Applied Dendrohydrology on the Northern Great Plains: Limitations and Further Opportunities

Over the past three decades, the Tree-Ring Lab at the University of Regina has established a network of nearly 200 moisture sensitive tree-ring chronologies on the eastern slopes of the Rocky Mountains and across the northern Great Plains. The reconstructed paleohydrology of this sub-humid region informs our understanding of the hydroclimatic variability underlying shifts in the hydrological regime occurring in response to climate change. This presentation highlights various practical applications of our knowledge of the regional hydroclimate derived from tree rings, with an emphasis on the limitations and unique opportunities provided by dendrohydrology in support of water resources management and planning. Our reconstructions of streamflow, and other hydrological variables, are valued by water resource managers who recognize the uncertainties in the modeling of watershed hydrology and utility of long hydrological records for constraining model projections and distinguishing between natural variability and a signal of the regional expression of global climate change. The spatio-temporal resolution of our tree-ring records has improved by expanding the number of proxies, species and sites, and via the stochastic disaggregation of annual and seasonal reconstructions to weekly estimates. The applications have evolved from providing drought scenarios and analogues to proxy-model inter-comparison and evaluating model projections of future climate. Currently we are using the multi-decadal mode of variability embedded in tree-ring time series to improve 1) the forecasting of multi-year drought, and 2) the modeling of runoff in the pothole region of the northern plains, where a large amount of depressional storage has a strong influence on streamflow especially during prolonged periods of excess water and hydrological drought.