Accounting for Watershed Behavior in a Changing Climate
Researchers have long been challenged with how to provide credible simulations of streamflow given different climate change scenarios. This challenge extends to the development of meaningful estimates of uncertainty and to historical observations for model conditioning. Ultimately, methods must account for the differences in how watersheds ‘behave’ if located in a different climate for long periods of time. DOE researchers developed a new Bayesian framework that uses a trading-space-for-time methodology, an idea adapted from seismic hazard modeling. The approach builds from similarities between spatial gradients of hydrologic response at the basin scale and temporal gradients (if a basin is placed in a different climatic regime). The new method is tested in five U.S. watersheds located in historically different climates using synthetic climate scenarios generated by increasing mean temperature by up to 8°C and changing mean precipitation by -30% to +40% from their historical values. Depending on the aridity of the watershed, streamflow projections using adjusted parameters became significantly different from those using historically calibrated parameters if precipitation change exceeded -10% or +20%. In general, the trading-space-for-time approach resulted in a stronger watershed response to climate change for both high- and low-flow conditions. The approach is independent of the hydrological model used and can be used directly (without the need for a hydrologic model) in integrated assessment models.
Singh, R., T. Wagener, et al. 2011. “A Trading-Space-for-Time Approach to Probabilistic Continuous Streamflow Predictions in a Changing Climate: Accounting for Changing Watershed Behavior,” Hydrology and Earth System Sciences 15, 3591-3603, DOI: 10.5194/hess-15-3591-2011.