Streamflows in late spring and summer have declined over the last century in the western US and mean annual streamflow is projected to decrease by six to 25% over the next 100 years. In arid and semi-arid regions of the western US, it is likely that some perennial streams will shift to intermittent flow regimes in response to climate-driven changes in timing and magnitude of precipitation, runoff, and evapotranspiration. We propose to address the following two research question: (1) how will small stream (1st-3rd order) low flow hydrology be impacted by predicted longer, drier summers in the Upper Colorado River Basin under climate change and (2) in tum, what will be the resulting impacts on riparian plant communities? To address these [...]
Summary
Streamflows in late spring and summer have declined over the last century in the western US and mean annual streamflow is projected to decrease by six to 25% over the next 100 years. In arid and semi-arid regions of the western US, it is likely that some perennial streams will shift to intermittent flow regimes in response to climate-driven changes in timing and magnitude of precipitation, runoff, and evapotranspiration. We propose to address the following two research
question: (1) how will small stream (1st-3rd order) low flow hydrology be impacted by predicted longer, drier summers in the Upper Colorado River Basin under climate change and (2) in tum, what will be the resulting impacts on riparian plant communities? To address these research questions we will undertake two major tasks: (1) model stream low flow metrics on ungaged streams in the UCRB and (2) sample riparian plant communities along a hydrologic gradient (perennial to intermittent) to develop statistical relationships between flow parameters and biotic responses that can eventually be used to help predict biotic changes under climate change-driven stream drying. Our proposed study directly addresses Southern Rockies LCC Project Task Areas A and B by projecting changes to surface water low flows and changes to riparian ecosystems, including distribution of invasive riparian plants, under future climate changes in the Southern Rockies LCC region. Task 1 will result in GIS data layers and maps for streams in the UCRB indicating how stream low flows may change under future climate scenarios that will be accessible on an interactive website. Task 2 will result in statistical models that relate flow parameters to riparian vegetation composition. Final products will include annual progress reports, a final report, a peer-reviewed manuscript, a final presentation, and an informational, interactive website accessible to land and water managers. The tasks included in this research will be carried out over 2 years, completed by September 2013.
