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This work presents a review of hydrological data known as water levels and volume flows that have been recorded and then processed to render a contour about the hydrological situation of the Danube River near Tulcea. On-site measurements have generated daily data on river flows and levels over a 3-year period (2003, 2004, 2006), their interpretation being important for knowing the water drainage regime. Moreover, the characteristic values can have a practical interest in some river design works, such as hydrotechnical flood defense constructions that may occur as a result of elevated levels above a certain threshold or may be beneficial during works or exploitation of river bed resources. In order to accurately present the importance of knowing the river level variation, it is necessary to process, verify and interpret all data on the levels and flows, establish links and graphical correlations, and determine the characteristic values over the multiannual period. The results obtained from the measurements are described in the four periods of the year, and the conclusion shows that each period is manifested both in climatic and hydrological terms by specific characteristics and phenomena.
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ISSN (Print): 1844-6116
ISSN (Online): 1884-6116
Journal of Marine technology and Environment Year 2018, Vol.1
Alexandru Banescu1, Lucian Puiu Georgescu 1, Catalina Iticescu 1 & Eugen Rusu 1
1 Dunarea de Jos” University of Galati, 47, Domneasca Street, 800008, Galati, Romania, e-mail address:;;;
Abstract: This work presents a review of hydrological data known as water levels and volume flows that have been
recorded and then processed to render a contour about the hydrological situation of the Danube River near Tulcea. On-
site measurements have generated daily data on river flows and levels over a 3-year period (2003, 2004, 2006), their
interpretation being important for knowing the water drainage regime. Moreover, the characteristic values can have a
practical interest in some river design works, such as hydrotechnical flood defense constructions that may occur as a
result of elevated levels above a certain threshold or may be beneficial during works or exploitation of river bed
resources. In order to accurately present the importance of knowing the river level variation, it is necessary to process,
verify and interpret all data on the levels and flows, establish links and graphical correlations, and determine the
characteristic values over the multiannual period. The results obtained from the measurements are described in the four
periods of the year, and the conclusion shows that each period is manifested both in climatic and hydrological terms by
specific characteristics and phenomena.
Key words: Danube River, Tulcea, water level, volume flow, measurements
The Danube River is the second river in Europe,
crosses 2840 km from the Black Forest, the
Donaueschingen in Germany, to the Black Sea. The
Danube has build up one of the most interesting and
beautiful deltas in Europe and even in the world. The
arms of the Danube are the major arteries by which the
river provides the deltaic space, the solid and liquid
flow. The deltaic space is directly influenced by the level
and the amount of flow that the river carries in different
proportions depending on the period [1], [2].
The hydrographic network of the Danube Delta is
extremely complex, showing a particular geographic,
economic, and tourist interest. It provides water supply
to lakes as well as airworthiness. This hydrographic
network comprises the Danube arms (Chilia arm, Tulcea
arm, Sulina arm, Sfantu Gheorghe arm), lakes, ponds,
marshes, channels, and sheds [3].
At present, the activities of valorizing the Danube's
natural resources, the tourism and trade have increased
the transport on water, requiring the balanced
development of both the waterways and the types of
ships, correlated with the conditions of protection the
natural environment of the river, which requires
knowledge of the Danube's drainage regime [4].
Very important issues in order to ensure a proper
circulation of the water on the Danube are not the very
large flows of the river, produced over a short interval in
spring, but, in particular, the existence of a long period
of time with relatively high flows. In this case, given the
correspondence between flows and levels, an active
circulation of the water can be ensured in the inner
depression areas, facilitating the evacuation of the
wastewater loaded with noxious waste at the end of the
summer [5], [6].
The drainage regime of the river is depending on
variation in time over a month, a season, a year or more
of the amount of water flowing within a river section.
The liquid leak can come from rains, snow and even
from groundwater. The study of the regime is given by
the knowledge of the variation in leakage and sources of
supply. The variation of the river supply sources over a
year requires a similar variation in the flow of the river
water, uniformed in a sequence of characteristic periods,
referred as drainage phases. The frequency and often the
duration and the dimensions of the phases show the
variation in time of the supply sources, which in turn are
ISSN (Print): 1844-6116
ISSN (Online): 1884-6116
Journal of Marine technology and Environment Year 2018, Vol.1
strictly dependent on the interference of the climatic
factors in the climatic seasons [7].
