What is the Desk Based Study (DBS)?

Following consultation from key stakeholders, the DBS forms an initial part of the FA and is ideally undertaken prior to the field reconnaissance survey (catchment baseline survey).

Reports, GIS layers, remotely sensed data, contemporary and historic maps, available sediment budget data, and fluvial data (derived from numerical models) are used to provide a broad, background understanding of the catchment and its key hydrogeomorphological issues (Sear,  Newson, and Thorne, 2010)(Figure. 1).. The DBS also clarifies where further data is needed on the physical, localised channel dynamics.

Remote sensing methods are used to supplement the DBS, through the provision of aerial photography, terrestrial lidar, satellite imagery  and bathymetric data, where available.  The use of GIS allows for the coherent storage and analysis of multiple spatial data sources. Whilst some data sets are open source, provided by government bodies on a wide variety of catchments and individual water courses (flow rates, stage height, imagery etc.), other data sets are not easily attainable (e.g. sediment calibre, channel geometry).

Figure 1. Examples of data that can be used to inform the desk based study and post project appraisal, measured across varying spatial and temporal scales (Sear,  Newson, and Thorne, 2010).

 

The DBS provides the preliminary understanding of the catchment, highlighting areas of potential vulnerability and sensitivity which can later be assessed in greater detail. By identifying areas of potential sensitivity, this streamlines the FA process, as the areas highlighted as sensitive can be prioritised for surveying, particularly so when funding or field surveying time is limited (Environment Agency, 2005).

Click here to view the GIS analysis of the Cuckmere River, in part fulfilment of the FA. Whilst the data presented within the GIS presented describes and illustrates a variety of topographical information on the Cuckmere catchment, further information, of which is not spatially illustrated – click here to view additional data, that can be used to inform the desk based analysis of this survey. 

References

Environment Agency, (2005). Method Description (Report A). Fluvial Audit – A Method for Catchment-Scale Geomorphological Assessment. [online] pp.2-19. Available at: <https://www.therrc.co.uk/sites/default/files/files/Designated_Rivers/Axe/fluvial_audit_-_method_description_-_report_a_-_final_a01.pdf> [Accessed 19 March 2021].

Sear, D., Newson, M. and Thorne, C., (2010). Guidebook of Applied Fluvial Geomorphology. London: Thomas Telford, Pp.22-134.