Land-ocean interaction: processes, functioning and environmental management from a UK perspective: an introduction.

This paper provides a foreword to a special edition of Science of the Total Environment concerned with land-ocean interaction from a UK perspective as linked to processes, functioning and environmental management. The volume structure is presented together with an outline of the nature of the individual papers. The areas covered are: (1) freshwater chemistry, (2) riverine sedimentology, (3) tidal river, estuarine and coastal chemistry, (4) estuarine and coastal sediments and (5) shelf-sea-ocean linkages. The foreword provides as an introductory link to the broader perspectives of contemporary UK research in this area, which comes in a conclusions paper at the end of the volume.

ECoS, a framework for modelling hierarchical spatial systems.

A general framework for modelling hierarchical spatial systems has been developed and implemented as the ECoS3 software package. The structure of this framework is described, and illustrated with representative examples. It allows the set-up and integration of sets of advection-diffusion equations representing multiple constituents interacting in a spatial context. Multiple spaces can be defined, with zero, one or two-dimensions and can be nested, and linked through constituent transfers. Model structure is generally object-oriented and hierarchical, reflecting the natural relations within its real-world analogue. Velocities, dispersions and inter-constituent transfers, together with additional functions, are defined as properties of constituents to which they apply. The resulting modular structure of ECoS models facilitates cut and paste model development, and template model components have been developed for the assembly of a range of estuarine water quality models. Published examples of applications to the geochemical dynamics of estuaries are listed.

Apparent homeostasis in the surface salinity of a turbid macrotidal estuary.

A simple, one-dimensional tide-ignoring model has been fitted to surface salinity measured at monthly intervals over 3 years on an extensive sampling grid in the Humber and tidal Ouse on the North Sea coast of the UK. With a constant and uniform axial dispersion, estimated at 296+/-7 m2 s(-1) (95% confidence limits), model deviations vary systematically in space and time. Postulating an influx of dispersive tendency with fresh water largely eliminates the systematic variation in space. Deviations from the simple model (observations-predictions) show a significant seasonal cycle, with minima in the summer and maxima in the winter, and decline significantly over the 3 years of the study. A model that incorporates a homeostatic tendency for the estuary to revert to a constant salinity profile, independent of river flow, appears to eliminate both the seasonal cycle and the trend. The half time of the homeostatic process is estimated to be between 76 and 97 days (95% confidence limits). It is concluded that sediment movement might be the basis of such a mechanism.

Land Ocean Interaction: processes, functioning and environmental management: a UK perspective.

The hydrochemical and physical functioning of UK river basins, estuaries and coastal waters through to the open sea are outlined in relation to British environmental research over the last ten or more years. An overview of a considerable body of published work is presented in the context of current findings and future research challenges. This is linked to this special issue of Science of the Total Environment 'Land Ocean Interaction: processes, functioning and environmental management: a UK perspective' for which this contribution provides a conclusion.