Ecohydrology is a rapidly evolving interdisciplinary field. It explores the interactions among the variety of hydrological processes and ecosystems, specifically water controls on the biota. Advances in measurement techniques and modeling frameworks have enhanced our understanding of key processes, such as vegetation-rainfall interactions, soil moisture dynamics, water-borne disease infections, and the impacts of landscape evolution on streamflow. However, most existing ecohydrological models rely on rigid, predefined components and parameterisations, which limit their flexibility to diverse case studies and datasets. Addressing these limitations requires the implementation of open-source modular frameworks that facilitate customization, comparison, and integration of several modeling components.</p> <p>The present study introduces and validates GEOSPACE (Soil-Plant-Atmosphere Continuum Estimator), a flexible, open-source ecohydrological framework within the GEOframe system. GEOSPACE employs object-oriented programming principles to model mass and energy fluxes within the critical zone, focusing on processes such as evapotranspiration, soil water dynamics, and vegetation water uptake. Its modular architecture offers multiple alternative formulations for key processes, allowing researchers to tailor simulations to specific scenarios, compare different models, and extend the capabilities of the model. The study uses data from a previous experiment to demonstrate the effectiveness of GEOSPACE in simulating ecohydrological processes under diverse conditions. GEOSPACE is therefore identified as a valuable tool for addressing critical ecohydrological challenges, paving the way for innovative and reliable solutions in a changing environmental context.