Regarding the influence of the physical geography
factors on the rivers, the processes and the hydrological
phenomena within the river basins are determined by the
position of our country, the height and orientation of the
relief and, to a greater extent, the physical geography
factors in the basin. In the processes of the leakage
formation and evolution, the main role is played by the
climate, which, due to the precipitation, temperatures,
wind, evapotranspiration and frost regime, inflates
decisively the water reserves as well as the leakage
regime [8].
An important problem is the flooding of deltaic
space, as a complex hydrological process. This is very
important in the dynamics of the evolution of all
components of the natural system. Strongly dependent
on the Danube water regime, the degree of flooding
supports both surface alluvial processes at elevated,
linear levels at low levels, as well as the water supply of
indoor lake depressions. Also, related to the process of
flooding, the deltaic territory imposes restrictions on the
location, sizing, and realization of various constructions,
habitable surfaces, etc. [9]
The main premises that condition the flooding
process are its hypsometric peculiarities, the amplitude,
and periodicity of the Danube's maximum levels, to this
being added, at present the restriction of flooded areas,
having as a result the covering of some areas [10].
Both for the Danube Delta and for the Danube
localities, there is a risk of failure, where it may occur
the phenomenon of settlement the dam, or if not, there is
a major danger of producing an infiltration because of
the duration of the very long flood. Also, there is a
permanent risk of erosion sometimes accompanied by
landslides which endanger housing and households. At
the same time, there is a permanent risk of erosion
sometimes accompanied by slopes of ground that
endanger habitats or households [11].
In this context, the present work describes the
situation of levels and flows in different forms of
analysis for a 3-year period, how these data were
collected and the methods of analysis used.
The target area is located on the Danube at Km
71 near the city of Tulcea. The location of the
hydrometric station is shown in Figure 1.
The recording of the results of the water levels
in the Danube River was determined by direct reading a
hydrometer placed on the river, using a recorder called
the limnometric device. It has the role of knowing the
evolution over time, by discrete (discontinue) values of
water levels and of checking and correcting the recorded
levels [12].
Figure 1 Map with the location of the hydrometer
station at Km 71 on the Danube
The level measurement programs (hydrometric
reading) are set by the hydrological station staff
according to the flow regime (small, medium, or high
water). When there is a constant treatment regime, the
recordings of the level and the flow of the river are made
at the standard observation hours (8 and 20).
The recorded water levels are used directly to
indicate the imminence of production floods and
indirectly to specify the hydrograph of the water flow
using the limnometric key [13].
As regards the water levels, given the short time
they have been observed or recorded, they are
considered as instantaneous values. Level records are
expressed in meters, relative to ''0 graduated tool''. The
share ''0 graduated tool'' is expressed in mrMN (Black
Sea landmark).
The level values are important, both as values in
themselves, notably by specifying flood areas and the
moment when the flood is produced, as well as indirectly
by determining with the help of the limnometric key the
hydrographic water flow and the hydrographs useful for
hydrological forecasting and monitoring of basin water
The evolution of water flow hydrographs over time
is helpful for all activities of knowledge of the evolution
of the river flow regime over time (hydrological forecast,
hydrological parameters, integrated water resource
The determination of the water flow hydrographs is
achieved by: direct measurements with specific
equipment or with the help of determinations (discreet
values) of water flows and/or slopes and sections. On the
basis of these and the levels existing at the time of the
water flow determination, it is specified a correlation
"flow-level" - limnometric key.
ISSN (Print): 1844-6116
ISSN (Online): 1884-6116
Journal of Marine technology and Environment Year 2018, Vol.1
With the help of this, and the help of level
hydrographs, the water flow hydrographs are then
determined [14].
The frequency of the water flow measurements
shall be determined by the personnel of the hydrological
stations, mainly in the phase of the regime, by the
requirements marking the limnometric keys. The basic
condition is to specify at any time the value of
instantaneous and average hourly / daily water flows
with an error below 15%.
