chiriqui hydrological-study old boundary

8/10/2019 Chiriqui Hydrological-Study Old Boundary

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1. .................................................................................................................................................... 3

2. A A A .................................................................................... 3

3. BA AAA ........................................................................................................ 4

3.1 A B ............................................................................................................................. 4

3.1.1 .................................................................................................................................................. 4

3.1.2 B ....................................................................................................................... 5

4. AA AA .................................................................................................................................. 7

4.1 ............................................................................................................................................................. 7

4.2 .................................................................................................................................................... 9

4.3 .............................................................................................................................................................. 10

4.4 .......................................................................................................................................... 11

5. A AA .................................................................................................................. 12

5.1 A ......................................................................................................................................... 12

6. A AA .................................................................................................................................... 14

6.1 ............................................................................................................ 17

7. .......................................................................................................................................................... 19

8. A ............................................................................................................................... 22

9. BBA ..................................................................................................................................................... 23


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1. INTRODUCTION

The present study aims to determine the relevant hydrological aspects applying methodologies grounded on

hydrological, statistical and mathematical processes globally recognized for the purpose of providing

hydrological parameters required for the construction of Solar Project.

The information on meteorology and hydrology of the study area was provided by the Department of

Hydrometeorology of the Empresa de Transmisin Elctrica, S.A. (ETESA) which, together with recent

studies, we proceeded to the selection and data depuration in a properly and reliable manner.

The 44 MW Solar Project, will be located in the district of Chiriqui, Chiriqui, Republic of Panama, in Basin

#108, denominated Chiriqui River in the Panamanian Pacific, which has a drainage area to the mouth of the

Sea of 1995.9 km2. The major tributary or tributaries of this basin are: Caldera River, Los Valles River, Esti

River and Gualaca River.

2. GENERAL LOCATION AND DESCRIPTION OF PROJECT

The site of the 44 MW Solar project is located in the western region of the Republic, in the township ofChiriqui, Chiriqui district and province of Chiriqui, Republic of Panama. The PV projects study area is in the

lower basin of the Chiriqui River in the Pacific slope. The project site is located approximately 300 meters east

from the Interamerican Highway Bridge over the Chiriqu River.


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3. CHIRIQUI RIVER BASIN CHARACTERIZATION

Chiriqu River Basin is located in the province of Chiriqu, in the western part of the Republic of Panama,

between latitudes 8 15and 8 53 North Latitude and 82 10and 82 33 of the West Longitude.

The drainage area is 1995.9 km and the length of the main river is 130 km.

The Chiriqui Rivers main tributaries are: the Caldera , Los Valles, Esti , Gualaca and those born on the

slopes of Baru Volcano as rivers Cochea , David, Mahoe , Suns and Platanal .

Three hydroelectric schemes affect the flow records of the stations of the Chiriqui River; David, La Esperanza

and Paja de Sombrero. The system Caldera diverts with a canal, waters of the Caldera River to the Caldera

Plant, then discharging it into the Cochea River. This occurred during the period at which the Hydroelectric

Plant of Caldera was operating, (from 1955 to 1979). Currently, the waters of the Cochea River are diverted by

a channel to the Dolega Plant, subsequently discharging in the David River. Since March 1984, with the

closing of gates and the startup of the plant Edwin Fabrega (Fortuna), waters of the Chiriqui River are diverted

through a tunnel to the machine house of this plant and are then discharged into the Buenos Aires creek,

which is a tributary of the Chiriqui River.

The basin records an average annual rainfall of 3,978 mm in the upper part of it, while annual rainfall varies

between 3,330 and 7,000 mm / year. 92 % of the rainfall occurs between the months of May and December

and the remaining 8 % was recorded between January and April.

3.1 Area of the Chiriqui Basin

3.1.1 Type of drain

The drainage pattern of the Chiriqui River basin is mainly dendritic type, indicating the presence of

homogeneous soils and geological materials like soft sedimentary rocks, volcanic tuffs and glacial deposits.

However, locally some variants of this locally drainage pattern are presented, such as the rectangular and the

angled drainage pattern originating from faults, fractures and binding systems of the most resistant geological

material.


