Aplicación del SIG en la cartografía de riesgo por remoción en masa e inundación. Caso estudio cuenca Hanabanilla
Fecha
2014-07-08
Autores
Bueno Navarro, Iraida
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Editor
Universidad Central “Marta Abreu” de Las Villas
Resumen
La esencia de este trabajo es el diagnóstico, sobre una base cartográfica de escala media (1:25 000), de los eventos naturales de movimientos en masa (deslizamientos y desprendimientos de rocas) e inundaciones en el territorio objeto de estudio a través de un método indirecto de mapeo de amenazas, basado en un procedimiento de indexación. Para utilizar el método heurístico de amenaza de movimientos en masa en el área de estudio, se generó una amplia base de datos en ambiente de SIG, que contiene datos topográficos, geológicos, geomorfológicos, hidrológicos, textura de suelos y cobertura del terreno. La evaluación se hizo sobre la base de la construcción de un modelo matemático, que cuantifica el riesgo de los fenómenos de movimientos en masa e inundación; este modelo es una función lineal, que consiste de una serie de variables influyentes de forma relativa en las amenazas de movimientos en masa e inundaciones presentes en cada punto estudiado. La importancia de cada variable como factor determinante de la inestabilidad de laderas y la inundación se determinó cuantitativamente mediante la comparación por pares utilizando el así llamado Proceso de Jerarquías Analíticas (AHP por sus siglas en inglés). La integración de varios factores en un índice de amenaza único se logra mediante el procedimiento de suma lineal ponderada. Finalmente, se obtiene un mapa de riesgo mediante el cruce de los mapas de amenaza con los elementos vulnerables de centros poblacionales e infraestructura, localizados próximo a las orillas de los ríos o al pie de las laderas.
La propuesta metodológica se aplicó en la cuenca hidrográfica Hanabanilla, localizada en la pendiente norte del Macizo Guamuhaya, provincias de Villa Clara y Cienfuegos. Esta cuenca es un área de relieve montañoso con pendientes promedios de 25-30° y de topografía de ondulada a alomada con pendientes predominantes de 5 a 15°. Según registros pluviométricos, en julio del 2005 se obtuvieron registros de hasta 572 mm en 24 horas en la estación pluviométrica “Guanayara”. Tales precipitaciones fueron las que se tomaron como factor detonante de procesos de movimientos en masa e inundaciones.
This paper focuses on the diagnosis of the natural events of mass movements (landslides and rock falls) and floods in the territory object of study by means of an indirect hazard mapping index-based approach. In order to utilize the heuristic landslide hazard approaches in the study area, an extensive GIS database was generated containing topographical, geological, geomorphological, hydrologic, soil texture and vegetative cover data. The evaluation was realized in base of the construction of a mathematical model which quantifies the risk of a mass movement and flood; this model is a linear function, which consists of a series of variables that influence, in relative form the mass movements and flood hazards presented by each point. The relative importance of each variable as a determining factor of slope instability and flood was quantitatively determined by pairwise comparison using the so-called analytical hierarchy process (AHP). The integration of the various factors in a single hazard index was accomplished by a procedure based on their weighted linear sum. Finally, trough the crossing of de hazard maps with the vulnerable population centers and infrastructure, localized near to river banks or in the foot of hillsides, a risk map is obtained. The study is carried out in the hydrographic basin Hanabanilla, located in north slope of the Macizo Guamuhaya, provinces of Villa Clara and Cienfuegos. Its mountain land surface has an average slope angle between 25 and 30°. The rainfall in the region has a strong relief control. According to the rainfall records, it was maximal values as many as 572 millimeters in “Guanayara” rainfall station in July of 2005. Such rainfall was used as a triggering factor for generation and/or reactivation of mass movement.
This paper focuses on the diagnosis of the natural events of mass movements (landslides and rock falls) and floods in the territory object of study by means of an indirect hazard mapping index-based approach. In order to utilize the heuristic landslide hazard approaches in the study area, an extensive GIS database was generated containing topographical, geological, geomorphological, hydrologic, soil texture and vegetative cover data. The evaluation was realized in base of the construction of a mathematical model which quantifies the risk of a mass movement and flood; this model is a linear function, which consists of a series of variables that influence, in relative form the mass movements and flood hazards presented by each point. The relative importance of each variable as a determining factor of slope instability and flood was quantitatively determined by pairwise comparison using the so-called analytical hierarchy process (AHP). The integration of the various factors in a single hazard index was accomplished by a procedure based on their weighted linear sum. Finally, trough the crossing of de hazard maps with the vulnerable population centers and infrastructure, localized near to river banks or in the foot of hillsides, a risk map is obtained. The study is carried out in the hydrographic basin Hanabanilla, located in north slope of the Macizo Guamuhaya, provinces of Villa Clara and Cienfuegos. Its mountain land surface has an average slope angle between 25 and 30°. The rainfall in the region has a strong relief control. According to the rainfall records, it was maximal values as many as 572 millimeters in “Guanayara” rainfall station in July of 2005. Such rainfall was used as a triggering factor for generation and/or reactivation of mass movement.
Descripción
Palabras clave
Mapas de Susceptibilidad, Amenaza, Vulnerabilidad y Riesgo, Movimientos en Masa, Método de Jerarquías Analíticas, Sistema de Información Geográfica, Cuenca Hidrográfica Hanabanilla, Hydrographic Basin Hanabanilla, Geographical Information System, Analytical Hierarchy Process, Vulnerability and Risk Maps