Small-scale hydrology is vital to landscape architecture, particularly in urban environments where water management must integrate functionality with visual appeal. Artful Rainwater Design (ARD) emphasizes creating sustainable, expressive landscapes that celebrate water's dynamic behavior while managing stormwater. This research began with a preliminary evaluation of approximately 20 computational tools, narrowing the focus to three – Flow3D Hydro, Autodesk CFD, and Blender, for detailed analysis. Using the Flow Box test, we measured flow behavior variables such as flow rate adjustments, water drops, splashes, and visualization capabilities to assess each tool's reliability, accuracy, and usability. The findings demonstrate the potential of computational simulations to capture complex water interactions in ARD, providing valuable insights into simulation criteria for designing functional and visually engaging water management systems in small-scale applications.