The coastal zones are considered vulnerable to the impacts of climate change. Although groundwater is one of the most significant water sources for agriculture and domestic demands in Ecuador central coast, there are limited studies regarding the evaluation of the resources as well as the impact of the aquifers on global change scenarios. Development of adaptation strategies is needed to increase resilience on aquifers systems. During the last two decades, groundwater usage in the coast of Ecuador has increased abruptly due to socioeconomic growth, desertification and drought problems. Aquifers impact assessment studies under global change scenarios are scarce. This study aims to improve an existing Decision Support System (DSS) developed in the framework of ADMICCO project, by establishing the current and future state of the available groundwater resources for Portoviejo city and its areas of influence and identify effective action strategies at the local level that contribute to increase the resilience of the population in the face of floods and droughts. In this study, the groundwater resources of Portoviejo were evaluated by modelling with GMS-MODFLOW. By applying different calibration methodologies, it was possible to analyse the water balances and fluxes of the aquifer. A calibration deviation map was produced to identify the potential areas to improve the calibration and the monitoring network. Finally, scenarios were simulated: 1) ADMICCO future climate change recharge scenario in the wet season, 2) ADMICCO future socio-economic water demand scenario in the wet and dry season and 3) previous scenario plus the implementation of ancestral groundwater management technics. The current study is pioneering in modelling “Ancestral” groundwater management technics integrated with the so-called Manage Aquifer Recharge Technics as an adaptation measure for climate change scenarios in Portoviejo Aquifer.