Presentation Type

Poster

Abstract

Climate change may be producing an intensification of the global hydrologic cycle that may result in an increasing or decreasing precipitation trend over western Montana. Although direct detection of a small change in precipitation may be difficult, its effects in the streamflow record should be detectable and differentiable from other impacts. Theoretical calculations suggest that the effect of a precipitation trend on runoff is greater in the 25% wettest years than in the 25% driest years. This is the opposite of what is expected from other human impacts, such as water diversions or land-use change, which should have a greater effect on the 25% driest years. I test this hypothesis with a simulation study. I simulate precipitation data with an artificial trend over a 50 year period. Using the ECH2O watershed model to simulate runoff from an example watershed with my simulated precipitation data I study the trends of the selected streamflow percentiles. I compare the percentile trends to alternative scenarios in which precipitation is stationary but land use is changing. The behavior of the streamflow percentiles is compared to the theoretical calculations to confirm whether the effect of precipitation change is detectable and differentiable from other disturbances. My approach to this problem utilizes an advanced watershed model to test my hypothesis and generate knowledge about processes hard to observe in actual data. This paper provides a framework to analyze the streamflow record and infer whether streamflow change is due to changes in precipitation or in land use.

Category

Physical Sciences

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Apr 11th, 3:00 PM Apr 11th, 4:00 PM

Modeling Long-Term Streamflow Response to Precipitation Change Using an Ecohydrologic Model

Climate change may be producing an intensification of the global hydrologic cycle that may result in an increasing or decreasing precipitation trend over western Montana. Although direct detection of a small change in precipitation may be difficult, its effects in the streamflow record should be detectable and differentiable from other impacts. Theoretical calculations suggest that the effect of a precipitation trend on runoff is greater in the 25% wettest years than in the 25% driest years. This is the opposite of what is expected from other human impacts, such as water diversions or land-use change, which should have a greater effect on the 25% driest years. I test this hypothesis with a simulation study. I simulate precipitation data with an artificial trend over a 50 year period. Using the ECH2O watershed model to simulate runoff from an example watershed with my simulated precipitation data I study the trends of the selected streamflow percentiles. I compare the percentile trends to alternative scenarios in which precipitation is stationary but land use is changing. The behavior of the streamflow percentiles is compared to the theoretical calculations to confirm whether the effect of precipitation change is detectable and differentiable from other disturbances. My approach to this problem utilizes an advanced watershed model to test my hypothesis and generate knowledge about processes hard to observe in actual data. This paper provides a framework to analyze the streamflow record and infer whether streamflow change is due to changes in precipitation or in land use.