| Land-surface processes include a broad class of models that operate at a
landscape scale. Current modelling approaches tend to be specialised towards
one type of process, yet it is the interaction of processes that is
increasing seen as important to obtain a more integrated approach to land
management. This paper presents a technique and a tool that may be applied
generically to landscape processes. The technique tracks moving interfaces
across landscapes for processes such as water flow, biochemical diffusion,
and plant dispersal. Its theoretical development applies a Lagrangian
approach to motion over a Eulerian grid space by tracking quantities across a
landscape as an evolving front. An algorithm for this technique, called level
set method, is implemented in a geographical information system (GIS). It
fits with a field data model in GIS and is implemented as operators in map
algebra. The paper describes an implementation of the level set methods in a
map algebra programming language, called MapScript, and gives example program
scripts for applications in ecology and hydrology. |