Demeter – A Land Use and Land Cover Change Disaggregation Model
Land use and land cover have a strong influence on the evolution of the Earth system, but tools for downscaling and propagating these changes across different modeling platforms are limited. Demeter, an open-source model developed by the U.S. Department of Energy’s Pacific Northwest National Laboratory, is designed to translate regional projections of future land use from integrated human-Earth system models into high-resolution representations of time-evolving land cover suitable for input into complex Earth system and global hydrologic models.
Demeter provides a flexible and repeatable methodology to connect models that produce or require land use and land cover data at varying scales. Demeter is a well-documented, open-source community model that uses a common scale-independent methodology to advance the science of multi-sector, multi-scale dynamics research.
Changes in land use and land cover, such as an increase in the fraction of the land surface dedicated to specific agricultural crops, have a profound influence on land surface hydrology and biogeochemistry. Researchers developed Demeter, an open-source Python package, to disaggregate projections of future land allocations generated by the Global Change Assessment Model (GCAM), which accounts for a wide range of human-Earth system interactions. Earth system models cannot use this land allocation information directly because they need to know exactly how and where these land use changes translate into specific land cover modifications. For example, GCAM might project a 40 percent increase in corn production in Iowa, but an Earth system model needs to know exactly where that increase in production will occur on the landscape to calculate its influence on regional hydrology and land-atmosphere exchanges. Traditionally, this translation of projected regional land use into spatially explicit land cover information has required a number of manual steps. However, the process is inefficient and can introduce errors or mask uncertainties.
Demeter seamlessly generates land use and land cover change products in a variety of formats and resolutions commonly used by Earth system and hydrologic models. It also allows the user to easily modify a number of assumptions that control how regional changes in land use get translated into land cover information. Publicly available via the GitHub code repository, Demeter is being used to generate multiple future land use and land cover change scenarios and to explore the uncertainties associated with different downscaling assumptions.