The determination of the water flow is done by
measuring the speed rate of the water and the wetted
section. The water flow results from the multiplication of
the watered section at the average speed. Speed is the
most difficult variable given by the determinant due to
the fact that it varies with width and depth in the profile
The usual hydrometric technique for measuring the
water flow consists in launching into a watercourse, in
the direction of the water flow a propeller in order to
determine the water velocity at different points located
on several vertical sections of the watered section. The
method of calculating the flow is called '' speed section ''.
The evolution of water flow rates over the course of the
river is determined by means of level records and
limnometric keys, "water flow-level" curves. The
"speed-section" method, as mentioned above, is based on
the determination of water depths at various points of the
wet section and its velocity at different vertical points
located within the perimeter of the wet section.
The method of determining the average velocity in
one vertical is called the "five-point" method, which,
depending on the depth of water in the bed, is reduced to
the one-three-point method.
For measuring the water flow the hydrometric
propeller has been used. The hydrometric propeller is a
device designed to measure the water current for the
calculation of water flows.
The operating principle of the hydrometric propeller
is based on counting the rotations that make them in a
unit of time a propeller under the influence of the water
In the present work there are presented
developments in water levels and flows of the Danube
River at the Tulcea arm for the years: 2003, 2004 and
2006. In those years, there were correlated daily data of
water flows and levels in Tulcea harbor, the level records
are expressed in meters, relative to ''0 graduated tool''.
The share ''0 graduated tool'' is expressed in mr MN
(Black Sea landmark). Fig. 2 [subplots (a), (b), (c), (d),
(f), (g), (h)], and the flows being expressed in m3/s Fig.
2 [subplots (a), (b), (c), (d), (e), (i), (j), (k)].
The results are presented in the first phase in the
form of tables and in the second phase as figures.
Figures are graphs showing the levels and the water
flows of Danube near Tulcea for the years: 2003, 2004,
2006, in different forms of representation. Tables contain
the volume water flows and levels for the four periods of
the year: winter, spring, summer, and autumn periods.
Table 1. Sets of minimum and maximum levels
distributed over the four periods of the year
ll [m]
ll [m]
ll [m]
ll [m]
ll [m]
ll [m]
Table 2. Sets of minimum and maximum volume water
flow distributed over the four periods of the year
ISSN (Print): 1844-6116
ISSN (Online): 1884-6116
Journal of Marine technology and Environment Year 2018, Vol.1
ISSN (Print): 1844-6116
ISSN (Online): 1884-6116
Journal of Marine technology and Environment Year 2018, Vol.1
Figure 2 Graphics describing the situation of water
levels and the volume flows with data collected during
2003, 2004, 2006
The analysis made showed that the maximum
level and flow was recorded in 2006 and the lowest level
and flow in 2003. The level and maximum flow in 2003
were registered by the middle of January, continuing
with decreases and rises in values all over the year
during the year, thus setting in September the lowest
level and flow, comparing with the rest of the analysed
years - Fig. 2 (a), Fig. 2 (d), Fig. 2 (e), Fig. 2 (f), Fig. 2
(i). The 2003 situation is similar to the one of 2004 and
2006, only in terms of the minimum level / flow. The
minimum level / flow for the three years considered in
the analysis have been recorded during the autumn - Fig.
ISSN (Print): 1844-6116
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Journal of Marine technology and Environment Year 2018, Vol.1
2 (a), Fig. 2 (b), Fig. 2 (c), Fig. 2 (d), Fig. 2 (e), Fig. 2
(f), Fig. 2 (g), Fig. 2 (h), Fig. 2 (i), Fig. 2 (j), Fig. 2 (k).
The autumn periods can also record extremely
different situations from one year to another, as in other
years not too many can trigger a rainy episode that can
generate large autumn waters. The occurrence of such a
massive leakage episode is also facilitated by the sharp
decrease of the air and soil thermal regime. In the above-
mentioned case, it was shown that at the end of the
summer period and the beginning of the autumn period
the precipitations were missing in the territory resulting
in low levels / flows.
The year 2006 is similar to 2004 in terms of the
maximum level / flow recorded during the spring period
- Fig. 2 (c), Fig. 2 (d), Fig. 2 (e), Fig. 2 (g), Fig. 2 (h),
Fig. 2 (i), Fig. 2 (k).
