What is green infrastructure?

Overseas, efforts have been underway early on. In the United States, the Environmental Protection Agency (EPA) announced a new strategy to promote green infrastructure in 2011, and progress has been made in establishing and improving systems to improve stormwater management functions, leading to the accumulation of technology related to stormwater drainage.
For example, across the United States, rain gardens are being installed along the sides of roads to prevent rainwater from immediately flowing into the sewer, and to create a system that allows rainwater to slowly seep underground.
In Europe, the European Commission published the European Green Infrastructure Strategy in 2013, which outlined a strategy for promoting the development of green infrastructure in cities and regions of the European Union, including green roofs, green walls, rainwater harvesting, water recycling systems, flood control, and erosion management.

Globally, there has been a growing movement to promote green infrastructure, following the adoption of the Paris Agreement and SDGs in 2015 and the explicit inclusion of green infrastructure at the G2016 Summit in 7.
In Japan, green infrastructure was included in the Ministry of Land, Infrastructure, Transport and Tourism's administrative plans, the National Land Use Plan and the Social Capital Priority Development Plan, in 2015.
Momentum is building with the announcement of the Green Infrastructure Promotion Strategy by the Ministry of Land, Infrastructure, Transport and Tourism in 2019, and the launch of the Green Infrastructure Public-Private Partnership Platform in 2020, which will serve as a platform for collaboration among a variety of entities. Setagaya Ward in particular is creating a system to encourage participation not only from the government and related organizations, but also from citizens, and has set up a GI intra-government collaboration platform within the city hall, creating an environment to promote activities.

Rooftop greening has a variety of functions and effects, such as mitigating the heat island effect, reducing rainwater runoff, creating biodiversity, and saving energy. Therefore, it is not just a green infrastructure development, but is also expected to have functions such as disaster prevention and mitigation, and to provide comfort and relaxation for residents.
As a space for creating biodiversity, it is possible to create a habitat for a variety of organisms by securing a brown roof (organic soil), promoting plant growth, and properly managing the rooftop greenery.
From the perspective of disaster prevention and mitigation, rooftop greenery can be highly effective as a "stormwater runoff control facility" that protects cities from heavy rain disasters caused by recent abnormal weather.

Reference: "Technical guidelines for the installation of temporary storage facilities in public facilities"
(Tokyo Metropolitan Government Bureau of Urban Development, March 28)

Along with green infrastructure, an initiative called Eco-DRR (Ecosystem-based Disaster Risk Reduction) has already begun. This is a concept that utilizes the power of nature to prevent and mitigate disasters, and is a method for creating disaster-resistant communities. In Japan, examples of this include old mixed forests and coastal conservation forests. Sendai's Igune served as a shield during the Great East Japan Earthquake, minimizing damage from the tsunami in many areas, and it can be said that this function was truly demonstrated.