The 2007 flood in Tabasco, Mexico: an integral analysis of a devastating phenomenon

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The 2007 flood in Tabasco, Mexico: an integral analysis of a devastatingphenomenonFabian Rivera-Trejoa; Gabriel Soto-Cortésb; Baldemar Méndez-Antoniob

a Juarez Autonomous University of Tabasco, Tabasco, México b Metropolitan Autonomous University,Azcapotzalco, México

First published on: 15 September 2010

To cite this Article Rivera-Trejo, Fabian , Soto-Cortés, Gabriel and Méndez-Antonio, Baldemar(2010) 'The 2007 flood inTabasco, Mexico: an integral analysis of a devastating phenomenon', International Journal of River Basin Management,,First published on: 15 September 2010 (iFirst)To link to this Article: DOI: 10.1080/15715124.2010.508746URL: http://dx.doi.org/10.1080/15715124.2010.508746

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Research paper

The 2007 flood in Tabasco, Mexico: an integral analysis of a devastatingphenomenon

FABIAN RIVERA-TREJO, Professor of Hydraulic Engineering, Juarez Autonomous University of Tabasco.Cunduacan, Tabasco, Mexico. Email: [email protected] (Author for correspondence)

GABRIEL SOTO-CORTES, Professor of Civil Engineering, Metropolitan Autonomous University, Azcapotzalco,Mexico. Email: [email protected]

BALDEMAR MENDEZ-ANTONIO, Professor of Civil Engineering, Metropolitan Autonomous University,Azcapotzalco, Mexico. Email: [email protected]

ABSTRACTA markedly intense rain fell on southeastern Mexico during the period of 29 October–1 November 2007. As a result, the state of Tabasco recorded thegravest flood in the last 50 years. A reconstruction of the event is presented, including the identification of the factors that aggravated the sequels, and adiscussion of the actions that were carried out to evaluate the flooding. The phenomenon consisted of a succession of rains in the region, including 3 daysof continuous rain with over 403 mm d21. The operation of a system of dams, the saturation of the soil, and runoff times below 16 h were the factors thatgenerated the catastrophe, in synergy with the meteorological phenomenon. The analysis presented here will aid in understanding the development ofthe phenomenon in an integral way, and in establishing the minimum procedures to be followed to evaluate similar events in other regions where, as inMexico, one does not have timely access to information. In the case of this disaster, for example, different versions of the causes of the flood continued tocirculate 6 months after it took place, some lacking technical bases and some access-restricted. However, the information generated provided the aca-demic community and state officials with a reference on which to evaluate the event. This analysis also makes a contribution by placing emphasis on theneed to establish non-structural mitigation measures such as future urban growth and regulation plans and future early warning systems against flooding,monitoring the variables that were analysed and generating products useful to the decision-makers involved in civil protection systems and in carryingout preventive measures to mitigate the effects of extreme events.

Keywords: Rainfall; extreme events; effects; risks; protection plans

1 Introduction

The state of Tabasco suffered its gravest flood of the last 50 years

during the year 2007. An intense rain fell on southeastern Mexico

from 29 October to 1 November, and mainly affected the states of

Chiapas and Tabasco (Figures 1 and 2). The heavy rain followed

the combination of a cold front from the USA and tropical storm

‘Noel’ (Hernandez Unzon 2007). The result was 4 days of rain

that recorded the equivalent of 1 year’s rain in Tabasco

(CONAGUA 2007). The overflowing of rivers and streams

caused one of the greatest floods in the country, although fortu-

nately there were no human losses. As a result of its geographic

position, the history of Tabasco has documented a great number

of floods (Velazquez 2001). Floods are extreme natural events

that have occurred in diverse regions of the world including

Italy (Ratto et al. 2007), India (Shankar 2005), the Netherlands

(De Witt et al. 2007), England (Marsh and Hannaford 2007)

and the USA (Biloxi 2008), together with the resulting problems.

Ganoulis (2003) commented that floods are infrequent natural

phenomena, with extreme rains as the main cause. At the same

time, the effect is maximized by anthropogenic activities and

hydraulic constructions that alter the natural conditions of

runoff patterns and ecosystems in general. The flood of 2007

severely damaged the infrastructure established in the state of

Tabasco. Damage was reported in highways, urban areas, electric

networks, educational buildings, hydraulic installations and the

media, among others (SAOP 2008). To date, although there are

a variety of versions on the causes that originated the flood,

several lack technical support or are access-restricted. The objec-

tives of this study were to describe the 2007 event, to analyse

Received 6 October 2009. Accepted 13 July 2010.

