Deltas are important landforms on Mars because they indicate past fluvial activity, contain a sedimentary record amenable to study, and have the potential to store past signs of life. The sedimentary records that are visible today on satellite and rover images are used to deduce the fluvial and climate history of Mars. To do this we use our understanding of deltas on Earth, as deltas are well-studied landforms. However, when making interpretations it is very important to understand the differences in delta morphodynamics and stratigraphy between Earth and Mars. Even though the processes on Mars are similar, the water discharge, sediment flux, and grain size sorting can be significantly different due to for example gravity, sediment density, presence of ice, and lack of ecology. In this research, we focus on the effect of gravity and its net effect on delta morphology and stratigraphy. From preliminary experiments, we expect a significant effect of gravity on grain size sorting, because suspended sediment (fine grains) is affected more by gravity than bedload transport (bigger grains). In addition, we expect bigger grains to travel in suspension on Mars under the same boundary conditions. We will study the net effect of these water and sediment fluxes on morphology and stratigraphy by numerical modelling in Delft3D. This software is typically used for river and coastal systems on Earth, but we adapted the software by identifying all explicit and implicit dependencies on gravity, so it can also be used for deltas on Mars. We developed a 2DH hydro-morphodynamic model of a simplified delta to test different scenarios. The model consists of a straight channel flowing into a sloping basin. In the comparison between our Earth and Mars scenarios, gravity is the only parameter varied. We are currently experimenting with different upstream boundary conditions that we keep equal between the Earth and Mars scenario. We are testing equal discharge, water level, and sediment input. Equal discharge reveals the effect of gravity on sediment flux, equal water level the effect on water and net sediment flux, and equal sediment supply focusses on the sediment sorting that is mostly overshadowed in the other scenarios by the sediment flux difference.