Regime Analysis with Numerical Modelling of Wave Dynamics and

Determination of Potential Flood Zones in Chancay Bay, Peru

Jose Soto

, Emanuel Guzman

and Carmela Ramos

Facultad y Escuela de Ingeniería Civil, Universidad Peruana de Ciencias Aplicadas, Av. Prolongación Primavera 2390,

Santiago de Surco, Lima, Peru

Keywords: Chancay Bay, Wave Dynamics, Dihidronav, Delft3d Wave, Wave Modeling.

Abstract: The wave dynamics in Chancay Bay is represented by the Delft3D numerical model, whose application is

referred to the propagation and calibration of the waves in the WAVE module through the Copernicus ERA5

database and comparison with field measurements of the hologram of the Directorate of Hydrography and

Navigation. (DIHIDRONAV) for medium and maximum regime conditions, in order to determine the Run

Up of waves in areas of human development with the Van Der Meer and Stem methodology. In this sense,

the topography of the ALOS PALSAR sentinel was extracted to determine the flood zones within the coast,

whose representation is given by the length and height of the wave reached.

1 INTRODUCTION

The study of wave dynamics in coastal areas is carried

out through numerical models whose interest is

multipurpose decision-making management. This is

why characterizing the waves in coastal areas is a

mandatory task, but one that is frequently limited due

to its complexity of execution and lack of information

from field and/or satellite measurements.

This is reflected in many investigations that,

through statistical adjustments, calibrate the numerical

models until a reliable approximation is obtained

through data collection and is compared with in situ

measurements to be adjusted using correction models

(Wang et al., 2022). On the other hand, within coastal

studies, understanding the interactions of waves, tides

and currents in coastal regions has become a fundamen-

tal aspect to develop best practices in numerical

modeling methodology (Pinault et al., 2020) (Prakash

et al., 2021). Likewise, there are different quasi-3D

models, of which Delft3D, Mike21, TELEMAC and

SWAN stand out. These 4 models are commonly used

by researchers to perform analysis of wave behavior. Of

those mentioned, Delft3D presents good results, since

this software allows the coupling of modules that allow

establishing an expansion in the analysis and reducing

or optimizing modeling time (Villagrán et al., 2022).

https://orcid.org/0009-0002-6315-0228

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Therefore, it is feasible to establish a before and after

that allows generating warnings or effective solutions

to coastal hazards (Leach et al., 2021).

Therefore, in this article the wave characterization

will be carried out with the medium regime method of

Chancay Bay, Figure 1, for three numerical modeling

scenarios in the Delft3D software using satellite

information from the current year and nautical chart of

Chancay Bay in its latest version, as well as data from

Copernicus ERA5 over a period of 30 years and field

measurements requested from the Directorate of

Hydrography and Navigation (DIHIDRONAV) in its

latest version.

Figure 1: Study Zone of Chancay.

Soto, J., Guzman, E. and Ramos, C.

Regime Analysis with Numerical Modelling of Wave Dynamics and Determination of Potential Flood Zones in Chancay Bay, Peru.

DOI: 10.5220/0012631700003696

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 10th International Conference on Geographical Information Systems Theory, Applications and Management (GISTAM 2024), pages 51-61

ISBN: 978-989-758-694-1; ISSN: 2184-500X

Likewise, this article aims to determine the

potential flood zones through a numerical model and

compare its results with data taken in the field, as well

as a tentative location of coastal structures.

2 METHODOLOGY

2.1 Tools

Delft3D is a numerical modeling software widely used

in coastal zone research, since very good results are

obtained, and it is easy to acquire through educational

licenses valid for up to one year. Likewise, Delft3D

has the WAVE module which simulates the evolution

of waves generated by wind in coastal areas (Deltares,

2023). This module models the propagation of waves

and waves generated by wind, which in turn considers

the effects generated by wave diffraction and

refraction. As input values, the bathymetry of the area

in UTM coordinates and height, period and wave

direction data are assigned.

