[A-HW26] Water Environment and Geology in Urban Areas

[AHW26-P02] Role of groundwater seepage in maintaining low flows in a concrete-lined urban river - A case study in Nomi-gawa river, Ohta Ward, Tokyo, Japan -

Atsushi Fujioka¹, *Masaya Yasuhara², Yuichi Suzuki², Seongwon Lee², Takashi Nakamura³, Noritoshi Morikawa⁴ (1.USEN Corporation, 2.Rissho Univ., 3.International Research Center for River Basin Environment, Univ. of Yamanashi, 4. Geological Survey of Japan, AIST)

Keywords:Tokyo metropolitan area, concrete-lined urban river, maintenance of low river flow, groundwater seepage

Role of groundwater seepage in maintaining low flows in a concrete-lined urban river was studied in Nomi-gawa river, Ohta Ward, Tokyo, Japan. Despite concrete-lining side walls and river bed, groundwater seeps out through gaps of concrete walls and discharge pipes to make a contribution for the formation of river flows. On the basis of electric conductivity, it was made clear that this kind of groudwater seepage accounts for in the range between 10% (20 Jan., 2018) and 35% (26 Oct., 2015) of low flows in Nomi-gawa river.