THE OCTOBER-NOVEMBER 2007 FLOODS IN TABASCO, MÉXICO: AN INTERIM DIAGNOSIS AND COURSES OF ACTION

2. THE OCTOBER-NOVEMBER 2007 FLOODS IN TABASCO, MÉXICO: AN INTERIM DIAGNOSIS AND COURSES OF ACTION Javier Aparicio, Polioptro F. Martínez-Austria, Alberto Güitrón, Aldo I. Ramírez Mexican Institute of Water Technology 4th International Symposium on Flood Defence: Managing Flood Risk, Reliability and Vulnerability Toronto, Ontario, Canada, May 6-8, 2008

3. Tabasco flatlands location

4. Gulf of Mexico Flatlands 40 km Tabasco Flatlands: October 2007 floods • Frequent flooding • Hernán Cortés • Mostly uncontrolled • October 28-30: 70% of Tabasco flatlands flooded Villahermosa Peñitas Dam De la Sierra Usumacinta Grijalva

5. Tabasco Flatlands: October 2007 floods • Villahermosa city: main affected town • 1 billion dollars in losses

6. Tabasco Flatlands: October 2007 floods • No human losses • 106 + people affected

7. The event: Antecedent precipitation • High antecedent precipitation • High moisture content • Critical levels in rivers prior to big flood October 23rd record

8. The event: Extreme event simultaneity Maximum precipitation (mm) recorded in the region Maximum values each day are shaded

9. The event: Evolution of levels in gauging stations NAMO = critical level

10. Oct. 11-12 Oct. 28-30 Oct. 23-24 Water level MCL Flood succession and Peñitas Dam operation • Angostura,Chicoasén, Malpaso retained runoff completely • Peñitas received flow from own watershed only • Precedent floods: Oct. 11-12, Oct. 23-24 • Operation was adequate MEL: 95.5 masl

11. The event: Forecast & alert system • Meteorological bulletins issued for general public • Lack of precise models for cold fronts and other meteorological phenomena • Deficient real-time alert systems • Insufficient investment in technology • Mandatory integral hydrometeorological system

12. Urban zones and vulnerability • Important city growth • Growth mainly along rivers margins • The urban growth plans are among the most important aspects to take into account to reduce the urban zones vulnerability. Urban growth 1975-2005

13. Hydraulic infrastructure for flood control I • 1999 floods: Integral Flood Control Program • Protection against floods in the Samaria, Carrizal, De la Sierra and Grijalva Rivers by means of levees and gates structures • Accelerate runoff into the ocean and protect urban centers

14. Hydraulic infrastructure for flood control II • Hydraulic infrastructure for flood control not completed • Lack of levees and control structures most probably favored flooding in the urban zone. Detour structure

15. Vulnerability and integral flood management I • Methodologies for integral flood control incorporating not only water resources management, but also the watershed, soil use, coastal zones and risk management. • Deforestation for wood exploitation, livestock pasture establishment and change to agriculture with primitive management which adds to urbanization in flooding zones. • Change in soil use from forest to agriculture→ severe scouring → great quantities of sediment→ reducing the rivers capacity and moistening and weakening of the rivers borders.

16. Vulnerability and integral flood management II • New studies: • Effects of deforestation in the rainfall-runoff relationship • Scour-sedimentation process • Territorial ordering and soil use. • Flood risk maps • Alert systems, forecast and monitoring networks

17. Courses of action I • Modern integrated flood management approach in order to prevent future disasters. • Revise joint operational policies of the existing infrastructure; establishment of a territorial ordinance plan

18. Courses of action II • Integral modeling system including hydrometeorological forecasting, rainfall-runoff relationships and dam operation: modernization of the monitoring system • Watershed conservation and management, social participation, training and spreading among the population and stakeholders

19. Thanks!