Geological analysis and accommodation space
Summary of key issues:
|Description||Review of geological controls and constraints on estuaries that may affect top-down modelling predictions.|
|Temporal applicability||Long-term, centuries and longer.|
|Spatial applicability||Estuary wide.|
|Links with other tools||Forms part of the conceptual understanding of a system.|
|Data sources||Generally, site visits can be used. However, for an in-depth assessment of the constraints of the accommodation space an extensive network of boreholes is required that can be analysed by expert geologists.|
|Key issues||Geology described as limiting or constraining since estuarine tidal flows rarely capable of eroding solid geological substrate.
The geological substrate resulting from interaction of pre-Holocene geomorphological processes and lithology, defines the estuary accommodation space.
Accommodation space constraints to steady state estuarine development principally involve estuarine length and width. Accommodation space depths are in most cases greater than necessary and have been infilled by tidal sediment.
|Necessary software tools / skills||Background knowledge of geomorphology.|
|Typical analyses||In its most general form a broad-brush and long-term assessment of the trends and constraints on the estuary system.
Specialist study of the geology/sediments of the estuary to reveal how the estuary has changed since the Holocene provide a valuable contribution to the conceptual understanding of the estuary.
|Limitations||In its most general form the method relies upon the experience of the geomorphologist in relating his/her experience of other systems to a specific estuary.
In-depth analysis of accommodation space requires specialist study of the geology/sediments of the estuary.
|Example applications||Humber Holocene Chronology|
Understanding the geological context of an estuary can provide additional evidence of the past and current behaviour of the system. The geological context relates to the suite of inherited materials in which the estuary resides, and strengthens the basis on which the conceptual model for that system is developed.
Estuary management decisions usually relate to the medium timescale of, for example, 50 to 100 years and predictions of morphological change, and therefore estuary studies and modelling, are often needed as input to the decision making process. At this scale, the geological context of time development and the influence on estuary form is often relevant. However, for longer-term issues, the underlying geology may have a significant impact. Additionally, even for shorter time scales when attempting to understand the historical evolution of the estuary the influence of geology on this historical change needs to be considered.