Collaborative Research: P2C2--Where Has the water Gone? Results from a Watershed Model with Dendroclimatic Inputs

点击翻译按钮获取中文摘要

This project aims to determine the past behavior of river discharge, evapotranspiration, and snow-water equivalent by applying a combination of multiple tree-ring variables and water balance modeling. This research is part of an effort to improve the understanding of runoff from about one-third of the 200 largest rivers which has changed significantly since the 1950s yet lacks context for much longer (century-scale) information on seasonal runoff variability for individual watersheds that could help constrain future climate model projections.Specifically, the researchers aim to determine the past behavior of river discharge, evapotranspiration, and snow-water equivalent by applying a combination of multiple tree-ring variables and water balance modeling. Seasonal inputs, i.e. precipitation and air temperature, will be derived from multi-proxy tree-ring chronologies (early- and late-wood width, blue intensity, and wood anatomy measurements) in the western U.S. The field study design will update tree-ring chronologies that are part of the ITRDB (International Tree-Ring Data Bank) and will combine classic sampling methods with modern standardization tools. Compared with statistics-only reconstructions, the use of a watershed model may provide a way to perform sensitivity studies that improve the estimation of uncertainty in the extended records, in particular with regard to landscape and vegetation factors influencing infiltration and runoff efficiency (ratio of runoff to precipitation). A proof-of-concept study is included in the project to clarify how our monthly water balance model can be calibrated and run using seasonal instrumental and proxy records of climate. Accuracy of discharge reconstructions by the water-balance approach will be compared with that of reconstructions by the conventional approach of regression of gaged discharge on tree-ring data. The study area is the combined Truckee/Carson River Basin (Nevada and California), which embodies many of the water resources issues currently confronting managers and planners in the western U.S. Drought characteristics of this basin will be examined to place recent droughts in a long-term context. Spatial aspects of drought variability related to large-scale climatological drivers will be evaluated by comparing the new reconstructions with existing ones for other western rivers. The project also includes development of an interactive online mapping tool for use by resource managers, planners, and the general public in exploring the history of local and regional hydroclimate.The potential Broader Impacts (B.I.) include data useful for improved management of water and forest resources in the Truckee/Carson Basin and by extension in the Sierra Nevada, a critical mountain range for freshwater resources in the western United States. The project will support two graduate students directly engaged in the project as well as several undergraduate students. The project will also develop an online mapping tool that K-12 students who participate in UA Tree-Ring Lab's outreach program would be able to use.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.