2.2 Materials

To carry out numerical modeling in the medium

regime, in situ information from DIHIDRONAV for

the years 2008 and 2009 from the ADCP Nortek AS

(R) has been used, as well as oceanographic data from

Copernicus ERA 5.

In the case of bathymetric information, the nautical

chart of Chancay Bay was acquired in .TIF format

from DIHIDRONAV and updated satellite

information of the coastline from Google Earth.

2.3 Method

The mean regime method is used to statistically

classify the highest and average values of a time series

for each cardinal direction of wave propagation,

Figure 2. This is possible by programming in RStudio

and MATLAB. As it is encrypted information, the

data is extracted in RStudio in .xlsx format and in

MATLAB the classification is provided as a result

with the configuration indicated in the code.

2.4 Data Used

The nautical chart of Chancay Bay is digitized the

depths and coastline, while the current satellite

information is digitized the coastline. Likewise, with

the data collected for a period of more than 30 years

of Copernicus ERA5, the extraction and classification

Figure 2: Processing flow diagram and obtaining medium

regime classification.

procedure are carried out with the medium regime

method. On the other hand, the ADCP's in situ data

was already classified. With the information available,

three modelling cases are classified in different

conditions for Chancay Bay, as a result, they are the

following.

The first case is a regime analysis for a wave of

more than 30 years with bathymetric data from the

nautical chart of Chancay Bay.

Then, a regime analysis for a wave from the years

2008 and 2009 with bathymetric data from the

Chancay nautical chart.

Finally, a regime analysis for a wave of more than

30 years with satellite bathymetric data to date.

2.5 Wave Characterization in Deep

Waters

The general characteristics such as cardinal direction

and wave height in shallow waters, Figure 3, that

predominate in Chancay Bay are coming from the

south with an average height of between 1.3 and 2.1

Figure 3: Wave rose in shallow water of Chancay bay

(S11°34'17" W77°16'1.99").

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

meters, and less frequently, but of greater height

between 2.9 and 3.7 meters. There are also wave

heights of between 3.7 to 4.5 meters and higher, which

are not visible due to their low frequency, but are not

non-existent.

Now that the general characteristics are known, in

Table 1, the classified wave data for the 1st and 3rd

modeling case is observed, while in Table 2, the

classified wave data for the 2nd modeling case is

observed. In both, the average and maximum cases are

handled for each cardinal direction.

Table 1: Average regime for wave data for a period of more

than 30 years from Copernicus ERA5.

Case

Dir

Hs (m) Tp (s)

Case

Dir

Hs (m) Tp (s)

WSW

1.54 10.82 5

1.69 11.12

2 1.97 12.00 6 3.48 16.04

1.92 8.66 7

SSW

1.76 10.12

4 3.71 13.21 8 4.23 16.09

Table 2: Average regime for wave data from the

DIHIDRONAV ADCP for the years 2008 and 2009.

Case Dir Hs (m) Tp (s)

1.92 8.81

2 2.66 13.21

1.71 10.89

4 3.06 14.13

SSW

1.69 9.99

6 2.83 14.46

2.6 Numerical Modeling

The Delft3D model operates within a discrete domain,

defining a particular calculation region through a

computational mesh. The RGFGRID module prepares

Figure 4: Computational mesh calculation in Chancay Bay.

this mesh, and the QUICKIN module uses triangular

interpolation to determine depths based on digitized

bathymetry.

Likewise, Figure 4 shows the computational

domain for numerical modelling. On the other hand,

Table 3 presents the geometric characteristics of said

domain.

Table 3: Average regime for wave data from the

DIHIDRONAV ADCP for the years 2008 and 2009.

Shallow waters

Computational grid

Long (km) 9.53

Width (km) 7.72

dx (m) 15.00

dy (m) 20.00

Angle (°) 24.00

Finally, in the WAVE module, the input values of

height, period, and direction from Tables 1 and 2 are

entered according to the direction of wave

propagation.

