HR: 1340h
AN: H23C-1439    [Abstracts]
TI: The Effect of Bedrock Groundwater on Rainfall-Runoff Process in a Small Headwater Catchment Underlain by Rhyolite
AU: * Tsujimura, M
EM: mktsuji@atm.geo.tsukuba.ac.jp
AF: Graduate School of Life and Environmental Sciences, University of Tsukuba, Laboratory of Advanced Research A, 1-1-1 Ten-nodai, Tsukuba, 305-8572 Japan
AU: Onda, Y
EM: onda@atm.geo.tsukuba.ac.jp
AF: Graduate School of Life and Environmental Sciences, University of Tsukuba, Laboratory of Advanced Research A, 1-1-1 Ten-nodai, Tsukuba, 305-8572 Japan
AU: Urano, H
H23C-1439 AF: Graduate School of Life and Environmental Sciences, University of Tsukuba, Laboratory of Advanced Research A, 1-1-1 Ten-nodai, Tsukuba, 305-8572 Japan
AU: Kawakami, T
H23C-1439 AF: Graduate School of Life and Environmental Sciences, University of Tsukuba, Laboratory of Advanced Research A, 1-1-1 Ten-nodai, Tsukuba, 305-8572 Japan
AB: To evaluate the contribution of bedrock groundwater seepage to stormflow generation, runoff and water chemistry of spring and streamflow were observed in a headwater catchment, namely Anra catchment underlain by rhyolitic rocks, Nikko, Tochigi, central Japan. The ratio of quick flow defined by Hewlett and Hibbert (1967) to the total rainfall of the storm events increased as total amount of the rainfall increased. The peak specific discharge showed a positive correlation with the rainfall intensity, and the slope of the regression line was much higher for the rainstorms with total rainfall over the amount of 100 mm than that less than 100 mm. The major cations and bicarbonate concentrations decreased coinciding with the peak runoff, whereas those concentrations increased and reached at a value higher than that in base flow in the recession limb during the rainstorms with the total rainfall more than 100 mm, in this case, the slope of the recession limb of the discharge tended to be gentler. This suggests that bedrock groundwater with high solute concentrations might contribute much to the runoff in the discharge recession, and the runoff originated from more bedrock groundwater might have a gentle recession limb in the hydrograph.
DE: 1860 Streamflow
SC: Hydrology [H]
MN: Fall Meeting 2005