Coupling the precipitation runoff modeling system with a landscape ecosystem simulation

Considering the complex relationship of vegetative and hydrologic interacti ons across landscapes is an essential component when modeling hydrologic re sponse in upland watersheds. An approach for assessing vegetative and hydro logic condition of a watershed in response to natural processes and human-c aused treatments may provide resource managers with a useful tool for ecosy stem management. SIMPPLLE (SIMulating vegetative Patterns and Processes at Landscape ScaLEs) simulates vegetative change over time on forested landsca pes, but fails to address the consequences of vegetative and hydrologic int eractions. It falls short of capturing the complexity of landscape change. The purpose of this study is to provide the basis for a hydrologic componen t by proposing a hydrologic model that, when linked with SIMPPLLE, will sim ulate plausible hydrologic response to vegetation manipulation. The Precipitation Run-off Modeling System (PRMS) is a deterministic, distri buted-parameter water yield model that quantifies changes in hydrologic res ponse with respect to landscape manipulation. Using SIMPPLLE generated data , PRMS was run on the Sweathouse Creek watershed in western Montana to simu late vegetation and hydrologic response changes under a variety of manageme nt scenarios and meteorological conditions. Lack of continuous streamflow d ata precluded quantitative analysis and hence a qualitative model. performa nce assessment was necessary. Results show that PRMS provides plausible wat er yield outputs in response to landscape vegetation changes modeled by SIM PPLLE. The ability of PRMS to assess hydrologic response either on landscap e or much finer scale provides enhanced flexibility and utility to the syst em.