ISSN 1571-5124 print/ISSN 1814-2060 onlineDOI:10.1080/15715124.2010.508746http://www.informaworld.com

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some of the actions that were implemented after the event to

mitigate future risks, and to discuss the need to install an early

warning system. This analysis will make it possible to identify

the causes and/or factors that originated this phenomenon and

to help evaluate the system for the protection against future poten-

tial flooding, considering that the data and information on the

event were provided after it took place – a posteriori (diagnosis).

The reason behind this is that there is no entity in Tabasco, or in

Mexico, in charge of real-time monitoring of this type of event.

Phenomena such as those described here need to be monitored,

with forecasting and operational objectives, in order to generate

useful hydrometeorological products that decision-makers may

use to mitigate future damage caused by extreme events of this

type in areas like Tabasco, where flooding is extreme and frequent

and economic losses are considerable. CENAPRED (2009)

reported a loss of 3100 million dollars for this flood. Also,

Mexico has no urban growth and regulation plans that consider

areas prone to flooding.

2 Location

The state of Tabasco is located in southeastern Mexico, in the

physiographic province of the Coastal Plain of the Southern

Gulf of Mexico (Figure 3). It covers an area of approximately

24,661 km2, equivalent to 1.3% of the national territory (Velazquez

1994). The average annual rainfall (recorded from 1941 to 2005)

is the highest in the country at 2405 mm (CONAGUA 2006).

3 Method

The processing and analysis of the information was based on the

hydrometric, climate and dam data published daily by the Comi-

sion Nacional del Agua (CONAGUA – National Water Com-

mission) at its office for the Frontera Sur basin. The region that

was affected harbours the data recording network located in

the basins of the High Grijalva, Low Grijalva and Usumacinta.

The phenomenon was described by separating it into its climato-

logical, pluviometric, hydrometric and dam operation com-

ponents. Tides were not included in the analysis as there was

no access to the official data. Each element was considered indi-

vidually, and was later integrated, to allow a better comprehen-

sion of the event. The meteorological analysis was carried out

using the information contained in a description of cold front

No. 4 prepared by the National Water Commission in 2007 (Her-

nandez Unzon 2007). This event was described chronologically

from the moment it was predicted to its conclusion. The pluvio-

metric analysis consisted of constructing rain hyetographs for

some stations, based on the rainfall data presented in the official

Figure 2 Gaviotas neighbourhood, Villahermosa, Tabasco

Figure 1 Downtown Villahermosa, Tabasco

2 Fabian Rivera-Trejo et al.


bulletins of the CONAGUA (2007). The period that was ana-

lysed spanned from 1 October to 3 November 2007. The stations

that were selected were those that recorded more than 50 mm of

rain, considering that these contributed the most during the

event. All hyetographs were grouped in one figure in order to

identify periods of intense rains.

The hydrometric analysis was centred in the city of Villaher-

mosa, the capital of the state, which suffered the gravest conse-

quences of the overflowing of the rivers that surround it. The

hydrometric stations included in the analysis are shown in

Figure 4, and their critical levels (CL) are presented in Table 1.

CLs are defined by the CONAGUA as the overflow river levels,

and are referenced in metres above medium sea level (masl).

Figures were prepared to represent the level of the rivers

during the period from 1 October to 3 November 2007 using

the information contained in the CONAGUA records.

The importance of the dam system (four dams) lies in its location

throughout the High Grijalva, and in the fact that it is the most

important hydroelectric complex in Mexico. Overall, it generates

approximately 40% of the hydroelectric energy of the country.

The system discharges its water into the Low Grijalva, and for

this reason, it has a significant effect on the coastal plain of Tabasco.

Figure 5 shows the effect of the dams on the control of runoff

to the Low Grijalva. The operation of the dam system during the

2007 event is considered a key point in its development, as the

workings of the dams delayed the response time of the hydrolo-

gical system and, according to official reports, this resulted in no

loss of human lives.

