Modeling Vernal Pool Hydroperiod Over Space and TimeEPA Grant Number: U915753
Title: Modeling Vernal Pool Hydroperiod Over Space and Time
Investigators: Pyke, Christopher R.
Institution: University of California - Santa Barbara
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2000 through September 1, 2003
Project Amount: $80,926
RFA: STAR Graduate Fellowships (2000) RFA Text | Recipients Lists
Research Category: Fellowship - Social Sciences , Academic Fellowships , Environmental Justice
It is hypothesized that spatial and temporal variability in vernal pool hydroperiod is an important factor in wetland restoration, site management, and regional conservation planning. This project will: (1) develop a process-based model for the prediction of pool hydroperiod; (2) describe patterns of spatial and temporal variability in vernal pool hydroperiod based on current and historical climatic data; and (3) predict the potential impacts of climate change on vernal pool plant and invertebrate communities.
The project will proceed in three parts: (1) developing a process-based model for vernal pool hydroperiod; (2) applying the model to map patterns of hydroperiod across the ecoregion; and (3) applying the model to project changes in pool hydroperiod associated with climate change. The first stage currently is underway. The research involves both the intensive monitoring of 10 local vernal pools and the extensive sampling of basin morphology, soils, and vegetation across the ecoregion. The goal is to develop a climatically driven pool-filling model that predicts the onset, duration, and depth of pool inundation as a function of climatic inputs, including soil (available water-holding capacity), vegetation cover, and basin morphology. Field data will be integrated with existing geospatial information to estimate the statistical responses of pool landscapes based on the statistical distribution of model input parameters. Pool landscapes will be defined using the concept of an "Integrated Terrain Unit" that combines climate, soils, and geology in identifying discrete landscape units with the potential for similar patterns of hydrologic behavior. Based on the variance observed within terrain units, field sampling will be used to characterize the statistical distribution of model parameters within each unit. Following validation, the hydroperiod model will initially be run in a hind-casting mode, using climate data archived in the National Climatic Data Center and collected through the California Department of Water Resources (CIMIS automated weather stations). Station data vary across the ecoregion, but high quality data are available at least since 1946 for more locations.
The results of this modeling will provide an initial estimate of spatial and temporal variability during the last 50 years. Finally, the model will be used in a forecasting mode to evaluate the potential implications of climate change on pool hydrology under a variety of scenarios. Predictions for Southern California include the potential for changes in the timing of annual precipitation and a shift toward more intense precipitation events. Studies have shown that these kinds of changes may result in competitive shifts in pool plants and changes in species composition and diversity among invertebrates. Model outputs will be compared with the ecological literature to create a matrix of possible future conditions for vernal pools across Southern California.