This study proposes the specification of a Tangible landscape (TL) to be used in the educational setting of a landscape design atelier. The main learning outcomes are to design alternative waterways in a riverine area taking into consideration the impact of waterflow on the landscape as a result of the designed waterways. TL is a projection-augmented sandbox powered by a Geographical Information System (GIS) for real-time geospatial analysis and simulation by coupling a mock-up with a digital model in near-real time by using 3D sensing, enabling users to apply geospatial simulation and visualisation. Notwithstanding the proven qualities of using TL in an educational setting, some obvious topics are addressed regarding the role of TL in educating waterway design. These topics are; how to realize a reusable and semi-realistic mock-up, in what way could waterways be designed without disrupting the mock-up, and how to give appropriate feedback during the design of waterways regarding the impact of waterflow change. The specified TL includes a thread-based approach that enables the student to design without disrupting the mock-up. Besides near real-time iterative results – both visually and numeric – it shows the hydrologic impact of the designed waterway. The expected outcomes of the current TL in education may stimulate topological thinking and insight into riverine geomorphology, it fosters representative and integrative thinking because of the near real-time relation between the design (form, scale, size) decisions and hydrologic process impact which makes the impact of design decisions on hydrological processes more illustrative and tangible.