Original Client Request:

Object-oriented Environmental Models
Larry Band

We are currently operating a spatially distributed model of watershed carbon, water and nutrient dynamics. The model is called RHESSys (Regional HydroEcological Simulation System). Its development and application has been funded by a combination of NASA, NOAA and Canadian Government agencies over the last 10 years. The model produces the spatial distribution of watershed stream flow, ecosystem productivity (net carbon accumulation, forest growth) and nutrient (e.g. nitrogen) cycling.

Inputs include meteorological information from National Weather Service stations which are interpolated into fields of daily temperature, humidity, solar radiation and precipitation, digital maps of soil types, terrain (elevation contours), and satellite remote sensing images of vegetation and land cover patterns. Preprocessing uses the spatial data inputs to break up the landscape into a hierarchy of watersheds of different sizes, and a set of "patches" within the watersheds that are used as the basic simulation units. Each of the landscape simulation units is modeled in parallel, with water runoff then sequentially routed towards the watershed outlet.

The model is currently written as a series of subroutines with a set of subroutines simulating each major process (e.g. photosynthesis, evaporation, soil water flow, nutrient cycling) and a set that control, organize and combine results from each process subroutine. Output includes time series of stream flow, evaporation, soil water content and other variables that can be aggregated to the full watershed from each simulation unit, or mapped at time slices for the full landscape (as surfaces) at the level of each unit. One area we would like to have work done in is in animation of these time stepped surfaces.

There are (at least) two projects that could be carried out: