Which factor is critical in the design of green infrastructure for stormwater management?

Soil permeability plays a crucial role in the design of green infrastructure for stormwater management because it directly influences how water infiltrates the ground, thus affecting drainage efficiency and groundwater recharge. Properly designed green infrastructure relies on the ability of soil to absorb and filter stormwater, minimizing runoff and reducing the risk of flooding and erosion. Understanding the characteristics of soil permeability allows planners to select appropriate green infrastructure techniques, whether it's bioretention areas, green roofs, or permeable pavements, ensuring that they perform effectively in the specific environmental context.

While cost of materials, availability of land, and species biodiversity are all important considerations in the planning and implementation of green infrastructure, they do not have the direct impact on hydrological performance that soil permeability has. Cost affects the feasibility and sustainability of projects, land availability dictates where projects can be done, and species biodiversity contributes to ecological benefits, but none are as integral to the fundamental functioning of stormwater management systems as soil permeability.