Predictive Assessment of the Performance of the Huancayo Rainwater System (Junín) in the Face of Climate Change: An Approach Using Digital Hydraulic Models

Climate change, together with rapid and frequently unplanned urban expansion, is placing increasing pressure on stormwater drainage systems in inter-Andean cities such as Huancayo (Junín, Peru). This study uses the Storm Water Management Model (SWMM) to make a prediction about how Huancayo's stormwater network will work now and in the future based on climate models. Local hydrometeorological records and stormwater infrastructure data are combined and collected to model runoff response, peak discharge, ponded volume, and network overload. Simulations show that under normal conditions for 10 and 100-year return periods, the system has limited capacity. Peak outflows reach about 78 to 121 m³/s, ponded volumes rise to about 62,000 to 145,000 m³, and node surcharge is widespread. In a 2070 projection using RCP 8.5, peak discharge and ponded volume rise by about 21% and 37%, respectively, compared to the baseline. A hybrid green–gray adaptation package that includes detention tanks, Low-Impact Development (LID) practices, collector enlargement, and monitoring support cuts peak flows and ponded volumes by 30% to 46% in baseline conditions and by about 29% to 33% in the future scenario. The findings underscore that predictive hydraulic modeling can facilitate pragmatic adaptation planning and enhance flood resilience in elevated urban catchments subject to climatic variability.