The Colorado River is a crucial water source for millions of people in the Southwest. Warming temperatures, clearly documented in climate records for the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Recent work has revealed that warming temperatures have played an increasingly important role over the past decades, both exacerbating droughts and dampening the effects of wet winters on high stream flows. Understanding and anticipating how warming temperatures will influence future water supply in the Colorado River basin is increasingly important for resource management, particularly in light of recent drought conditions. The overarching goals of this project are to better [...]
Summary
The Colorado River is a crucial water source for millions of people in the Southwest. Warming temperatures, clearly documented in climate records for the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Recent work has revealed that warming temperatures have played an increasingly important role over the past decades, both exacerbating droughts and dampening the effects of wet winters on high stream flows. Understanding and anticipating how warming temperatures will influence future water supply in the Colorado River basin is increasingly important for resource management, particularly in light of recent drought conditions.
The overarching goals of this project are to better understand the influence of temperature on Colorado River streamflow, particularly during droughts, and assist water managers in planning for future droughts. This work expands on a recently completed study, building on that project in two main ways. First, this project extends collaborative work between scientists and Colorado River basin water managers to investigate the range of potential drought conditions under early 21st century warming, using both recent and historical data. For example, with precipitation reconstructions from tree rings for the past 500 years, the team can use a simple hydrologic model to assess the impacts of the longest and most severe droughts of the past on the Colorado River under today’s warmer temperatures. With this information, the project team will contribute to a set of plausible scenarios of future drought that planners can use to help make resource-management decisions. Second, the project is more explicitly examining the drivers of Colorado River drought, with a focus on factors such as the phase of precipitation (rain vs. snow), the timing and rate of snowmelt, and evaporation rates. The project team will also begin to explore the ways that changing temperatures and streamflow might impact the ecological health of the upper Colorado River basin.
Click on title to download individual files attached to this item.
ColoradoRiver_AZ_USGS.jpg “Colorado River, USGS”
402.42 KB
image/jpeg
Purpose
Warming temperatures, clearly documented in instrumental records in the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Warmer temperatures result in less flow than might be anticipated, given the precipitation that has fallen. The goal of this project is to assist water managers in planning for future droughts in the Colorado River basin in two main ways. First, it addresses the need for future drought scenarios for planning. Natural climate variability, that has included droughts, will continue but with the added influence of warmer temperatures. Consequently, droughts of the past are not a reliable baseline for anticipating future drought and their impacts. However, droughts of the past plus warming temperatures can provide scenarios of plausible future droughts that could answer questions such as: “What would Colorado River flow look like if we have a 1950s-like drought today or in the next decade?” This perspective can be extended using reconstructions of precipitation from tree rings for the past 500 years, with warming, to assess the impacts of the longest and most severe droughts of the past five centuries on the Colorado River under today’s warmer temperatures. The second way this study will address the need for better drought information is to more closely examine just what it is about warming temperatures that may influence streamflow. We will use models of streamflow that allow an examination of the basin locations and/or levels of streamflow that may be most vulnerable to warming. This information will help water managers be prepared to anticipate how water resources will be impacted by the range of climatic conditions that are likely to occur in the future. Finally, this project will use similar methods to assess the ecological impacts of drought on the upper Colorado River basin.