3 RESULTS AND DISCUSSIONS

Of the three modeling cases, the first case, according

to Table 1, gives 8 results for the west-southwest,

south, southwest, and south-southwest directions in its

predominant and maximum conditions. Of which, the

maxims will be highlighted, as they are most relevant

to the knowledge of potential flood zones.

Figure 5, Figure 6, Figure 7 and Figure 8 show the

results for the maximum wave conditions of Chancay

Bay from the first modeling case. For the west-

southwest direction the following result was obtained.

Figure 5: Maximum condition in west-southwest direction

in Chancay Bay.

Regime Analysis with Numerical Modelling of Wave Dynamics and Determination of Potential Flood Zones in Chancay Bay, Peru

For the south direction in maximum wave

conditions of Chancay Bay.

Figure 6: Maximum condition in south direction in Chancay

Bay.

Likewise, for the southwest direction in maximum

wave conditions of Chancay Bay.

Figure 7: Maximum condition in southwest direction in

Chancay Bay.

Also, for the south-southwest direction in

maximum wave conditions in Chancay Bay.

Figure 8: Maximum condition in a south-southwest

direction in Chancay Bay.

The second case, according to Table 2, gives 6

results for the south, southwest, south-southwest

directions. Of which, the maxims will be highlighted;

Figure 9, Figure 10 and Figure 11 for what was

previously said, to know the potential flooding zones.

Then, for the south direction in maximum wave

conditions of Chancay Bay, the following result was

obtained.

Figure 9: Maximum condition in a southerly direction in

Chancay Bay.

Additionally, for the southwest direction in

maximum wave conditions of Chancay Bay.

Figure 10: Maximum condition in southwest direction in

Chancay Bay.

Also, for the south-southwest direction in

maximum wave conditions of Chancay Bay.

This second modeling case, since it does not have

an updated bathymetry and current in situ wave data,

except for the ADCP whose measurement is valid

until 2009, which can be validated through ERA5 data

from 2008 to 2009, is calibrated in function of the

bottom friction coefficient of the model until

obtaining approximate results.

Based on the results of the second modeling case,

the wave Run Up is estimated for three points in the

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

Figure 11: Maximum condition in a south-southwest

direction in Chancay Bay.

area that are within or close to the surf zones. These

areas were chosen because they have the highest

concentration of human activity, such as commerce

and fishing. Of the analysis points mentioned, only the

first three that are presented in Figure 12 and Figure

13 are considered.

Figure 12: Analysis points to estimate the Run Up of the

wave in the south direction.

Figure 13: Analysis points to estimate the Run Up of the

wave in the south-southwest direction.

The following Table 4 displays the parameters

obtained for said calculation, which are a function of

the bathymetry depth, height, and wave distance at

said point with respect to the coast from the surf zone,

which can be seen in Figure 12-13 and summarized in

Table 4.

Table 4: Summary of distances, depth, and heights of the

points of interest of the Run Up calculation under maximum

conditions.

Dir

Poin

Model

Distance

(m)

Model

Depth

(m)

Model

Hs (m)

Regime

Analysis

Hs (m)

Regime

Analysis

(s)

1 362.40 2.90 1.88 2.66 13.21

2 217.71 2.90 1.70 2.66 13.21

3 135.42 2.90 1.25 2.66 13.21

- - - - - -

SSW

1 80.90 1.40 0.46 2.83 14.46

2 78.00 1.40 0.85 2.83 14.46

3 84.02 1.40 0.74 2.83 14.46

Finally, the third case, based on Table 1, gives, like

the first modeling scenario, 8 results for the west-

southwest, south, southwest, and south-southwest

directions. This will also highlight the results of the

maximum conditions, as they are more relevant to the

knowledge of potential flood zones.

The difference between the first and third

modeling cases is the change in the bathymetry and

coastline used. The first specifies the use of the

nautical chart until its last update, which dates to 2005,

while the third uses the same bathymetry of the

nautical chart with the current coastline provided by

Google Earth.

