Unified Interior Regions

As part of the assessment of the binational San Pedro aquifer, the effects of urbanization on runoff in ephemeral streams was studied. Ephemeral streams are those that flow in response to precipitation. Runoff in tributaries to the San Pedro River is important in understanding the water budget of the river. In addition, in arid watersheds such as the San Pedro, flow in

Exploring the colorful southern Colorado Plateau in 3-D

By Philip Stoffer, Geologist

Take a colorful tour with the help of 3-D photography through some of the region's highlights:

• A plethora of parklands- Petrified Forest, Chaco Canyon, Wupatki, Grand Canyon
• High desert climate changes, past, present, and

Drilling for mineral resources near Canyonlands National Park, Utah

Climate change combined with overlapping high-intensity land uses are likely to create conditions detrimental to the recreation economy, wildlife habitat, water availability and other resources in hyper-arid landscapes, or drylands, in the future, according to a paper published in Ecosphere

More mesquite were visible, and prickly pear had replaced cholla as the dominant cacti. (Mitchel P. McClaran).

Two ranging poles were placed near the positions of two sets of saguaros in order to determine their heights, and hence approximate ages. Most were established in the 1890s, after livestock grazing and the removal of fine fuels had begun in the area. Several small saguaros have become established since the fire; one is to the left of the left-hand ranging pole,

USGS employees measuring flood flows on Rillito River in Tucson, Arizona.

USGS employees taking flood measurements using an Acoustic Doppler Current Profiler.

Measuring floods in Tucson, AZ 2006.

By Floyd Gray, Geologist

• Natural systems-water, geology, and wildlife-tend to cross the 1,900- mile-long arbitrary political border between Mexico and the U.S.
• Rapid population growth on the U.S. side and in Mexican border cities is creating a variety of environmental, ecological, and human health problems
• The San Pedro River

Large-scale poster describing USGS work.

USGS scientists needed a better way to measure river sand in the Grand Canyon. Traditionally, scientists used a bucket to get about 75 sand samples on each trip, which were analyzed weeks later in a lab.

To measure more locations and to speed up the analysis, we developed the Flying Eyeball underwater microscope.

Here, a U.S. Geological Survey (USGS) hydrographer is collecting a suspended-sediment water sample from the Little Colorado River, a kilometer upstream from the Little Colorado River, Grand Canyon, Arizona, USA. To gain knowledge of the suspended-sediment characteristics of the entire river (water quality can vary greatly across a river), suspended-sediment water samples