| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2013: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2012: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
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| Outline of Final Research Achievements |
The hyporheic zone plays several important roles in stream ecosystems. It is a dynamic zone, yet few studies examined the factors controlling its change in extent. In this study, vertical hydraulic head gradient (VHG) and fine sediment concentration in the hyporheic zone were monitored to investigate the dynamic nature of the hyporheic zone. The study sites were located in step-pool sequences in steep headwater streams. During precipitation events, pressure from hillslope increased, and the upwelling trend increased, whereas VHG did not change in the downwelling zone. Fine sediment concentration in the downwelling zone increased after the high flow events, but hydraulic conductivity did not changed and stayed high. Therefore, contrary to previous understanding, the extent of the hyporheic zone was stable in steep headwater streams, though the concentration of fine sediments and fraction of organic matter changed during high flow event, so the environment changed over time.
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