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

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 10 6 + 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. WATERSHEDOCTOBER 2007NOVEMBER 2007 282930311234 Angostura5.69.110.80.2 3.000 Chicoasén38.23.83.54.02.0000 Malpaso15381.8118.721.4104.53.64.52.2 Peñitas403.4308.9250.5100.3100.613.612.36.2 Ríos de la Sierra317.0249.6152.032.553.011.07.93.3 Mezcalapa263.9120.457.6105.127.10.310.09.5 Usumacinta47.140.959.01.310.14.95.80.8 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. The event: Flood succession Inflow hydrograph and Peñitas Dam free surface level evolution

11. 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 Oct. 11-12 Oct. 23-24 Oct. 28-30 MCL Water level MEL: 95.5 masl

12. 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

13. 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

14. 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

15. 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

16. 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.

17. 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

18. 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

19. 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

20. Thanks!