Maestría en Ingeniería Ambiental · 2026

Effects of climate change and urban expansion on flood regimes in the Aburrá–Medellín river basin

Resumen

Climate change and rapid urban expansion are reshaping the hydrological response of mountainous tropical cities. In the Aburrá Valley (Colombia), these processes interact within a steep, densely urbanized watershed that is highly sensitive to extreme rainfall. This study quantifies how projected increases in precipitation intensity and mid-century land-use transformations may alter flood peaks across the basin. The analysis combines: (i) high-resolution radar-derived rainfall fields (QPEs; 125 m / 6 min), (ii) projected precipitation intensification derived from the ETCCDI R99p index for the 2021–2050 period using HighResMIP (CMIP6) models, (iii) a 40% urban expansion scenario generated through a Cellular Automata model under both traditional and SUDs-oriented development, and (iv) distributed hydrological simulations using the Hillslope Link Model (HLM). The analysis evaluates four configurations: current conditions (CTL), climate change only (CC), land-use change only (BAU/SUDs), and combined scenarios. Results show that the selected climate projection (FGOALS-f3-H) indicates a 12.13% increase in the R99p index, which, when applied to a severe historical storm, produces peak-flow increases of approximately 20% in the Aburrá–Medellín River. Urbanization alone raises peak flows by around 10–17%. When both drivers act simultaneously, peak discharges increase by 30–35% in the main channel and up to an order of magnitude in small tributaries draining steep hillslopes. These nonlinear responses reveal strong spatial heterogeneity across the watershed. Mitigation strategies play a key role: under a Sustainable Urban Drainage Systems (SUDs) scenario, peak-flow increments are reduced by roughly 10–11% relative to business-as-usual expansion, particularly within projected growth areas. Overall, the findings demonstrate that mid-century climate and land-use trajectories could substantially intensify flood hazards in the Aburrá Valley, underscoring the need to integrate infiltration-enhancing urban infrastructure and risk-informed planning into future territorial development.

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