Optimum Architetcure for Sustainable Irrigation System:OASIS
Sendai OASIS (Optimum Architecture for Sustainable Irrigation System) is an experimental design project based on Green infrastructure Urbanism. Finding an optimum solution for Climate Change issues, Sendai OASIS intends to expand a potential relation between man made living environment design and ecological sustainability into a new Smart community vision focusing on the existing rain water resources. Before the pre-industrial period in Japan, the most sophisticated water landscape design in the man made living environment is often to be found with the Sustainable Irrigation System. Tsuujunkyo aqua duct in Kumamoto or Hakushuientei dam in Oita in the western Japan, explain the distinctive features of those examples. The Igune Green Island (wind break wood around farmhouse ) floating on the Sendai Plains well defines the OASIS potential even today.
Rich agriculture fields in front of the Sendai city centre has strong linkage with water resources from Hirose river in connection with the distinctive fluvial terrace’s geological and topological features. OASIS contributes to preserve not only a productive paddy field but also stimulates the environmental integrity that accelerates rich food chain and bio-diversity constantly, thus qualified agri-products are permanently maintained. 400 years Igune’s history consistently proves this simple fact that sustainability seems relevant even in the 21st century. However those precious fields have been heavily damaged by the East Japan Great Earthquake in March 2011. In the reconstruction process from this disaster those insights should be reexamined and innovated into advanced Smart Water City design.
In Japan Global Warming and Climate Change Issues are mostly regarded as Torrential Rain syndrome and Heat Island phenomenon especially in metropolitan environments. Torrential Rain phenomena (Guerrilla Rain) cause inundation damage in the lower urban area and underground transportation infrastructure crucially paralyzing urban living. Current sewer infrastructure in Japan both for combined and separate system, hold potential negative environmental impact such as direct contaminated water leaks into the sea after the torrential runoff rain passes through the urban zone. Research estimates the inundation damages of the Kanda river area in Tokyo was worth $0.15 billion, thus to reduce inundation an underground regulating mega reservoir infrastructure was constructed with cost of $1billion for 4.5km length
On the other hand, Heat Island phenomenon leads higher air temperature environment in the high density city centre than that in suburban and rural areas. The average global mean temperature increase tends to be accelerated according to IPCC reports ,which urges urban climate control using optimum environmental measures. Research shows that the Heat Island phenomenon affects not only the increase of energy consumption but also health care issues related to heat stroke patient ratio.