FRAGILIDAD, VULNERABILIDAD Y RIESGO EN LA CUENCA BAJA DEL SISTEMA GRIJALVA–USUMACINTA

Abstract

The state of Tabasco with a surface of 24.277 km2, comprising 17 municipalities and a population of nearly two million people, holds 30% of the country's water and 60% of its surface is water, for morphological conditions , climate and great nature alluvial delta, results in an intricate network of rivers in the mouth of the Frontera bar, two rivers converge in the country, the Grijalva and Usumacinta, these rivers and their tributaries descend from the mountainous region of Chiapas with a large flow rate is increased downstream in the plain of Tabasco by the heavy rains that become an annual average greater than 2500 mm, developing a series of rambling and bifurcated channels that give rise to numerous swamps and ponds to which some authors designated as the Delta of Tabasco while the cumulative average in Mexico is 771.8 mm from 1941 to 2000. Tabasco remained isolated for centuries the country by the lack of roads, at the beginning of the last century began the extensive exploitation of its resources primarily to the disappearance of tropical forests, to promote agriculture and ranching, in the seventies then exploiting the rich discovered oil fields and promoting the petrochemical industry, this intensive exploitation regardless of land use and urban, which would led to chaotic growth of cities as Villahermosa, Cárdenas, Huimanguillo, Macuspana, among others, leading to the occupation of the easily flooded lowlands that given the regular presence of the avenues that exceed the carrying capacity of rivers, such as in the plain area with rivers Samaria, Carrizal, Mezcalapa, Grijalva and Usumacinta, causing severe damage to infrastructure and loss of life. Environmental degradation is a product of human activity which has resulted in major changes in the lower basin of the Grijalva-Usumacinta system, these changes can be quantified through environmental indicators. This paper proposes a methodology for using indicators allows for a better diagnosis of the watershed that can serve as a basis for making decisions concerning the conservation and utilization of natural resources.