Estudio de Riesgo por Inundación para el Tramo de la Quebrada Medianía Comprendido entre la Calle 107B Sur con Carrera 9 Este y la Calle 111 Sur con Carrera 8 Este (Vía al Llano), en Bogotá D. C.

Abstract

This study evaluates flood hazard, vulnerability, and risk along the section of the Medianía Creek extending from 107B South Street at 9 East Avenue to 111 South Street at 8 East Avenue (Vía al Llano), in the locality of Usme, Bogotá, D.C., Colombia. Field visits revealed that this section of the creek is characterized by unplanned urban expansion, a high degree of soil impermeabilization, and the presence of buildings located in close proximity to the channel. In addition, according to reports from the local community, flood events have occurred in the area, particularly near Vía al Llano (8 East Avenue).

As a starting point, a photogrammetric drone survey was conducted to generate a Digital Terrain Model (DTM). Subsequently, the morphometric characterization of the watershed and the identification of land cover were carried out. Due to the lack of sufficient rainfall records, the Intensity-Duration-Frequency (IDF) curves developed by INGETEC (2015) for EAAB-ESP were adopted to derive the design hyetograph for a 100-year return period. Based on this information, hydrological modeling of the watershed was performed using HEC-HMS v4.12, applying the Soil Conservation Service (SCS) method to estimate abstractions and effective precipitation, together with the SCS Unit Hydrograph method to transform rainfall into runoff. Subsequently, two-dimensional hydraulic modeling was conducted using HEC-RAS v6.6 to estimate flood depths and flow velocities.

Based on the modeling results, the methodology proposed by IDIGER (2023) was applied to assess flood hazard, physical vulnerability, and flood risk at the building level. The results identified areas with moderate and high flood risk, primarily associated with their proximity to the floodplain and the unfavorable characteristics of existing buildings. Finally, conceptual measures are proposed to mitigate flood risk within the studied watershed.