The dam system in the High Grijalva dates from 1964, the

year when the construction of the Malpaso Dam was concluded.

The purpose of this dam is to regulate runoff. A runoff greater

than 8000 m3s21 was recorded in 1963. In 1696, 1970 and

1973, the chutes were put into operation before the Angostura

Dam was finished in 1975. This dam has the greatest storage

capacity of the system. The Chicoasen Dam has the greatest

installed capacity, although its regulating capacity is limited,

and it started working in 1980 to generate energy. Finally, in

1987, the last of the dams built on the High Grijalva, the

Penitas Dam, started working with a small regulating capacity

in comparison with the Angostura and Malpaso dams.

The principal characteristics of the dam system are shown in

Table 2, and Figure 6 presents the layout of the dams. The operation

of the dams was obtained from plotting the data recorded for the

open surface water levels and the flow release that took place.

4 Results

At the time of this study, the information related to the hydrome-

teorological phenomena that caused this flood was not concen-

trated in one place and there was no clarity as to its origin. For

example, it was said that the main cause was an inadequate func-

tioning of the dams. The individual analysis of the phenomena

and its ‘integration’ carried out in this paper makes it possible

to understand the phenomenon globally and to propose mitiga-

tion measures for future flood risks.

5 Meteorological

The meteorological event of October 2007 started on Thursday 18

October when cold front No. 4, associated with an air mass

Figure 3 State of Tabasco, Mexico

2007 flood in Tabasco, Mexico 3


travelling over most of the USA, was predicted three days in

advance as a long-lasting event with very strong and intense

rains throughout the Gulf of Mexico, the southeastern region of

the country and the Yucatan peninsula. The cold front originated

in a low pressure area over the Great Lakes, USA, on 22 October,

entered northern Mexico, moved over Nuevo Leon and Tamauli-

pas, and proceeded towards southeastern Mexico. It extended

from the low pressure area over eastern USA to Belize on 24

October, and presented a nucleus of high pressure with strong

and isolated rains over Chiapas and Tabasco. Later, it moved

towards the Yucatan peninsula together with an unstable area. It

then combined with tropical storm ‘Noel’, 130 km east-southeast

of Cuba, and returned over Yucatan to the Campeche Sound,

Tabasco and Chiapas. From 26 to 30 October, the cold front

remained stationary over the Gulf of Mexico; its convection

potential increased and strong rains began to fall during this

period on the tropical forest of Chiapas and the Sierra of Tabasco,

with maximum daily values of 200–300 mm (Figure 7). The

rains decreased significantly on 1 November, passing from

moderate to light, and the extreme event concluded. However,

the effects and water runoff continued.

6 Pluviometric analysis

A summary of the rains recorded from 26 October to 3 November

is presented in Table 3, together with the accumulated rain values

Figure 4 Rivers, dams and hydrometric stations, along the High and Low Grijalva

Table 1 Hydrometric stations

No. Station CL (masl)

52 Platanar 32.28

55 Samaria 14.90

57 Gonzalez 8.77

35 Oxolotan 39.53

36 Tapijulapa 24.63

38 Puyacatengo 29.65

37 Teapa 37.71

43 Pueblo Nuevo 7.49

40 San Joaquın 23.12

44 Gaviotas 5.42

45 Muelle 5.24

46 Porvenir 4.74

68 Salto de Agua 10.99

69 Macuspana 9.45

59 Boca del Cerro 18.65

63 San Pedro 9.01



(Table 4). The average rainfall for the month of October in the

state of Tabasco is 317.5 mm (CONAGUA 2008). Thus, the

rain that fell in one day during the October event was greater

than the average for this month in this region.

In the case of the accumulated rainfall for the same period,

1074 mm were recorded at the pluviometric station of Ocotepec,

and this represents almost half of the average annual rainfall

(2405 mm) recorded for the state of Tabasco for the period of

1941–2005 (CONAGUA 2006).

Figure 8 presents the succession of rains that fell on the High

and Low Grijalva from 1 October to 3 November and its relation-

ship with the meteorological phenomena (cold fronts) that hit the

region. The first event occurred on 9–13 October and was associ-

ated with cold front No. 2 (CF2), the second spanned from 17 to

18 October and was associated with cold front No. 3 (CF3), cold

front No. 4 (CF4) arrived after 24–25 October, and the last of the

heavy rains occurred from 29 October to 1 November when

stationary cold front No. 4 (SCF4) arrived. This succession of

rains saturated the soil in a short time and, together with a

deficient drainage system, caused water levels to rise and

streams and rivers to overflow.

