Runoff Analysis Using Multiple Isotope Tracers in the Iwami River Drainage, Akita, Japan

The rate of direct runoff was determined after a heavy rain fall in the Iwami River drainage (ca. 100km2), based on changes in hydrogen and oxygen isotopic ratios and tritium content of river water. The runoff of dissolved components was also estimated from the change in chloride content. Isotopic and chemical characters of base flow were examined at 15 points within the drainage. The latitude and longitude values of the study area are as follows: Min. Latitude: 39deg.42min. N Max. Latitude: 39deg.42min. N Min. Longitude: 140deg.18min. E Max. Longitude: 140deg.18min. E