Green roof (or more specifically, vegetative roof) designers design extensive and intensive roof gardens for stormwater management, evapo-transpirative cooling, sustainable architecture, aesthetics, and habitat creation.[13].
Blue roofs are a sustainable stormwater management technique designed to mitigate urban flooding with growing evidence they work well at this.

Such details provide a deeper understanding and appreciation for Green Roof Technical Specifications For Flood Control.
J-Drain Greenroof Catalog. Green Roof Technical Specifications. Architectural Specification Sheet. Product Datasheet.

The Technical Specifications include guidelines on green roof design, construction, and management. It requires new buildings to have rooftop gardens, and it also mandates old buildings to have safety testing before building the gardens.
D. Green Roof Provider Information: Technical product data or bulletins, specifications, LEED submittals, installation guide and maintenance protocols. E. Certifications (optional): Verification that Installer is qualified to perform work of this Section.