7 Hydrometric analysis

Plots were constructed with the information contained in the

hydrometric reports, and show the levels of the rivers before,

during and after the event. These levels were recorded at

the hydrometric stations that are located in the region of the

coastal plain that was directly affected by the flooding of the

city of Villahermosa. Figure 9(a) and (b) shows the rivers in

the watershed of the Sierra that are not regulated, and their over-

flowing or CL as defined by the CONAGUA: Oxolotan (CL ¼

39.53 masl), Teapa (CL ¼ 37.71 masl), Tapijulapa (CL ¼

24.63 masl) and Pichucalco (hydrometric station San Joaquın,

CL ¼ 23.12 masl). These mountain rivers meet downstream

and form what is known as the river of the Sierra. They

reached their CLs on 12 October following the intense rains

Figure 5 Effects of the dam system on flood regulation (Low Grijalva)

Table 2 Characteristics of the dam system

Dam Angostura Chicoasen Malpaso Penitas

Maximum extraordinary water level (MEWL) (masl) 539.50 395.00 188.00 93.50

Maximum ordinary water level (MOWL) (masl) 533.00 392.00 182.50 87.40

Minimum ordinary water level (MINOWL) (masl) 500.00 380.00 144.00 85.00

Top of the gate (masl) 538.60 394.00 183.50 91.13

Crest of spillway (masl) 519.60 373.00 167.60 76.50

Total capacity (106m3) 19,736.00 1443.00 14,058.00 1485.00

Conservation capacity (106m3) 15,548.00 1372.83 12,373.00 1091.00

Minimum capacity (106m3) 2379.50 1168.81 3055.73 960.99

Source: CONAGUA 2007



generated by cold front No. 2. Later, the Pichucalco river reached

and once again overpassed its CL on 24 October follwing cold

front No. 4, while the Teapa and Tapijulapa rivers remained at

lower levels during the same period. These two rivers presented

a new peak on 29 October when cold front No. 4 returned. This

also caused an increase in levels in the Pichucalco river on

1 November.

The Platanar river that runs freely (Figure 9(c)) and is a branch

of the Mezcalapa river presented several peaks that reached its

CL (CL ¼ 32.28 masl) on 12–14, 17, 20 and 24–27 October,

as well as an extraordinary increase from 29 October to

6 November. Figure 9(d) shows that the water at the station on

the Samaria river rose above its CL (CL ¼ 14.20 masl) from

30 October to 4 November. It is important to point out that the

water in this river drains practically into the sea; for this

reason, an improvement in its drainage may contribute to

decrease the risk of flooding in the Low Grijalva. The water in

the Carrizal river (hydrometric station Gonzalez) above the

city of Villahermosa rose above its CL (CL ¼ 8.77 masl) on

29 October and 5 November. The hydrometric stations located

around the city of Villahermosa include: (1) the Gaviotas

station located upriver from the city where the water rose

Figure 7 Infrared image. Increased convection potential on Chiapas and TabascoSource: Hernandez Unzon 2007

Figure 6 Dam system along the High Grijalva



above its CL (CL ¼ 5.42 masl) from 14 October to 16 Novem-

ber, (2) the Muelle station at the city broadwalk (5.24 masl)

where the water rose above its CL from 24 October to 14 Novem-

ber and (3) the Porvenir station downriver that reached its CL

(CL ¼ 4.74 masl) on 24 October and remained there until 14

November (Figure 9(e)).

8 The workings of the dam system

Plots were constructed using the information contained in the

CONAGUA reports, to represent the operation of the dams that

constitute the hydroelectric system of the Low Grijalva. The

period considered was 1 October–3 November 2007. The

elevation of the open surface water was plotted on the left side

of the vertical axis, and its discharge was plotted on the right

side. The operation of the dam system during October was the

following (CONAGUA reports). The Angostura hydroelectric

plant, which has the greatest storage capacity of 19,736 Mm3,

maintained a turbine operated flow release from 1 to 24 October.