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3.1.2 Drainage of the Project Basin

As shown in Map 1, the polygon on which the project is developed, is located about 300 meters from and

parallel to the downstream left bank of the Chiriqui River. And very close to the southern corner of the polygon

passes the Berrona creek, which flows into the Chiriqui River. From the map it can be observed that the

waters of the project site drain into the Quebrada La Berrona (La Berrona Creek), which eventually drains into

the Chiriqui River.

The land within the Project has few elevations with slopes less than 1%.

Concerning pluvial flooding- from rainfall on surface, there two drainage basins upstream the PV project that

could potentially affect the PV plant:

Sub-Basin 1 denominated CUENCA 1 with 48.2 Ha

Sub-Basin 2 denominated CUENCA 2 with 15.2 Ha

Currently the drainage runoff from these sub-basins, before entering the project area, is collected by drainage

ditches adjacent to the sides of the Interamerican Highway and eventually discharges into the Chiriqui River.

Therefore, we come to the conclusion that there is no danger for the PV project from incoming drainage runoff

as there is an existing drainage system in the area, protecting the Interamerican Highway, as well as the PV

plant downstream of it.


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Map1. Map of Sub-Basins of the Project (denominated CUENCA 1 and CUENCA 2 on Map)


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4. CLIMATOLOGICAL ANALYSIS

4.1 Climate

The PV projects study area is located at the lower part of the Chiriqui River. The Chiriqu Rivers basin in its

upper part is influenced by the climate produced by the presence and altitude of the Baru volcano.

According to the Kppen classification, the project site is located between two climate zones: Tropical

savanna climate and Humid tropical climate. (See Map 2).

1) Tropical savanna climate (Awi) in the lower part of the basin: Rainfall is less than 2500 mm; ischaracterized by a long dry season with monthly totals lower than 60 mm during the northern hemisphere

winter; the average temperature of the coldest month is greater than 18 C, the difference between th e mean

temperature of the warmest month and the coldest month is less than 5 C.

2) Wet tropical climate (Ami): Annual precipitation is greater than 2500 mm, one or more months with

rainfall less than 60 mm; the average mean temperature of the coldest month is below 18C. The differe nce

between the mean temperature of the warmest month and the coldest month is less than 5C.


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4.2 Temperature

Thermal analysis on Basin #108, which is the Chiriqui River Basin, is represented by 3 stations: by its

elevation in its upper area will be represented by the stations of Caldera Plantand Los Naranjos, located at

920 and 1200 mamsl respectively, the Sombrero de Paja station at 388 mamsl representing the middle zone

and the David station representing the lower part.

High Zone: The analysis of the temperature records of the high region of Basin #108, obtained from the

stations of Caldera Plant and Los Naranjos, indicate a great uniformity of the temperature regime in its

environment. In Caldera Plant, the average annual oscillation, i.e. the temperature difference between the

hottest month and the coldest is 1.8 C, 21.7 C for the warmer months (March, April) and 19.9 C f or the

coldest (October). The average annual temperature is 20.7 C; the annual mean maximum is 25.0 C and theminimum 16.5 C so that the average daily oscillat ion is 8.5 C. In the Station of Los Naranjos, temperature is

stable, in a manner that its regime is extremely uniform throughout the year with both influence of the trade

winds from the northeast and southwest due to its height above sea level (1200 m) and boundary position to

the Central Mountain Range (Cordillera Central), and its annual average oscillation reaches only 1.1 C, the

warmest month with 20.9 C in May and the coldest month with 19.8 C in January. The average annual

temperature is 20.4 C, the average maximum temperature is 25.4 C and the minimum is 15.7 C, so t hat

the average daily oscillation is 9.7 C. 1

Middle Zone:The analysis of the temperature record in the middle region of the basin was obtained from

Sombrero de Paja station and great uniformity in thermal regime is observed as throughout the Pacific side of

Panama. In Sombrero de Paja, the average annual oscillation reaches 2.2 C, with 24.1 C for the co ldest

month (October) and 26.3 C for the hottest month (April). The average annual temperature is 25.0 C, the

average maximum temperature is 29.8 C and of the minimums, 20.3 C so that we obtain an average dai ly

oscillation of 9.5 C. 2

Lower Zone: For the analysis of the lower area, which is precisely where the Project area is located, the

David station records are used.According to the last 30 years of record, the average annual temperature is 27.20 C. The minimum

temperature of the coldest months is 24.80 C. and the maximum of the warmest months is 33.20 C. (S ee

chart 1).

