ABSTRACT
The dynamic nature of coastal landscapes and the inherent complexity of the biophysical processes operating in these environments challenge the application of GIS methods. It is well recognised that spatial data models representing static objects are rife with uncertainty (Fisher, 1999; Foody, 2003). However, the mobility of many coastal and marine phenomena and the nebulous nature of boundaries in these environments provide an additional dimension to the problems associated with spatial data uncertainty. In abstracting the infinite complexity of reality into a finite computer based storage structure, multiple levels of uncertainty are introduced. The more encompassing or inclusive a data set, often the more complex the process of abstraction. Users of coastal and marine GIS are faced with both uncertainty in the information derived from spatial data, and uncertainty that inherently exists in the models. The ubiquitous nature of uncertainty in spatial analysis highlights the need to examine the implications for coastal and marine decision-making. This chapter examines the sources of uncertainty, methods for assessing reliability, model uncertainty and the cognitive and practical implications associated with the communication and incorporation of uncertainty in coastal and marine GIS.