It then stopped the flow release operations until 27 October

when it renewed operations, although at a lower scale, after

which it again stopped operations on 31 October (Figure 10(a)).

The level of the water body during the study period remained

Table 3 Rainfall

Location Station

Rainfall (mm)

October 2007 November 2007

26 27 28 29 30 31 1 2 3

21 Santa Maria 0.0 0.0 0.0 153.0 81.8 18.7 21.4 15.4 0.8

25 C.H. Malpaso 0.0 0.0 1.3 85.3 39.8 16.0 51.4 15.5 3.6

27 Ocotepec 0.0 0.0 1.0 403.4 308.9 250.5 0.0 110.6 0.0

28 Romulo Calzada 0.0 0.0 0.0 160.4 107.2 41.4 94.9 13.9 12.4

35.5 Sayula 0.0 0.0 0.0 294.4 177.8 131.9 100.3 51.2 6.7

30 C.H. Penitas 0.2 0.0 0.3 217.6 149.5 32.5 90.2 11.5 13.6

51 Plan de Ayala 0.0 0.0 0.2 240.0 120.4 34.0 83.0 8.4 0.3

52 Platanar 0.3 0.0 1.4 192.2 107.1 26.7 105.1 12.6 0.0

54 Cardenas 0.0 0.0 0.0 176.0 120.0 20.0 86.0 0.0 0.0

55 Samaria 0.0 0.0 0.0 263.9 86.0 29.4 63.4 13.8 0.0

57 Gonzalez 0.0 0.0 0.0 105.9 197.4 57.6 53.5 27.1 0.0

68 Salto de Agua 0.0 0.0 0.0 77.9 44.5 6.2 0.3 3.7 14.6

69 Macuspana 0.0 0.0 0.0 124.7 94.0 76.0 0.0 11.5 14.2

Table 4 Accumulated rainfall

Location Station

Accumulated rainfall (mm)

