Water Resources Research Act Program

Details for Project ID 2010CO226B

Paleohydrology of the Lower Colorado River

Institute: Colorado
Year Established: 2010 Start Date: 2010-03-01 End Date: 2012-02-29
Total Federal Funds: $59,199 Total Non-Federal Funds: $14,432

Principal Investigators: Rajagopalan Balaji

Abstract: The State of Colorado draws a substantial portion of its water supply from the Colorado River. The reliability of this supply is a function of natural hydrologic variability, upon which anticipated changes in future climate will be superimposed. Thus, it is extremely important to understand the range of this natural variability in the basin streamflows so as to obtain a robust estimate of the water supply risk and consequently, devise effective management and planning strategies. Observed flow data that are limited in time (~100 years) cannot provide the full range of variability, even with stochastic models built on them. Paleohydrologic reconstructions of annual flow using tree rings, however, provide much longer (500-1000+ years) records of past natural variability, and thus a much richer sampling of potential flow sequences, including severe and sustained droughts of greatest concern to water resource managers. Such reconstructions are available for the combined Upper Colorado River basin flows, but there is no equivalent dataset for the Lower Basin. In this research we propose to develop a paleohydrologic reconstruction of the total Lower Basin streamflow. We will use all the existing tree-ring data and naturalized streamflow records, with a suite of statistical methods. The reconstructions from the different methods will be combined to provide an �ensemble� of flows in each year, thus providing an effective characterization of the uncertainty. A rich variety of streamflow ensembles will be generated for the entire basin using this and existing reconstructions for the Upper Basin to explore the basin-wide water supply risk, focusing on implications for the water resources of the State of Colorado.