Watershed Selection

For each landscape area on which land cover change is simulated, a set of gridded maps must exist. The integration of socioeconomic and ecological variables is accomplished spatially through the use of these gridded maps. Individual maps may represent a single data theme which describes physical landscape attributes (e.g., land cover, slope, soil type), spatial features (e.g., distance relationships, adjacency rules), the results of socioeconomic and ecological processes (e.g., changes in real estate values, species abundance, and erosion), and land-ownership characteristics (e.g., tract size, shape, and history). Pixels in each map are assigned to one of the discrete categories used to describe that data theme [B92].

Currently, a set of gridded maps exist for three study areas: the Little Tennessee River Basin, the Hoh Watershed, and the Dungeness Watershed. The LUCAS user must choose one of the available watersheds prior to running the simulation. To display the watershed selection, the LUCAS GUI utilizes the Motif XmScrolledList widget. The XmScrolledList widget allows the user to select the watershed on which they would like to simulate land cover change. Selection occurs when the user points-and-clicks on an item in the list. The XmNsingleSelectionCallback resource specifies the callback routine which determines which watershed was selected. The list of watersheds is not hard-coded, but is instead generated at run-time by parsing the names of the available scenario files. The format of the scenario filenames is location-watershed-depvar-scenario-title-year, where location indicates the watershed that the scenario has been prepared for and depvar represents the dependent variable of the simulation. The scenario files are located in a directory indicated by the LUCAS_DIR environment variable. The LUCAS GUI parses each filename in the LUCAS_DIR directory and creates the scrolled list of watersheds.