In Figure 14, Figure 15, Figure 16, and Figure 17

the results of the third case of numerical modeling for

Chancay Bay in maximum conditions will be seen.

So, for the west-southwest direction in maximum

wave conditions of Chancay Bay.

Figure 14: Maximum condition in west-southwest

direction in Chancay Bay.

Regime Analysis with Numerical Modelling of Wave Dynamics and Determination of Potential Flood Zones in Chancay Bay, Peru

For the south direction in maximum wave

conditions of Chancay Bay.

Figure 15: Maximum condition in a southerly direction in

Chancay Bay.

For the southwest direction in maximum wave

conditions of Chancay Bay.

Figure 16: Maximum condition in southwest direction in

Chancay Bay.

For the south-southwest direction in maximum

wave conditions of Chancay Bay.

Figure 17: Maximum condition in a south-southwest

direction in Chancay Bay.

Although the results presented are from scenarios

with conditions that vary the bathymetry, coastline

and wave reanalysis of ERA5, the advantages and/or

disadvantages of these range from modeling in context

to not having many in situ measurements. Table 5

presents the comparison between these modeling

scenarios according to the mentioned conditions.

Table 5: Summary of the characteristics and usefulness that

it would have in a future numerical modeling of Chancay

Bay.

Desc

Case 1 Case 2 Case 3

Bathymetry

Nautical

chart

outdated

compared to

the year in

which this

research was

carried out.

Nautical chart

outdated

compared to

the year in

which this

research was

carried out.

Outdated nautical

chart, but with an

updated coastline

compared to the

year in which

this research was

carried out.

In situ measurements

Outdated in

situ

measurement

s compared

to the year in

which this

research was

carried out.

In situ

measurements

updated with

the bathymetric

information of

the model

made.

In situ

measurements

outdated with

respect to the

year in which

this research was

carried out.

Coastal line

Coastline

outdated as

of the year

this research

was

conducted.

Coastline

updated to the

year in which

the bathymetric

and

measurement

information of

the model

carried out was

collected.

Coastline

updated to the

year this research

was carried out.

Utility

It serves as a

model for

validation

only if

satellite

images from

recent years

are available.

It serves as a

model for

validation only

if satellite

images from

recent years are

available.

It serves as a

model for

validation only if

satellite images

from recent years

are available.

In this sense, the advantages of carrying out a

medium regime analysis in Chancay Bay can be traced

back to the validation of future scenarios with the use

of primary information available to date. However,

this limits the information regarding the timing of the

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

waves, since in recent years Peru has presented

climatic phenomena such as “Fenómeno El Niño

Costero” and “Ciclón Yaku” that alter the wave

regime. Therefore, future modeling would require

greater computational scope. That is, cover larger

areas for wave propagation in areas that do have

information from later years.

With emphasis on the aforementioned idea, in the

country of Peru, research titled "Simulación de

transporte de sedimentos en la bahía Ferrol,

Chimbote" was carried out, whose numerical model

was based on the concept of selecting the most

representative wave cases, validation of the numerical

model with DIHIDRONAV holograph measurements

and future prediction for the selected conditions

(Ramos, 2017). As a result of its calibration and

validation, it used the same energy dissipation

calibration parameters to obtain a predictive model for

a time of 20 years in the future.

4 ANALYSYS OF RESULTS

For the first modeling case, the following Delft3D

results were obtained referring to the wave height in

Table 6.

Table 6: Summary of results obtained from the medium

regime and ADCP of the first modeling case.

Dir

Measuremen

Predominant

Condition

Maximum

Condition

(m)

Tp (s)

(m)

Tp (s)

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.49 - 1.96 -

Error (%) 14.62 - 6.67 -

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.50 - 2.85 -

Error (%) 15.38 - 35.71 -

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.52 - 3.54 -

Error (%) 16.92 - 68.57 -

SSW

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.44 - 3.90 -

Error (%) 10.77 - 85.71 -

As can be seen, there are wave heights that are

above the ADCP in situ measurement data, and some

are even higher than 50% of the real value, which are

the southwest and south-southwest directions.

