The potential alternative uses of dredged material in the Humber Estuary
Thesis or dissertation
- © 2012 Jemma-Anne Lonsdale. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
The Humber Estuary handles around 16% of the UK’s maritime trade. It is important for Economic reasons with a number ports and wharves as well as for the environment, with local, national and international designations applied to numerous species and habitats. Associated British Ports (ABP) (as well as other port operators) routinely dredges parts of the estuary for the safe navigation of vessels. Occasionally developer’s capitals dredge new areas to create new or deeper channels or berth pockets in order to remain economically competitive.
This study has investigated the alternative uses of the maintenance and capital dredged material which is usually disposed of within the estuary, to alternative suitable locations within the Humber Estuary whilst taking into account the sediment composition and hydrodynamics, as well as the local need, economics and adherence to the 7 tenets of sustainable development.
The potential use locations were based primarily on the sites that have been identified by the Environment Agency (EA) has having flood defences in less than favourable condition. These locations were characterised by the sediment type, quantity of material needed to ensure protection, average flow velocities at the sites and distance from the dredge site.
By disposing of this sediment within the estuary, it keeps it available to maintain the equilibrium; however this material could potentially be used as a resource to reduce erosion and protect the flood defences behind along the banks of the Humber.
Maintenance dredging involves the removal of the recently settled sediment that contributes to the sediment budget (sediment within a system at one time including the sources, sinks and processes). Therefore only those options that allow the sediment to remain part of the budget have been considered. After taking into account the considerations identified above, this study has indicated that the maintenance dredge arisings could potentially be used for the creation of berm breakwaters within the estuary in order to protect the shore and flood defences behind from erosion and the continuation of disposal within the estuary.
Capital dredging occurs rarely in order to create new channels or berths for new or expanding ports. As capital dredge arisings do not contribute to the sediment budget more options were available to investigate. Dependant on the material type, quantity and distance between the dredge and disposal sites, the alternative uses include the construction of berm breakwaters, intertidal enhancement and also the continuation of disposal within the estuary.
Potential alternative uses for the maintenance and the proposed capital dredge arisings from the Humber Estuary have been identified taking the considerations above into account. The organisations that carry out the dredging operations however are different to those who would require the material for the potential uses identified; therefore there would be difficulties in combining the projects. From this study it appears that due to the designations of the estuary and the characteristics of the dredged material, the continuation of within estuary disposal is the most suitable method of disposal at this time. As it has fewer constraints associated with it, requires less monitoring and also appears to have more neutral than detrimental effects on the estuary than other identified potential uses. From monitoring past published charts and the dynamics of the estuary, historically there is no evidence to prove that this method of disposal negatively affects the estuary’s functioning.
Further work including a detailed field investigation to determine the local and estuary wide effects of the proposed potential uses identified in this study on the environmental, hydrographical, sediment transport and economic aspects. This study is time and site specific for the identified potential uses on the Humber Estuary however the criteria used can be applied to future projects and on other estuaries.
- Department of Biological Sciences, The University of Hull
- Elliott, M. (Michael), 1952 November 3-; Manson, Susan (Flood and coastal risk management advisor)
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