Flowpaths are significantly affected by land use change and engineered elements across urban catchments. Conventional GIS-based tools for extracting drainage networks were not developed for urban terrains. This work presents Geo-PUMMA, a GIS toolbox to generate vectorial meshes for terrain representation in distributed hydrological modeling, and to extract drainage patterns in urban and peri-urban catchments. Geo-PUMMA generates wellshaped Hydrological Response Units (HRUs) and Urban Hydrological Elements (UHEs). The toolbox was used in peri-urban catchments of Chile and France to generate three model meshes with different levels of treatment, and extract and compare their corresponding drainage networks. A recommended mesh is identified, which replicates the main morphological and hydrological features of the reference drainage network, and is able to preserve features at small to medium spatial scales (~ 80-150 m). Overall Geo-PUMMA can be used to represent the terrain in distributed hydrological modeling applied to urban and peri-urban scales. .

The impact of urbanization on groundwater is not simple to understand, as it depends on a variety of factors such as climate, hydrogeology, water management practices, and infrastructure. In semiarid landscapes, the urbanization processes can involve high water consumptions and irrigation increases, which in turn may contribute to groundwater recharge. We assessed the hydrological impacts of urbanization and irrigation rates in an Andean peri‐urban catchment located in Chile, in a semiarid climate. For this purpose, we built and validated a coupled surface–groundwater model that allows the verification of a strong stream–aquifer interaction in areas with shallow groundwater, higher than some sewers and portions of the stream. Moreover, we also identified a significant local recharge associated with pipe leaks and inefficient urban irrigation. From the evaluation of different future scenarios, we found a sustainable water conservation scenario will decrease the current groundwater levels, while the median flow reduces from 408 to 389 L/s, and the low flow (Q95%) from 43 to 22L/s. Overall, our results show the relevance of integrating the modeling of surface and subsurface water resources at different spatial and temporal scales, when assessing the effect of urban development and the suitability of urban water practices.

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