water

Instrumental record of Colorado River streamflows. The naturalized flow of the Colorado River has varied between 5.3 and 24.0 million acre-feet per year at Lees Ferry near Page, Arizona. Naturalized flow is an estimate of the River's flow that would occur in absence of human diversions or withdrawals. One acre-foot is equal to approximately 326,000 gallons.

This figure illustrates a relationship between water demand and Tucson's climate. Mostly notable is how demand drops as the summer monsoon begins. Maximum daily potable water demand (red) in Tucson Water utility’s service area (based on 2005-2007 data), and average daily precipitation at Tucson International Airport (blue).

Single-family water usage is a useful metric for evaluating how efficiently a community uses water.

Historic water-level declines in producing aquifers of the arid and semiarid southwestern United States. Water levels have recovered in some areas in response to reduced pumping, optimization, and other management measures. 60 meters is approximately 200 feet, 30 meters is approximately 100 feet, and 15 meters is approximately 50 feet.

The top graph shows the positive relationship between Annual frequency of large (>400 hectare) wildfires (bars) and average spring and summer temperatures (line) in Western U.S. forests. Using the same x-axis, the bottom graph shows the first principal component of the center timing of streamflow in snowmelt dominated streams (pink = early, white = average, blue = late).

Coastal and island tide-gauge data show that sea level rose by just under 20 cm between 1870 and 2001, with an average rise of 1.7 mm per year during the 20th century and with an increase in the rate of rise over this period. This is consistent with the geological data and the few long records of sea level from coastal tide gauges.

The global conveyor belt thermohaline circulation is driven primarily by the formation and sinking of deep water (from around 1500m to the Antarctic bottom water overlying the bottom of the ocean) in the Norwegian Sea. When the strength of the haline forcing increases due to excess precipitation, runoff, or ice melt the conveyor belt will weaken or even shut down.

Posted by Michelli Murphy | on October 15, 2008
Researchers are using tree-rings to reconstruct past Colorado River streamflow to see how common, and extreme, southwestern drought can be—information that is vital to water managers.

Posted by Stephen Miller | on September 23, 2008
Changes in the timing of spring snowmelt could have profound implications for aquatic species habitat in Arizona.