The spring season coincides with the season
where the average daily air temperature is between 00C
100C, favoring the melting of snow reserves in the
territory. In this period, the river's levels and flows are
increasing, sometimes faster, sometimes slower,
depending on the rate of the snow melting, and the
possible overlapping of rains over the snow.
It should be noted that the maximum annual
drainage of the water can take two forms, namely: high
water and floods.
In general, the two notions characterize the
same phase of the regim, but they have quite a different
As far as floods are concerned, it is a very
characteristic hydrological phenomenon for all rivers,
being fed by surface sources (rain, snow melting).
Analyzing the three years, we can conclude that the year
2006 shows a significant flood with values exceeding
7000 m3/s - Fig. 2 (c), Fig. 2 (e), Fig. 2 (k). A similar
situation was recorded in 2004, but with much lower
values compared to 2006, with quantitative values
slightly above 5000 m3/s - Fig. 2 (b), Fig. 2 (c), Fig. 2
(e). Despite the large differences in values for the 2
years, their likeness is given by the flood period.
Floods can be defined as sudden and strong
increases in the river level / flow due to the torrential
rains, long-lasting rains, or accelerated snow melting.
The year 2003 recorded in January the highest level
/ debit for that year. A less normal situation, comparing
with the rest of the years, because in the winter period,
the overlapping season in which the average daily air
temperature is below 00C, precipitation is in solid form
(snow) and the river has a generally low drain. On the
river, frost formation of different kinds, of some
intensity and duration, occurs during this period. In most
of the territory, there is a minimum drainage period,
called hydrology, the period of the small winter waters.
Various different climatic and hydrological
situations can be recorded in the summer period, in
spring floods can continue, an example being the first
part of the summer of 2006 - Fig. 2 (c), Fig. 2 (d), Fig. 2
(e), Fig. 2 (h), Fig. 2 (k). Generally, during this period,
there are periods of small summer waters, where the
Danube gradually passes from surface feeding (rain) to
pure underground feeding. At this stage, the river has a
general trend of decreasing flows, from the maximum
value to the minimum value, which in most cases occurs
in September.
In the figures: [Fig. 2 (l), Fig. 2 (m), Fig. 2 (n)], the
normalized values corresponding to the minimum
(down) and maximum (up) levels are presented,
providing a more detailed picture of these data.
Knowing the minimum and maximum levels /
flows, is also relevant in designing, exploiting hydro-
technical constructions and complex water management.
Knowing the duration of the levels / flows is also
important for many practical activities, as: the placement
of machines, hydro-aggregates and machines in the
minor bed during the execution of works or the
exploitation of resources from the bed (ballast, sand,
water supply, etc.) in flood and ice protection, etc.
The analysis made in this work lead to the
conclusion that during one year four characteristic
periods occur in the hydrological regime of the river.
These are: the winter period, the spring period, the
summer period and the autumn period. Each period is
manifested both in climatic and hydrological terms by
specific features and phenomena.
Large waters occur most often in the spring, at the
slow and prolonged melting snow. Their duration and
intensity depending on the physical-geographic
conditions that generate the leakage, namely the
reservoir of the water in the basin, the rapidity of the
melting of the spring snow, the overlapping or not with
the beginning of the spring rains.
Having a detailed and comprehensive picture
regarding the Danube flows and levels is important
because knowing these values can be of a practical
interest for the river development works, such as the
protection of the dikes' height (avoidance of a major
flood risk).
As a general conclusion, the scientific and practical
importance of knowing the fluctuation of the river levels
/ flows, it can be highlighted by several important
aspects, such as the knowledge of level variations during
the year or in a multiannual profile, allows for a general
understanding of the determinant role of the physical-
geographic factors on the formation and the
characteristics of the leakage through the bed.
To playback as eloquent as possible the importance
of knowledge of the level fluctuations of a river, it is
necessary to process, verify and interpret all data on the
levels / flows, establish links and graphical correlations,
ISSN (Print): 1844-6116
ISSN (Online): 1884-6116
Journal of Marine technology and Environment Year 2018, Vol.1
and determine the characteristic values over the
multiannual period.
