K2-O2 (KINEROS-Opus) SPATIALLY BASED WATERSHED HYDROLOGIC AND BIOGEOCHEMICAL MODEL

Recently a new combined hydrologic and biogeochemical model has been developed. K2-O2 is a comprehensive, spatially-distributed watershed model designed to simulate the hydrologic and biogeochemical processes of small- to medium-sized watersheds. K2-O2 is a combination of KINEROS2, an event-based Kinematic Runoff and Erosion Model, and Opus2, a time-continuous soil moisture and nutrient cycling model. K2-O2 is able to simulate long-term effects due to hydrologic changes and watershed management practices allowing for prediction future ecosystem behaviors. The range of simulations that can be carried out by K2-O2 include: runoff, sediment transport, nutrient cycling (nitrogen, phosphorus and carbon), water quality and chemical runoff. K2-O2 is undergoing rigorous testing using data from two hydrologically distinct watersheds verification and validation: the USDA-ARS (United States Department of Agriculture-Agricultural Research Service) Watkinsville Experimental Watershed P-3 catchment in Watkinsville Georgia and the USDA-ARS Walnut Gulch Experimental Watershed Lucky Hills 104 catchment located near Tombstone, Arizona. P-3 is a cultivated agricultural catchment characterized by a humid sub-tropical climate that experiences a range of management practices. The LH-104 is a natural catchment characterized by a semi-arid desert climate and dominated by desert shrubs. Verification of water, nitrogen and phosphorus submodels were conducted using mass balance calculations. Validation of the hydrologic submodel was conducted using field data measured at each watershed. K2-O2 produced reasonable simulations of the hydrology and nutrient cycling. K2-O2 will continue to undergo testing, verification and validation of hydrologic and biogeochemical submodels with observations from these and other experimental watersheds. K2-O2 will provide watershed managers and natural resource planners with a tool to assess the spatial distribution of hydrological and biogeochemical processes for present and future management of watersheds.