October 2007 November 2007

26 27 28 29 30 31 1 2 3

21 Santa Maria 0.0 0.0 0.0 153.0 234.8 253.5 274.9 290.3 291.1

25 C.H. Malpaso 0.0 0.0 1.3 86.6 126.4 142.4 193.8 209.3 212.9

27 Ocotepec 0.0 0.0 1.0 404.4 713.3 963.8 963.8 1074.4 1074.4

28 Romulo Calzada 0.0 0.0 0.0 160.4 267.6 309.0 403.9 417.8 430.2

35.5 Sayula 0.0 0.0 0.0 294.4 472.2 604.1 704.4 755.6 762.3

30 C.H. Penitas 0.2 0.2 0.5 218.1 367.6 400.1 490.3 501.8 515.4

51 Plan de Ayala 0.0 0.0 0.2 240.2 360.6 394.6 477.6 486.0 486.3

52 Platanar 0.3 0.3 1.7 193.9 301.0 327.7 432.8 445.4 445.4

54 Cardenas 0.0 0.0 0.0 176.0 296.0 316.0 402.0 402.0 402.0

55 Samaria 0.0 0.0 0.0 263.9 349.9 379.3 442.7 456.5 456.5

57 Gonzalez 0.0 0.0 0.0 105.9 303.3 360.9 414.4 441.5 441.5

68 Salto de Agua 0.0 0.0 0.0 77.9 122.4 128.6 128.9 132.6 147.2

69 Macuspana 0.0 0.0 0.0 124.7 218.7 294.7 294.7 306.2 320.4



always below the maximum ordinary water level (MOWL ¼

533 masl). The Chicoasen hydroelectric plant, which has the

greatest installed capacity but practically no storage capacity at

1443 Mm3, operated continuously throughout the month (Figure

10(b)). It can be seen that the level of this water body is very

sensitive to flow release, mainly as a result of its size, and this

dam had no influence on the development of the event. The

Malpaso hydroelectric plant, with a capacity of 14,058 Mm3,

operated non-stop from 1 to 12 October, after which it stopped

flow release operations. It then renewed operations, although

at a reduced rate, from 16 to 18 October and from 21 to 24

October, after which, from 24 October onwards, it remained com-

pletely inactive (Figure 10(c)). This decision permitted a better

management of the Penitas Dam located downstream, which suf-

fered the flooding of its own basin only. The level of the water

body increased throughout October, although on 3 November it

was still below its MOWL (182.50 masl). Finally, the Penitas

hydroelectric plant (Figure 10(d)) operated until 11 October in

such a way that the level of the water body was very close to the

minimum operating water level (MINOWL ¼ 85 masl). On 12

October, a significant increase in water level was observed, at

88.48 masl over the MOWL. For this reason, turbine operations

increased that day to an average of 720 m3s21 and remained so

until 18 October. On 20 October, the water body returned to a

level very near the MINOWL (84.94 masl). A new increase in

water level was observed on 23 October and a maximum level

was recorded on 26 October (89.08 msnm). Turbine operations

then increased by 500 m3s21 and the water level decreased. On

28 October, the level again increased rapidly up to 91.30 masl

and flow release operations started on 29 October, both turbine

operated and with the use of chutes, with flow release values up

to 2025 m3s21. This brought the peak down to the safe level of

88.46 masl on 3 November, when the chutes stopped operating.

9 Integral description of the phenomenon

The phenomena were analysed individually in the previous

section. In this section, an integral analysis of the phenomena

is presented to help better understand the event that took place

in Tabasco in 2007.

A particularly severe phenomenon took place from 29

October to 1 November 2007, in response to the conjunction

of the following factors: periods of successive rains that

became stationary over the region throughout the month, very

intense rains particularly from 29 October to 1 November, soil

that was saturated and partly saturated by the rains of the pre-

vious days, the rivers of the Sierra were near their CLs since

12 October, an extraordinary input of water to the Penitas Dam

during the three periods of 12 to 16, 24 to 28 and 29 to 31

October, the increase in water level of the Platanar river on 12

to 14, 17, 20 and 24 to 27 October and an extraordinary increase

from 29 October to 6 November, and the operation of chutes to

let out excess water from the Penitas Dam starting on 29

October. The co-occurrence of these factors caused the centre

of the city of Villahermosa to lie under water from 29 October

to 9 November 2007.

Reconstructing the event, a strong runoff associated with

very intense rains occurred with little influence from the high

reaches of the Grijalva. The Malpaso hydroelectric plant

remained inactive from 24 October onwards, retaining water

from the higher areas. For this reason, the increase in the

water level in the Penitas hydroelectric plant was mainly due

to runoff from its own basin. Two effects acted together

between 28 October and 2 November: on the one hand

runoff originated by the rivers of the Sierra was strong, and

on the other the Penitas Dam filled very quickly and then

released its water. These factors, together with the area of

Figure 8 Rainfall periods from 1 October to 3 November 2007



affected land and the estimated losses that include 1,487,000

people affected (74% of the population), 1,526,601 flooded

hectares (62% of the land), 1456 affected localities (58% of

localities), 3505 schools (66% of schools), road and hydraulic

infrastructure, with an approximate cost of 1542 million

pesos (SAOP 2008), turned this event into one of the most

catastrophic nationally and worldwide.

A useful measure to prevent and mitigate flood damage is

the identification of areas prone to flooding. However, in the

particular case of Villahermosa, Tabasco, the city is located in

Figure 9 Water levels recorded by the hydrometic stations



an extremely flat down-river area of the river basin (Figure 11)

that makes it impossible to identify clearly defined flooding

areas. Thus, the proposal generated by the diagnosis of the

event aimed to define areas at risk, based on hydrologically

correct digital elevation models with enough vertical resolution

to estimate flooding areas, such as the LIDAR system.

After the 2007 event and considering the difficulty to quanti-

tatively define risk areas of flooding based on peak discharges,

the Villahermosa guildhall (Galindo-Alcantara et al. 2009) pre-

pared a qualitative flood risk map, including a colour classifi-

cation of risk areas according to the degree of danger. For the

centre of Villahermosa, high danger areas are red, medium

danger areas are yellow and low danger areas are green (Figure

12). A digital model of the ground was consulted to establish

the risk gradient and prepare the map. The three danger levels

were based on the possible increase in volume in the water

bodies. The basic information is now available and may be

used to design future urban growth and regulation plans and gen-

erate strategies for the prevention of disasters and the reduction

of risks. Up to now, these plans had not considered flooding

risk areas for Mexico.

