仙台藩祖伊達政宗は1600年（慶長5）暮れに居城を岩出山（現 宮城県大崎市）から仙台の青葉山に移した．関ヶ原の戦いが終わったとはいえ，上杉景勝に対する臨戦態勢を貫いて青葉山に仙台城を造ったといわれる．そして，未開の地である広瀬川対岸の河岸段丘地に城下町を開いた．家臣はじめ約5万人といわれる人々の生活用水及び消防用水の確保を保証することができると判断したのである．しかしながら今日までこの水不便な河岸段丘地にあって，どうして生活用水が確保できたのかについての論究がない．そこで湧水の記録調査及び地形・地盤調査資料を統合的に解析したところ，城下町の地形・地盤には豊かな地下水層が形成され，生活用水を供給することが可能な貯水構造の存在を明らかにすることができた．

Legal regulations related to various laws and prefectural ordinances were investigated in view of promoting geo-heat systems using groundwater in Miyagi Prefecture. It was clarified that there were four major issues: (1) the clarification of the applicable scope of “industry” in the Industrial Water Act, (2) the problems with pumping wells outside the definition of the Industrial Water Act, (3) the deregulation of groundwater pumping only for geo-heat systems, and (4) the deregulation of underground seepage in groundwater restoration. As a result of inquiries and discussions about issue (4) with Miyagi Prefecture, Sendai City, and the Ministry of the Environment, Miyagi Prefecture revised their ordinance that if water is returned to the same aquifer from which it was pumped without changing the quality of the water, it does not correspond to underground seepage. Regarding issue (2), the prefecture and city allowed multiple unregulated pumping wells with discharge openings 6 cm² or less of total cross-sectional areas to be installed on the same site to pump water from aquifers shallower than 300 m regulated. These revisions and permissions to the law and ordinance are expected to expand the use of geo-heat systems using groundwater in Miyagi Prefecture.