1Estudio Hidrolgico, Proyecto Hidroelctrico Cuesta de Piedra. Johnny A. Cuevas M2

idem.


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A A

26,81 27,59 28,42 28,46 27,62 26,96 26,86 26,98 26,75 26,59 26,56 26,76

26,00 26,30 27,00 27,20 26,80 26,30 26,10 25,80 25,60 25,50 24,80 25,00

28,30 29,10 30,00 30,30 29,00 28,10 28,50 32,00 31,20 31,50 32,00 33,20

20,00

22,00

24,00

26,00

28,00

30,00

32,00

34,00

Chart 1. Monthly Variation of the Temperatur - David Station

4.3 Wind

As for the variation of the wind, considering the David meteorological stations, which are located in the Chiriqui

River basin at 27 meters elevation, two behaviors are presented depending on the dry and rainy seasons (See

Chart 2).

With reference to Davids Station, the highest values of wind speed occur in the dry months when the region is

affected by the prevailing flow of the trade winds, recording a maximum speed of 3.30 m / s, whereas at the

beginning of the rainy season the wind speed decreases to a minimum value of 0.60 m / s.


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Figura 5

4.4 Relative Humidity

In terms of relative humidity, taking under consideration data from the David weather station, located in the

lower basin of Chiriqui River it can be noted that:

The average annual relative humidity is 78.54%. The lowest values occur in the dry season between Januaryand April. In February and March there were average records with an average of 57.75% in the rainy season.

The values undergo little variation throughout the Basin of the station. (See Chart 3).

A A

1,47 1,93 1,88 1,44 1,04 0,93 0,91 0,92 0,96 0,93 0,89 1,03

1,00 1,10 1,20 1,20 0,70 0,70 0,70 0,70 0,70 0,70 0,70 0,60

2,10 3,30 2,90 1,80 1,37 1,18 1,13 1,15 1,20 1,10 1,20 1,60

0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

Speedofwindinm/s

Chart 2. Wind speed at 2 m - David Station

A A

70,21 64,68 65,65 73,10 82,40 84,03 83,50 84,29 85,37 86,31 85,00 77,97

77,81 74,38 75,03 82,41 87,45 87,53 86,52 87,44 88,44 88,96 89,47 83,77

61,23 54,36 56,87 63,27 76,58 80,75 79,55 80,39 82,30 82,71 78,00 68,45

40,00

50,00

60,00

70,00

80,00

90,00

100,00

Chart 3. Monthly variation of the Relative Humidity in % - David station


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5. MORPHOLOGICAL CHARACTERISTICS

According to Dr. Joseph E. Villarreal IDIAP CIAC, the soil of the project area is located in the lowland area of

the Central Pacific and Western rich soils, as acrisols majority Nitisols, cambisoles with low fertility. This soilhas low depth.

They are characterized by vast plains and plateaus of degraded soils, with the presence of native grasses and

scrub forests. Most of these soils are composed of sedimentary rocks of marine origin and volcanic tuffs. The

topography is flat to slightly undulating, with weak to very weak slopes, although eroded residual reliefs

protrude in isolated form. The predominant areas of life in these areas are: tropical rain forest, wet forest and

tropical moist pre-mountainous forest.

5.1 Agrologic Capacity

According to the Agrological map of Panama, the project area is located at Category II. It is arable with some

limitations in the choice of plants. See Map 3.


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PROYECTO

Map 3. Agrology in the Chiriqui river basin.


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6. PRECIPITATION ANALYSIS

The determining factor in the seasonal distribution of rainfall throughout the Chiriqui river basin is constituted

by the annual migration of the Intertropical Convergence Zone.(ITCZ), which is the confluence of the trade

winds of both hemispheres, North and South. It is an area of light winds and variable convective unstable air

and strong development, with heavy rains.

The seasonal distribution of rainfall is controlled by the ITCZ , however, the totals occurring anywhere in the

country depend on factors such as elevation , topography , distance to the mountains , exposure to prevailing

winds , etc.