On the other hand, in the second modeling case,

the following Delft3D results were obtained referring

to the wave height in Table 7.

Table 7: Summary of results obtained from the medium

regime and ADCP of the second modeling case.

Dir Measurement

Predominant

Condition

Maximum

Condition

(m)

Tp (s)

(m)

Tp (s)

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.50 - 2.05 -

Error (%) 15.38 - 2.38 -

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.53 - 2.92 -

Error (%) 17.69 - 39.05 -

SSW

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.38 - 2.60 -

Error (%) 6.15 - 23.8 -

As can be seen, the wave heights obtained by the

Delft3D model are very close to the in-situ

measurement. Except for the southwest and south-

southwest directions that exceed in a range of 20-40%.

Likewise, in the third modeling scenario, the

following Delft3D results were obtained, also

referring to wave height, Table 7.

Table 8: Summary of results obtained from the medium

regime and ADCP of the third modeling case.

Dir Measurement

Predominant

Condition

Maximum

Condition

Hs (m) Tp (s) Hs (m) Tp (s)

WSW

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.47 - 1.95 -

Error (%) 13.08 - 7.14 -

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.47 - 2.79 -

Error (%) 13.08 - 32.86 -

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.50 - 3.52 -

Error (%) 15.38 - 67.62 -

SSW

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.42 - 3.88 -

Error (%) 9.23 - 84.76 -

Based on Table 6, Table 7 and Table 8, exceedance

patterns are observed with respect to the wave height

measured by the ADCP in the southwest and south-

southwest directions, which are greater than 50% with

respect to the actual measurement value.

Although the 3 modeling cases can be calibrated in

the same Delft3d WAVE model, it was decided to

work only with the second case, since it is the one that

works with all the most current data officially, both

bathymetry, measurement, and line coast.

Regime Analysis with Numerical Modelling of Wave Dynamics and Determination of Potential Flood Zones in Chancay Bay, Peru

Therefore, the Run Up calculation based on Table

IV and the methodology of Van Der Meer and Stam

gave the following results, Table 9, after having done

the calibration.

Table 9: Wave Run Up calculation with the Van Der Meer

and Stam formulation for maximum wave conditions

considering the tide level.

Method S SW SSW

Van

Der

Meer y

Stam

(1992)

Ru 10%

(m) =

3.70

Ru 10%

(m) =

Ru 10%

(m) =

1.60

Ru 5%

(m) =

4.10

Ru 5%

(m) =

Ru 5%

(m) =

1.70

Ru 2%

(

)

4.70

Ru 2%

(

)

Ru 2%

(

)

1.90

Ru 10%

(

)

3.40

Ru 10%

(

)

Ru 10%

(

)

1.20

Ru 5%

(m) =

3.80

Ru 5%

(m) =

Ru 5%

(m) =

2.40

Ru 2%

(

)

4.30

Ru 2%

(

)

Ru 2%

(

)

2.60

Ru 10%

(

)

2.80

Ru 10%

(

)

Ru 10%

(

)

2.00

Ru 5%

(m) =

3.10

Ru 5%

(m) =

Ru 5%

(m) =

2.20

Ru 2%

(m) =

3.40

Ru 2%

(m) =

Ru 2%

(m) =

2.40

In this Table 9, the wave Run Ups were obtained

for the probability of occurrence of 10%, 5% and 2%

for the 3 selected points in the south and south-

southwest directions. In the southwest there were no

important surf zones, so they are not considered. Of

these, the wave heights with the highest percentage

represent heights in normal conditions, while a lower

percentage represents heights in maximum conditions.

Additionally, the tide level is considered, the

difference between the highest and lowest level being

the result of this, which is added to the Run Up

obtained, which by polling DIHIDRONAV tide tables

gives a value of 0.97 m.