10 Future risk mitigation measures

The Proyecto Integral Contra Inundaciones (Rubio and Triana

2006) designed a proposal to control the river system of the

Low Grijalva (Berezowsky et al. 2003, Gracia-Sanches et al.2003) after the flood of the year 1999. The plan intended to

control three subsystems: Mezcalapa-Samaria (Figure 13(a)),

Carrizal-Medellın (Figure 13(b)) and the rivers of the Sierra

(Figure 13(c)). The objective was to protect urban, agricultural

and cattle areas, as well as infrastructure, against floods. It

specified four points: to install structures for the regulation

of excess flow, to maintain a conservative flow, to periodically

remove and dredge materials to improve the drainage of the

system, and to allow an increase in the water level up to a

safe range with the use of levees. At the time of the flood,

Figure 10 The workings of the dam system: (a) Angostura, (b) Chicoasen, (c) Malpaso, (d) Penitas



the system had not been completed, lacked the construction

of control structures and a number of protection levees had

not been finished. After the events of October 2007, a re-eva-

luation of these points was proposed, including the design and

adaptation, implementation or modification of some of the

proposed actions. In addition, despite having worked on

ample projects for the prevention of floods and the mitigation

of risks, to date there are not measures of prevention or means

Figure 11 Sub-basins and location of the Angostura, Chicoasen, Malpaso and Penitas dams in the High Grijalva and the plain in the Low Grijalva

Figure 12 Flood risk map for the centre of Villahermosa, Tabasco



to warn the population. Added to this, the scarcity of integral

hydraulic programmes in past years has led to the poorly

planned construction of dikes, roads and highways that

blocked the free flow of water to the lagoons and the sea, gen-

erating a slow drainage and a considerable accumulation of

water, and causing water levels to rise and rivers to overflow.

11 Conclusion

It is obvious that the actions taken by the State to prevent floods

have not had the desired effect, as was proven by the 2007 flood.

Following the diagnosis of the flood event, it was found that a

great number of proposed actions are of the structural type,

and that non-structural measures and actions have practically

not been considered as part of the solution. These non-structural

measures include the individual observation and monitoring of

the analysed phenomena, and the integration in a single model

capable of generating a warning system useful both to the auth-

orities and to the population in general. In the case of Tabasco,

the flat surface makes it impossible to relate flooding areas to

peak discharges. Moreover, the variability of the meander

rivers makes it very difficult to establish peak discharges.

Thus, a warning system and future urban growth and regulation

plans (non-structural measures) for regions with plains as that

described needs to include flood risk areas in colours rather

than numeric, for example, yellow for low risk, orange for

medium risk and red for high risk areas.

The need to develop a warning system that includes hydro-

logical and meteorological forecasting, risk thresholds for the

water level at the hydrometric stations, pluviographs and

dams, as well as the recording of rainfall data by radars and

meteorological satellites (not applied in Mexico at present) is

emphasized in this study. This should all be integrated in an

Early Warning System against flooding, through which data

on extreme events may be monitored, stored, processed and

analysed, and input to the hydrological, climatic and meteoro-

logical models, in order to satisfy operational and forecasting

purposes that will increase the time of response when an

event occurs. Instruments need to be bought, including meteor-

ological radars, satellite images and automatic hydrometric and

surface stations, to measure and monitor convective systems,

rainfall fields, and river and basin levels that, together with

structural measures, will allow the construction of an effective

system for the protection and mitigation of flooding, that will in

turn reduce to a maximum the effects of events such as that of

Tabasco in 2007.

Acknowledgements

The authors express their thanks to the State Government of

Tabasco through its Secretarıa de Asentamientos y Obras

Publicas (Public Works Secretary) for the help provided and

for allowing access to information, and to Arq. Leticia Estrada

for collaborating in data and image processing.

Notation

CL ¼ critical level (masl)

MEWL ¼ maximum extraordinary water level (masl)

MOWL ¼ maximum ordinary water level (masl)

MINOWL ¼ minimum ordinary water level (masl)

Figure 13 Risk mitigation subsystems: (a) Mezcalapa-Samaria, (b) Carrizal-Medellin, (c) de la Sierra



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http://smn.cna.gob.mx/productos/map-lluv/precipit.gif

http://200.23.34.73/

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The 2007 flood in Tabasco, Mexico: an integral analysis of a devastating phenomenon

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