This work was carried out in the framework of the
project proposal ACCWA (Assessment of the Climate
Change effects on the WAve conditions in the Black
Sea), supported by the Romanian Executive Agency for
Higher Education, Research, Development and
Innovation Funding - UEFISCDI, grant number PN-III-
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... The lower course of the Danube runs at a distance of 1,075 km between Bazias and Sulina, making a border with Serbia 235, 5 km, Bulgaria 469, 5 km, Republic of Moldova 0, 6 km and Ukraine 53, 9 km. Because the Danube crosses a multitude of natural regions, the lower course is divided into 5 sectors, as follows: Carpathian Defile 144 km, South-Pontic Sector 566 km, Pontic Oriental Pond Sector 195 km, Predobrogean Sector 80 km and the Deltaic Sector 90 km (Banescu et al., 2018). The Danube River collects most rivers in Romania except those in Dobrogea, which flow into the Black Sea. ...
... Further studies give different values for multiannual average flows. Thus, Table 1 and Table 2 show the multi-year average/maximum flow rates for different ranges (Banescu et al., 2018). Generally, in the course of one year, the minimum drain on the Danube is recorded at the beginning of spring, on classes of debit values and the lowest flow rates occur in the winters with very low temperatures, when influenced by the evolution of ice formations. ...
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The mouths of the Danube River in the Black Sea represent the main southern entrance in the seventh Pan European transportation corridor that links the Black and the Northern seas and is the most important inland navigable waterway in Europe. For this reason the coastal area close to the Danube Delta is subjected to high navigation traffic, which is crucially affected by the strong processes mainly induced by the interactions between the waves and the currents generated by the Danube River outflow. From this perspective, the objective of the present work is to develop a computational framework based on numerical models able to evaluate properly the effects of these interactions and to provide reliable predictions concerning the wave and current conditions corresponding to various environmental patterns. Following this target, a wave modelling system, SWAN based, was implemented in the entire basin of the Black Sea and focused on the coastal sector at the entrance of the Danube Delta. As a next step of the modelling process, SWAN simulations were performed at two different computational levels, considering in parallel the situations without and with the current fields for the main environmental conditions characteristic to the target area. The first level covers the entire coastal area at the mouths of the Danube River and has a resolution in the geographical space of 500m. The second is a computational domain with the resolution of 50m that is focused on the Sulina channel, which is the main navigation gate at the mouths of the Danube River. The results show that the presence of the currents induces relevant enhancements in terms of significant wave heights. Additionally, the Benjamin Feir index (BFI) was also evaluated. This is a spectral shape parameter that is related to the kurtosis of the distribution and indicates the risk of the freak wave occurrence. The enhanced values for BFI in the case when the current fields are considered in the modelling process indicate also an elevated risk from this point of view. In situ measurements have been also performed in the target area and they confirm in general the results of the numerical simulations. The work is still ongoing and, as a further step, data assimilation techniques are considered for improving the wave predictions at the mouths of the Danube.
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The present paper mainly aims at assessing the Danube water quality as regards its physicochemical parameters, as well as at monitoring the effect of the wastewater treatment plant activation in the city of Galati in 2012. The Principal Component Analyses (PCA) were made to mark out the correlations between the different parameters obtained in different seasons and in various sampling points, as well as the correlations between the physicochemical parameters and the WQI. In order to assess the Danube water quality, the following physicochemical parameters were taken into account: pH, BOD, COD, DO, P-PO 4 3-, N-total, N-NO 3 -, N-NO 2 -, N-NH 4 + , SO 4 2-, Cl -, Cr-total, Pb 2+ , Cd 2+ , Ni 2+ , Fe-total, Mn-total, Zn 2+ , As 2+ . The water samples were collected from 5 sampling points situated upstream, along and downstream the city of Galati for a period of 12 seasons, starting from the autumn of 2010 and continuing up to the summer of 2013. The water quality assessment was made according to the water quality index (WQI). The conclusions regarding the influence of the anthropogenic activity on water quality could be drawn by observing the water quality variations as conditioned by the sampling points and the nearby industrial or municipal sites. Given the fact that there were more monitoring points in the envisaged area, the water quality assessment was made by taken into consideration the data resulting from all the sampling points.
