Flow characteristics of artesian groundwater in coastal area of Kurobe River basin, Toyama Prefecture, by long-term and spatial observation of water temperature and electric conductivity

Long-term (9 years from 2011) and spatial (106 points in 2012 and 2013) observation of water temperature and electric conductivity were conducted for groundwater and river water throughout the Kurobe River basin to clarify the recharge area and recharge situation for the safety use of groundwater resources. The results of these observations show that the water temperature of the river rose in the lower basin (0.3 °C/100 m), but that the temperature of the coastal area was lower than the annual average. The EC rises further away from the river, indicating that Kurobe River water have been infiltrated into ground and the interaction with the rocks is progressing. Most groundwater in the alluvial fan was recharged from the top of the fan; however, the coastal area was recharged from a river about 142–450 mASL (about 13–34 km from an estuary of the Kurobe river).