The south direction presents higher waves

compared to the south-southwest direction, despite

this both represent a danger to human activity in

coastal areas, since the heights can exceed terrain

levels greater than 4 meters and a large part of the

shops or points of port activity in the area are located

near the coastline whose elevation is 0 meters.

The wave heights obtained do not mean that they

will enter the coastal zone maintaining the same height

in magnitude, these will be reduced until they reach or

exceed the terrain levels according to the wave height

obtained, but with minimum wave heights that may be

called sheets of water. However, its height may be

minimal, but its extension within the coastal zone may

be wide. This suggests that the impact of the wave

alone should not be underestimated because of its

apparently small size.

In that sense, flood zones are estimated through

interpolation between contour lines of the Alos Palsar

DEM and elevations from Google Earth since the

elevations of the DEM are over scales of the real

height.

Table 10 shows the summary of the interpolation

carried out, from which a proportional ratio was

detected between the Google Earth elevations and the

Alos Palsar DEM.

Table 10: Summary of the elevation interpolation process

between Alos Palsar and Google Earth.

INTERPOLATION TO ALOS PALSAR

Goo

le Earth DEM Alos Palsar

Elevation (m)

1.00

Elevation (m)

21.00

2.00 23.00

3.00 25.00

4.00 27.00

5.00 29.00

6.00 31.00

Figure 18: Numerical modeling flowchart of DELFT3D WAVE software to determine flood zones.

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

Based on the table shown, the range of the wave

Run Up can be determined in the areas of the coast of

interest.

Additionally, Figure 18 presents a numerical

modeling flowchart for determining flood zones in

the context of Chancay Bay. It can be noted that with

the recent growth in the use of artificial intelligence,

the use of predictive models of artificial neural

networks (ANN), calibration and validation in a

future context would be interesting to carry out.

However, for the present study it would not be useful,

but rather useful for training.

Below, the flood zones obtained from numerical

modeling are presented, which considers the

elevations of the internal coastal zone, in the

maximum conditions for the south and south-

southwest directions, as seen in Fig. 19 and 20.

Figure 19: Flood zones in the coastal area of Chancay for

the maximum condition in the south direction.

Figure 20: Flood zones in the coastal area of Chancay for

the maximum condition in the south-southwest direction.

Based on Figure 19 and 20, it is determined that

the range of the waves extends to levels of 4 and a

maximum of 5 meters in elevation for the south

direction.

The wave at points A), B) and C) of Figure 21 in

a southerly direction travel between levels of 4 to 5

m, with lengths of the order of 38, 93 and 97 m up to

reach wave heights of 0.15 m. That is, from the

Figure 21: Flood zones with representative values for south

direction.

Figure 22: Flood zones with representative values for south-

southwest direction.

estimated elevation of Table 9. Around 92% of it

dissipated during that journey, but with great scope.

On the other hand, based on the flood zone in

Figure 22 in the south-southwest direction, it is

determined that the reach of the waves extends below

levels of 2 m, but that they reach into the coast

between the 20 and 21 m at points B) and C) with

significantly low wave heights. Beyond the coast,

wave heights are close to 0, which indicates that they

dissipate completely beyond 3 m of terrain elevation.

Therefore, the southern direction zones contain

greater relevance than the south-southwest direction

due to its flooding potential due to the longitudinal

reach within the coast and with wave heights of the

order of 0.2 m that exceed that of the south-southwest

by 96%. Therefore, an attempt at coastal protection

structures, Figure 23, can be proposed in this and

other stretches of the coast for future research.

Regime Analysis with Numerical Modelling of Wave Dynamics and Determination of Potential Flood Zones in Chancay Bay, Peru

Figure 23: Tentative proposal for coastal protection

structures.

5 VALIDATION

Based on the result of the second modeling case,

calibration was performed with respect to the bottom

friction coefficient of the JONSWAP formulation.

