Although complex hydrological models with detailed physics are every day more common, lumped and semi-distributed models are still used for many applications and offer some advantages as its reduced computational cost. Most of these semi-distributed models use the concept of Hydrological Response Unit or HRU. In its original conception, HRUs are defined as homogeneous structured elements having similar climate, land-use, soil and/or pedotransfer properties, hence a homogeneous hydrological response under equivalent meteorological forcing. This work presents a quantitative methodology to construct HRUs based on Principal Component Analysis and Hierarchical Cluster Analysis of gridded meteorological data and hydrological parameters. The methodology is tested using the Water Evaluation and Planning System (WEAP) model for the Alicahue River Basin, a small catchment in Central Andes, in Central Chile. The results show that with four HRUs it is possible to reduce up to about a 10% the relative within variance of the catchment, an indicator of homogeneity of the HRUs. Evaluation of the simulations show a good agreement with streamflow observations in the outlet of the catchment with a NSE value of 0.79 and also show the presence of small hydrological extreme areas that generally are neglected due to their relative size.