Earth & Environment

10-7-2007

Coastal typologies

2007 | UU | research

http://geotypes.net

Global Coastal Typology and its application to lagoons

I did my Master's thesis at Utrecht University. It was a research which was both supervised by the geochemistry department and the Physical Geography department. The research group my work was part of was GNUX, which had multiple phd and postdoc candidates researching global nutrient fluxes from the continent, through the coast and in the ocean. My work focussed on the coast and lagoons especially.  

The abstract is given hereunder. The full text can be downlowded here: cvkempen_Gnux2007.pdf (17 Mb)

The coastal typology was further finalized by my supervisors and is now available from: http://geotypes.net

I would hereby want to extend my gratitude to my supervisors Goulven Laruelle and Hans Dürr, who pulled me through the endeavour and from whom I have learnt so much. They really put a lot of time in supverising and it was a really great time with a nice result. 

 

Towards a global coastal typology for modelling nutrient fluxes at the land-ocean interface: an application to lagoons.

Cheryl M. Van Kempen(1), Goulven G. Laruelle(1), Hans H. Dürr(2), Caroline P. Slomp(1), Hans Middelkoop(2), Michel Meybeck(3)
(1) Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, The Netherlands
(2) Department of Physical Geography, Faculty of Geosciences, Utrecht University, The Netherlands
(3) UMR Sisyphe, Université Paris VI, France

Abstract

deltaNutrients, and in particular nitrogen (N) and phosphorus (P) play important roles in both terrestrial and aquatic ecosystems, as they are essential to sustain primary production. Sudden excessive increases in nutrient availability however also have the potential to disrupt ecosystem balance and its ability to provide ecosystem services. As a large part of the world population depends on coastal ecosystem services for their livelihoods, such as fishing and tourism, there is a particular interest to understand the biogeochemical cycles and to estimate nutrient levels of N and P in the coast world wide. To achieve this at the global scale, means for upscaling available data to uncovered areas are required. GIS allows a spatial typologic approach to coastal biogeochemical research, as will be shown here.estuary

 

In the present thesis, the first steps are made towards the development of a geochemically relevant coastal segmentation which, in future work will be coupled to generic nutrient box-models. The ensemble of segmentation and models will allow estimating nutrient levels and retention in coastal systems anywhere on earth. Here, the first preliminary steps are set, by developing a coastal typology and lagoon nutrient model.

lagoonA coastal segmentation (at 0.5 - 0.5 degrees resolution) is presented here, which is biogeochemically relevant and in which all segments were classified according to a filtering typology. The classes (I, II, III and 0) represent both the magnitude and processes driving nutrient filtering in estuarine, lagoon and fjord-like coasts and finally coasts where no relevant biogeochemical activity takes place in the proximal coastal ocean, but instead in the distal coastal ocean. Each of these types makes up 40, 10, 30 and 20% of the world's coast respectively, and they receive 30, 7, 10 and 53% of the global annual runoff. The coastal segmentation was obtained by aggregating classes of a morphologic typology, also presented here. The 11 morphologic classes represent karst, fjord, fjärd, ria, macrotidal, estuarine, lagoon, big river, mangrove, arheic and glaciated sedimentary coasts.

fjordTo assess the complexity in terms of the mathematical representation of the nutrient fluxes the generic nutrient model can have, three site specific models are presented here for type II (lagoon coasts). They are applied to Thau, Venice and Szczecin lagoons and are simple, coupled, multi-element (N and P), multi-form (dissolved/particulate, organic/inorganic), process-based box models. All processes are represented by rate constants, and depend only on the source reservoir. The importance of exchange of water between the lagoon and the sea is assessed, as well as a sensitivity analysis, comparison of rate constants a simulation of Szczecin lagoon for the period 1980 to 1999 and finally an assessment of the effect of the N:P ratio for consumption on lagoon biogeochemistry.

The results show

    1. that exchange with the sea must be included in a lagoon model;
    2. primary production and remineralisation cannot be represented well by first order kinetics alone and
    3. the ratio at which N and P are consumed during photosynthesis affect DIP and primary production considerably.

Preliminary Global Coastal Typology

(for Nutrient filtering at the land-ocean interface)

 

 

Typology
legend
RED - Type I. (like estuarine filtering)
GREEN - Type II. (lagoon-like)
BLUE - Type III. (fjord-like)
BROWN - Type 0. (no filtering, so including both arid regions and big rivers)

 

note that here only preliminary work is presented and that a future typology will include a Type IV. (for delta-like filtering) see http://geotypes.net

Morphology
Graduated.jpg
       Just to end with a nice picture of what this research brought me: graduation and a Drs title! Behind me stand Goulven Laruelle (left) and Hans Dürr, my supervisors.