Which factor can significantly alter the drainage requirements for a site?

Changes in land use can significantly alter the drainage requirements for a site because they can directly impact the amount of impervious surface and the flow of stormwater. When land use changes, for instance from agricultural to urban, or from open space to commercial development, the hydrology of the area is affected. Increased impervious surfaces can lead to greater stormwater runoff, requiring modifications in the existing drainage plans to manage the increased volume and velocity of runoff effectively.

Additionally, changes in land use may necessitate new stormwater management practices to mitigate potential impacts on water quality and to comply with updated regulatory requirements. This includes the implementation of facilities like retention basins, bio-swales, or other Best Management Practices (BMPs) that help manage stormwater effectively on the newly developed site.

In contrast, factors like the implementation of green roofs or regular maintenance of existing facilities may improve drainage but do not fundamentally change the underlying land use conditions that drive drainage requirements. Meanwhile, increased property taxes do not have a direct effect on physical drainage requirements, as they more so relate to economic aspects rather than hydrological ones.