首页 | 本学科首页   官方微博 | 高级检索  
     


On different time scales of suspended matter dynamics in the Weser estuary
Authors:Iris Grabemann  Gunther Krause
Affiliation:1. Institut für Küstenforschung, GKSS Forschungszentrum Geesthacht GmbH, Postfach 1160, 21494, Geesthacht, Germany
2. Alfred-Wegener-Institut für Polar- und Meeresforschung, Postfach 120161, 27515, Bremerhaven, Germany
Abstract:Long-term observations in the Weser estuary (Germany) between 1983 and 1997 provide insight into the response of the estuarine turbidity maximum (ETM) under a wide range of conditions. In this estuary the turbidity zone is closely tied to the mixing zone, and the positions of the ETM and the mixing zone vary with runoff. The intratidal suspended particulate matter (SPM) concentrations vary due to deposition during slack water periods, subsequent resubsequent and depletion of temporarily-formed and spatially-limited deposits during the following ebb or flood, and subsequent transport by tidal currents. The corresponding time history of SPM concentrations is remarkably constant over the years. Spring tide SPM concentrations can be twice the neap tide concentrations or even larger. A hysteresis in SPM levels between the falling and rising spring-neap cycle is attributed to enhanced resuspension by the stronger spring tidal currents. There is evidence that the ETM is pushed up-estuary during times of higher mean water levels due to storms. During river floods the ETM is flushed towards the outer estuary. If river floods and their decreasing parts occur during times of relatively high mean water levels, the ETM seems to be maintained in the outer estuary. If river floods and their decreasing parts occur during times of relatively low mean water levels, the ETM seems to loose inventory and may need up to half a year of non-event conditions to gain its former magnitude. During this time seasonal effects may be involved. Analyses of storm events and river floods have revealed that the conditions in the seaward boundary region play an equally important role for the SPM dynamics as those arising from the river.
Keywords:
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号