The pluviometric data used in the analysis of precipitation was obtained from the Department of

Hydrometeorology of Electric Transmission Company, Empresa de Transmisin Elctrica, S.A. ETESA. This

information is relevant to the Basin # 108, which denominates the Chiriqui River Basin. Stations used are:

Finca Lerida, El Valle, Caldera (Pueblo Nuevo), Potrerillo Arriba, La Cordillera, Los Palomos, Angostura de

Cochea, Veladero , Gualaca , Cermeo, Los Naranjos, Sombrero de Paja, David , Gualaca II. This analysis is

based on all the stations of the Basins and Sub-Basins adjacent to the Project.

Table 1. Precipitation measured at each station.

Station

NumberStation

Analyzed

Years

Station

Type

Elevation

(mamsl)

Average Annual

Rainfall (mm)

108-001 FINCA LRIDA 1975-2012 CC 1,700 2793.4

108-002 EL VALLE 1985-1998 CA 40 2687.3

108-004CALDERA

(PUEBLO NUEVO)1985-2012 CA 350 3835.5

108-006POTRERILLO

ARRIBA1975-2012 CM 930 3671.4

108-008 LA CORDILLERA 1985-2012 CM 1200 2757.3

108-009 LOS PALOMOS 1985-2012 CC 420 4337.7

108-013ANGOSTURA DE

COCHEA1985-2012 CM 210 3997.4

108-014 VELADERO GUALACA 1985-2012 CC 45 3388.3

108-015 CERMEO 1985-2012 CM 170 3266.1

108-017 LOS NARANJOS 1985-2012 BC 1200 2504.2

108-018 PAJA DE SOMBRERO 1985-2012 BC 388 3339.0

108-023 DAVID 1985-2012 AC 27 2610.3

108-043 GUALACA II 1996-2012 BC 100 4205.3


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AC: Type A Station ConventionalBC: Type B Station ConventionalCC: Type C ConventionalCA: Type C Automatic

CM: Telemetric

In general, the Chiriqui River basin records an average annual rainfall of 3337.9 mm. 92% of the rainfall

occurs between the months of May to December and the remaining 8% was recorded between January and

April. See Table 2.


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Table 2. Monthly rainfall in mm in the Stations at Chiriqui River Basin

STATION JAN FEB MAR APR MAY JUN JUL AGO SEP OCT

FINCA LERIDA 114.9 68.4 70.3 98.8 311.0 301.7 242.9 310.3 398.4 434.7 2

EL VALLE 36.2 13.9 66.8 102.8 341.3 371.4 297.9 340.0 346.7 443.2 2

CALDERA (PUEBLO NUEVO) 27.2 22.5 57.4 155.0 457.6 463.0 338.3 468.6 638.9 738.0 3

POTRERILLO ARRIBA 24.4 29.5 72.9 161.7 447.5 425.2 322.4 489.2 611.8 628.8 3

LA CORDILLERA 84.3 37.9 42.8 80.8 300.1 310.6 257.3 315.1 456.2 482.2 2

LOS PALOMOS 48.4 51.8 88.1 209.1 539.8 524.1 441.2 564.5 657.9 700.6 3

ANGOSTURA DE COCHEA 37.1 27.5 75.3 178.7 512.5 475.3 401.5 536.0 573.9 674.8 3

VELADERO GUALACA 32.8 33.6 62.5 152.5 400.3 412.2 396.2 462.2 465.2 503.8 3

CERMENO 36.8 28.2 62.2 142.7 409.6 396.5 339.1 433.1 473.1 509.7 3

LOS NARANJOS 65.1 31.2 47.3 84.6 276.1 317.2 233.2 326.4 390.9 416.9 2

PAJA DE SOMBRERO 18.7 18.4 56.7 131.0 423.5 418.1 265.8 386.3 561.3 661.7 3

DAVID 28.8 16.1 27.1 91.1 344.9 317.2 328.6 350.6 356.2 404.0 2

GUALACA II 36.2 40.2 69.2 184.5 528.4 478.9 447.8 585.5 598.0 663.9 4

Average 45.4 32.2 61.4 136.4 407.1 400.9 331.7 428.3 502.2 558.6

The station is located about David about 6.0 km. the project site


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6.1 Estimation of average annual rainfall

For the calculation of precipitation (mm) that a region or basin receives, the following methods are used:

Thiessen Polygons

Method isoyets

The Thiessen Polygon method allows distribution of precipitation according to the portion of the basin in the

study area that is influenced by each station. To construct the polygons, stations are connected by straight

lines and perpendicular lines are drawn to bisect the connecting lines to form polygons around each station.

