Submitted to: Ecological Modelling
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2001
Publication Date: 3/20/2001
Citation: Pierson, Jr., F.B., Carlson, D.H., Spaeth, K.E., 2001. A process-based hydrology submodel dynamically linked to the plant component of the simulation of production and utilization on rangelands SPUR model. Ecological Modelling 141:241-260.
Interpretive Summary: Rangelands are a complex system comprising vegetation, soils, animals, and climate. It is difficult to evaluate hydrology, and management impacts on hydrology, on these complex systems without using process- based models (i.e., models that represent how elements of the system interact and affect a process through space and over time). The original empirical hydrology submodel in SPUR2.4 (TX Agr. Exp. Sta.)was replaced with an infiltration-based submodel from WEPP (Water Erosion Prediction Project, USDA-ARS, 1995). The revised model (SPUR 2000) was tested using data from Idaho sagebrush rangeland. SPUR 2000 did a better job of predicting individual storm runoff, and modeled runoff and erosion estimates were influenced more by vegetation as compared to the original model. This model revision will provide more accurate short-term predictions of runoff from thunderstorms and will assist rangeland managers in assessing how management practices will impact the hydrology and erosion potential of rangeland sites over time. .
Technical Abstract: Process-based models designed to evaluate rangeland hydrology must include sophisticated plant and animal components that simulate changes in vegetati over space and through time. An infiltration-based submodel similar to that used in WEPP (USDA-ARS) was dynamically linked to the SPUR2.4 rangeland ecosystem model (TX Agr. Exp. Sta.) To provide the framework for future model enhancementand investigation of the impacts of management on the ran ecosystem. Model description and documentation of model modifications are presented for SPUR 2000. A sensitivity analysis and initial test of SPUR 2000 were performed using rainfall simulation plot and micro- watershed data from Idaho sagebrush rangeland. The sensitivity analysis showed improved sensitivity of runoff and erosion to various vegetation parameters. The long-term simulations demonstrated good representation of soil water content, peak standing crop, and evapotranspiration. SPUR 2000 did a better job of predicting individual thunderstorm runoff events, and estimated 15-year runoff within 12 percent compared to SPUR2.4, which grossly overestimated runoff. Neither model accurately predicted sediment loss, but predicted values did demonstrate the relatively small amount of erosion that occurs from these rangelands. Neither model accurately predicted sediment loss, but predicted values did demonstrate the relatively small amount of erosion that occurs from these rangelands. Additional research needs to explore the degree of influence that vegetation has on infiltration and runoff, and how it varies for different plant communities.