Conference Paper
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Full-text available ABSTRACT: The objective of the present work is to evaluate the wind energy potential in the western Black Sea region by considering 11 years (1999-2009) of wind data. The local wind conditions at 10 m and 80 m height are evaluated by considering data coming from several offshore weather stations and also from the European Centre for Medium-Range Weather Forecasts (ECMWF). Subsequently the effectivity of two different types of wind turbines will be assessed in the area targeted. The seasonal and spatial distribution of the energy distribution is assessed in terms of power density and theoretical power output from the Vestas V90-3.0 and Siemens 2.3-93 wind turbines. The average wind conditions at 80 m height based on the meteo dataset indicate the Romanian area to be more energetic during the winter season with an average wind speed of 12 m/s and a power density of 1703 W/m2. On the other hand, the model dataset indicate the Ukrainian nearshore area to be more energetic also during the winter season, with an average wind speed of 9.8 m/s, a power density of 922 W/m2 and much higher wind conditions register in the offshore area. Finally, the regional wind energy resources at 80 m height are compared on a global scale with the similar ones from locations in which offshore wind farms already operate or are planned to be develop. The main conclusion coming from the present work would be that the western Black Sea represents a promising area for the wind energy extraction. KEY WORDS: renewable energy; wind; power density; western Black Sea
Conference Paper
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The Black Sea pollution has now reached an unprecedented level, the biggest polluter being the hydrocarbons. An important role in oil pollution is played by the tanker accidents. The severe marine accidents produced as a result of collisions, contact, grounding, structural failure, fire and explosions, affect aquatic and coastal ecosystems and on-shore human social activities, the crew life and ship itself. The consequences and likelihood of each risk determine the risk level. Risk assessment is a complex process involving hazard identification, its consequences and likelihood that those consequences may occur. This is achieved through critical analysis of the available data concerning the marine accidents. To assess these risks, International Maritime Organisation (IMO) has developed a structured and systematic methodology for a formal safe assessment (FSA). The aim of the work proposed herewith is to present the steps of the risk assessment methodology. The risk assessment results stay on the basis of the risk management and help to the adoption of measures for the risk control, prevention and reduction in operating ships at sea. Adoption of the risk management throughout the life cycle of ships, design and operation can provide the best practices for reducing risks in the maritime transport of petroleum products.
The main objective of the present work is to provide a more comprehensive picture of the wind patterns in the Black Sea basin. The analysis is based on 14 years of data (1999–2012) coming from both measurements and reanalysis model wind fields. A first perspective of the wind conditions in the coastal environment of the Black Sea is given by considering data from several offshore weather stations that operate in the western sector of the sea. The above analysis is completed using remotely sensed data as well as wind fields from two atmospheric models operated by the European Centre for Medium-Range Weather Forecasts and the U.S. National Centres for Environmental Prediction. Beside a more complete image of the wind climate in the area targeted, the results show that in general a good agreement is encountered between the measured data and the numerical models as regards the overall spatial and seasonal evolutions of the wind conditions. The results indicate also that significant energetic wind conditions more often occur in the western part of the sea. These appear to be very similar with those from several offshore locations where wind farms already operate. Following this observation, and using the same data set, direct comparisons with four such locations from the Baltic Sea are also performed. The main conclusion of the work is that the coastal environment of the Black Sea, and especially that from its western side, is appropriate for wind energy extraction.
The present work carries out a parallel analysis between the performances and, on the other hand, of the restrictions of two different model systems designed to assess the nearshore circulation. These are SHORECIRC, which is a widely known general prediction system for nearshore circulation and ISSM (the Interface for SWAN and SURF Models). SHORECIRC is a quasi-3D model that combines a numerical solution for the depth-integrated 2D horizontal momentum balance equations with an analytical solution for the 3D current profile. The restrictions of the model are very mild and the basic circulation equations solved can therefore in general be considered very accurate. In addition, such a model catches the non-linear feedback between wave generated currents and the waves that generate them. The ISSM system is composed of a MATLAB GUI in the foreground, which directs the integration of the SWAN shallow water wave model with a I D surf model in the background. The present study performed in a non conventional coastal environment attempts to find out the limits of the numerical models for the coastal circulation and to balance the advantages and disadvantages brought by the two systems compared