This is one of the terms that condition the dissipation

of wave energy, the other terms are called

Table 11: Summary of results obtained from the calibration

process of the background friction coefficient.

Dir Measurement

Maximum Condition

Hs (m)

Bottom friction

coefficient

0.07 0.08 0.11 0.14

In Situ 2.10 2.10 2.10 2.10

Delft3D 2.92 2.90 2.87 2.84

Error (%) 39.05 38.10 36.67 35.24

SSW

In Situ 2.10 2.10 2.10 2.10

Delft3D 2.60 2.59 2.56 2.53

Error (%) 23.81 23.33 21.90 20.48

Bottom friction

coefficient

0.19 0.23 0.29 0.38

In Situ 2.10 2.10 2.10 2.10

Delft3D 2.80 2.76 2.70 2.63

Error (%) 33.33 31.43 28.57 25.24

SSW

In Situ 2.10 2.10 2.10 2.10

Delft3D 2.49 2.45 2.4 2.33

Error (%) 18.57 16.67 14.29 10.95

Bottom friction

coefficient

0.50 0.71 0.83 1.04

In Situ 2.10 2.10 2.10 2.10

Delft3D 2.53 2.36 2.27 2.13

Error (%) 20.48 12.38 8.10 1.43

SSW

In Situ 2.10 2.10 - -

Delft3D 2.24 2.08 - -

Error (%) 6.67 0.95 - -

Whitecapping and Breaking induced by the change in

depth (Alpha-Gamma). The last mentioned are

limited to the proposed study, due to the scarce

information on wave data.

Table 11 shows the table of bottom friction

coefficient values through the iterations carried out

for calibration. Then, the values are close to those

measured in the field, with the southwest and south-

southwest coefficients being 1.04 m2s-3 and 0.71

m2s-3, respectively. Therefore, the new calibrated

and compared measurement values are as follows.

Table 12: Summary of results obtained from the calibration

process of the background friction coefficient.

Dir Measurement

Predominant

Condition

Maximum

Condition

Hs (m) Tp (s) Hs (m) Tp (s)

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.50 - 2.05 -

Error (%)

15.38

2.38

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.50 - 2.13 -

Error (%)

15.38

1.43

In Situ 1.30 12.60 2.10 17.30

Delft3D 1.42 - 2.08 -

Error (%)

9.23

0.95

Table 12 shows how the results in maximum

condition for the southwest and south-southwest

directions are in the error range of 0% to 2% with

respect to the ADCP measurement value.

6 CONCLUSIONS

The wave dynamics in Chancay Bay were studied for

a period of 32 years, in which the most notable result

of the research is the flood zones that put the

population at risk.

To this end, modeling cases of the wave

propagation of Chancay Bay were selected to

determine the variational percentages with respect to

the ADCP measurement from the medium regime

technique to calibrate and determine the potential

flooding zones of the Chancay Bay.

The results show that the flood zones reach wave

heights of between 0.10 to 0.15 m, but with a large

extension towards the population in the southern

direction and these even exceed those in the south-

southwest by 96%, thus emphasizing to the

possibility of placing coastal protection structures for

future research.

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

Finally, a large amount of data is not required to

carry out the methodology suggested in this article.

To carry out an investigation of this style, it is

sufficient to have the bathymetry of the area through

nautical charts, wave data that can be extracted from

COPERNICUS ERA5 in large time series and short-

term in situ wave measurements that can be used for

calibration and validation of the numerical model.

However, the research results can continue to be

improved through information from oceanographic

buoys from surrounding areas, which covers more

modeling area and more robust scenarios, but with

greater computational cost due to its modeling

extension.

Therefore, the methodology used can be

replicated in coastal areas that do not have much

information on wave measurements, as is the case of

the Peruvian coast and specifically the Chancay Bay

as well as other parts of the world.

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Regime Analysis with Numerical Modelling of Wave Dynamics and Determination of Potential Flood Zones in Chancay Bay, Peru