The other method used to calculate the average annual rainfall is the method of isohyets, which represents

contours of equal rainfall intensity. It can be applied after verifying the consistency of the series of

meteorological data for the stations located within and near the Basin in study.

Taking into account data from the nearest stations to the project area and using them as a reference, a map of

Isohyets generated by the Electricity Transmission Company (ETESA) in Surface Water Balance for a period

from 1971 to 2002, isohyets on the basin under study were generated. With this analysis it was obtained that

the average rainfall in the area of the site is approximately 2.900 mm. (See Map 4)


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LEYENDA:

Estaciones Hidromtricas

Cuenca del ro Chiriqu

Isoyetas

Ros

Area del Proyecto

3000

Estaciones Pluviomtricas

Map 4. Isohyets in the Chiriqu river basin


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7. IDF CURVES

Precipitation, a variable of hydrological state can be characterized by the intensity, distribution in space and

time and frequency or probability of occurrence. For this it is necessary to have a large number of

observations extracted from pluviograph series, in order to define the pattern of behavior in a given area

and allow analysis or application. In this regard, the most widely used method is related to the intensity

curves Duration Frequency (IDF).

IDF curves are a graphical representation of the relationship between the intensity and a maximum

duration of rain event, associated with the frequency or period of return. For each return period there is adifferent curve (Nana, 2003; Pizarroet al, 2001). Tmez (1978), in turn, defines them as those curves that

result from joining the points representing the average intensity and different duration intervals all

corresponding to the same frequency or return period.

The IDF curves are one of the most useful tools for hydrologic design of maximum flows, when rainfall-

runoff models are used, such as the unitatian hydrographs or rational methods (Nana,2003). Thus, a large

number of water projects , such as designing outfeed flood , building bridges and construction of drainage

networks, among others, are defined in relation to the maximum precipitation might be expected for a given

period return.

The difficulty of Chiriqu river basin, on the one hand, is the small number of existing rainfall stations and on

the other the hand, the small number of reliable and suitable data appropriate for the creations of the IDF

curves.

For this study the rainfall IDF curves of station 108023 David (years 1971-1976) that were made by the

Department of Hydrometeorology of Electricity Transmission Company, ETESA, are presented. As

mentioned above, this station is the nearest to the project site.


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The Drainage Department of Studies and Designs, Ministry Of Public Works (MOP), recommends using the

following formulas of rainfall intensity I (mm/h) where Tc= Concentration time in hours:

Period of return of 10years

Period of return of 20 years




.


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8. CONCLUSIONS AND RESULTS

The results reported in this study have been supported by comprehensive and critical analysis, in such

a way to minimize any uncertainty in the results obtained.

Based on the Kppen classification, the project site is located between two climate zones: tropical

savanna climate Humid tropical climate.

The analysis results showed that the average precipitation on the Project Site is estimated at 2,900

mm per year.

The existing drainage system protecting the Interamerican Highway also prevents drainage runoff of

the exterior drainage basins from entering into the Study Area.

Idf curves most suitable for the Project Area are the ones made by ETESA using data from

meteorological station 108023 David.


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9. BIBLIOGRAPHY

Chow, Ven Te. Hidrologa Aplicada. McGraw-Hill INTERAMERICANA, S.A. Santaf de Bogota D.C..

Colombia 1994.

Cedeo, David B. Apuntes de Hidrologa. Universidad Tecnolgica de Panam, Facultad de Ingeniera

Civil, departamento de Hidrulica Sanitaria y Ciencias Ambientales, Panam, 1997.

Empresa de Transmisin Elctrica de Panam S.A., seccin de Hidrometeorologa Balance Hdrico

Superficial de Panam, Periodo 1971-2002. Panam 2008.

Gerencia de Hidrometrologa, ETESA.

Available in: http://www.hidromet.com.pa/

chiriqui hydrological-study old boundary

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