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| Titel |
Seasonal change of residence time in spring water and groundwater at a
mountainous headwater catchment |
| VerfasserIn |
Kosuke Nagano, Maki Tsujimura, Yuichi Onda, Sho Iwagami, Koichi Sakakibara, Yutaro Sato |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140461
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| Publikation (Nr.) |
 EGU/EGU2017-3857.pdf |
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| Zusammenfassung |
| Determination of water age in headwater is important to consider water pathway,
source and storage in the catchment. Previous studies showed that groundwater
residence time changes seasonally. These studies reported that mean residence time of
water in dry season tends to be longer than that in rainy season, and it becomes
shorter as precipitation and discharge amount increases. However, there are few
studies to clarify factors causing seasonal change in mean residence time in spring
water and groundwater based on observed data. Therefore, this study aims to reveal
the relationship between mean residence time and groundwater flow system using
SFconcentration in spring and 10 minutes interval hydrological data such as discharge
volume, groundwater level and precipitation amount in a headwater catchment in Fukushima,
Japan.
The SF6 concentration data in spring water observed from April 2015 to November 2016
shows the mean residence time of springs ranged from zero to 14 years. We also observed a
clear negative correlation between discharge rate and residence time in the spring. The
residence time in shallow groundwater in rainy season was younger as compared with that in
low rainfall period. Therefore, the shallow groundwater with young residence time seems to
contribute to the spring in rainy season, causing shorter residence time. Additionally, the
residence time of groundwater ranged from 3 to 5 years even in low rainfall period.
The residence time in high groundwater table level in ridge was older as compared
with that in low groundwater table level. These suggest that the contribution of
groundwater with older age in the ridge becomes dominant in the low discharge. |
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