Incorporating Level Set Methods in Geographical Information Systems (GIS) for Land-Surface Process Modeling

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