, 2017) with the infrastructures at Gopalpur port (A) without sand the channel is used to be dredged by hydraulic pump nourishment and (B) with sand nourishment and sand used to be bypassed through pipes to the Conclusions northern side of the port and later this sand is carried Gopalpur, located along east coast India is historically by natural waves, currents and redistributed within depositional and stable environment primarily controlled adjoining coast facilitating formation of fully grown by unidirectional northerly alongshore sediment berms, wider beach of 250 m wide26. This was found transport of the order of 1.1 to 1.3  106 m3/year23. By to be practically feasible methods in stabilizing the the end of our study (March 2011), due to beaches north of structures (piers), however, due to construction of groins, a total volume of 0.66106 m3 high operational cost, the practice was abandoned; of sand has been accumulated on the southern side with the progression of the groins and non supply of whereas 0.43106 m3 of sand has been lost on northern sand the scenario has completely changed. Thus, to side of the port (groins). About 300 m width of the start with, we recommend a shore face nourishment north beach has been eroded and sand dune of 12 ~ 15 m 3111 m3/day within 1 km (between the groins) on the high has been battered and the shoreline is retreating north of Gopalpur Port would be indispensable to at a rate of ~ 15-20 m/year landward with respect protect the beaches immediately from further erosion. to 1987-1988. To manage the erosion, a series of The protection schemes can be further extended after shore perpendicular groins of different lengths evaluation and nourishing the shore face with supplemented with shore parallel geo-tubes within sediment available from capital dredging. 3km north is proposed as a part of engineering As a number of civil structures are going to take solution and is under operational. As discussed, the place in near future, therefore, it is highly essential to study infers the cause of erosion as disparate for this monitor the coastline regularly keeping the present coast, however, erosion is continuous, permanent, and information as a baseline. Based on the sediment initiated by structures (manmade) mainly and partially budget variations, the planning of shore face natural and/or seasonal, thus, the engineering solution nourishment needs to be synchronized and a realistic alone may not be only viable option for the value can be rationalized for proper management management of the coast. of these beaches as they support one of the Worldwide, beach nourishment is considered as world's largest olive ridley rookery habitats and a 'natural' or 'soft' solution of combating coastal depository of some of the economically important rare erosion as it artificially replaces the deficit in earth minerals. the sediment budget over a certain stretch with a corresponding volume of sand25. Our study Acknowledgements exhibits that the anticlockwise eddy circulation on the Authors are grateful to Dr S. Nayak, secretary, north of the structures keep sediment afloat in high Ministry of Earth Sciences, Govt of India for his wave conditions (SW monsoon) whereas in low guidance, encouragement and providing necessary wave conditions, shore parallel transport redistributes funding.

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