Southwest Biological Science Center

Hydrology and Geomorphology

Filter Total Items: 25
Date published: December 30, 2016

Southwestern Riparian Zones, Tamarisk Plants, and the Tamarisk Beetle

Introductions of bio-control beetles (genus Diorhabda) are causing defoliation and dieback of exotic Tamarix spp. in riparian zones across the western U.S., yet the factors that determine the plant communities that follow Tamarix decline are poorly understood. In particular, Tamarix-dominated soils are often higher in nutrients, organic matter, and salts than nearby soils, and these soil...

Date published: December 22, 2016
Status: Active

Connectivity of Sand Resources Along the Colorado River in Grand Canyon

We study the links among different geomorphic processes that affect river valley landscapes in the Colorado River downstream from Glen Canyon Dam, Arizona. Dam-released flows affect the deposition and retention of sandbars that serve as sources for other sand resources, such as windblown sand dunes, throughout the Colorado River ecosystem. The degree to which the landscapes are differentially...

Date published: December 20, 2016
Status: Active

Riparian Remote Sensing in the Colorado River and Grand Canyon Region

Riparian vegetation has increased dramatically along the Colorado River downstream of Glen Canyon Dam since the closure of the dam in 1963. The spatial patterns and temporal rates of vegetation increase occur due to changes in river hydrology, dam operations, and climate. The increase in vegetation, particularly onto otherwise bare sandbars, has impacted recreational, geomorphological,...

Date published: December 15, 2016
Status: Active

Ecohydrology and Climate Change in Drylands

Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. However, climate forecasts in most dryland regions, especially the southwest U.S., call for increasing aridity. Specifically, changing climate will alter soil water availability, which exerts dominant control over ecosystem structure and function in water-limited, dryland ecosystems.  This research...

Contacts: John B Bradford
Date published: December 13, 2016

Measuring Water Requirements Of Riparian Regions in the Southwestern U.S. Compared with Drylands in Australia

Floodplain red gum forests are sites of high biodiversity in arid regions of south Australia. They depend on periodic floods from rivers, but dams and diversions have reduced flood frequencies, leading to deterioration of the trees. We determined the water requirements of red gum trees so environmental flows can be used to restore and maintain the forests. We used measurements of transpiration...

Contacts: Pamela Nagler
Date published: December 13, 2016

Using Imagery to Monitor Riparian and Upland Vegetation Along the San Pedro River, Arizona

The Upper San Pedro River is one of the few remaining undammed rivers that maintain a vibrant riparian ecosystem in the southwest. However, its riparian forest is threatened by diminishing groundwater and surface water inputs, due to either changes in watershed characteristics such as changes in riparian and upland vegetation, or human activities such as regional groundwater pumping. We used...

Contacts: Pamela Nagler
Date published: December 12, 2016
Status: Active

Suspended-Sediment Transport Dynamics of the Rio Grande/Rio Bravo

The Rio Grande/Rio Bravo (hereafter referred to as the Rio Grande) in the Big Bend region of Texas, USA, and Chihuahua, and Coahuila, MX has substantially narrowed since the early 1900s. This narrowing has been caused by the construction and operation of dams and irrigation diversions in upstream reaches of the Rio Grande in the U.S. and the Rio Conchos in Mexico that has reduced mean and peak...

Date published: December 9, 2016
Status: Active

RAMPS: Restoration Assessment & Monitoring Program for the Southwest

The Restoration Assessment and Monitoring Program for the Southwest (RAMPS) seeks to assist U.S. Department of the Interior (DOI) and other land management agencies in developing successful techniques for improving land condition in dryland ecosystems of the southwestern United States. Invasion by non-native species, wildfire, drought, and other disturbances are growing...

Date published: December 8, 2016
Status: Active

Grand Canyon Sandbar Monitoring

Since the completion of Glen Canyon Dam in 1963, the amount of sand supplied to Grand Canyon National Park has been reduced by more than 90 percent. The Paria River, a tributary to the Colorado River 15 miles downstream from the dam, is now the single most important supplier of sand to the Colorado River within the Park. This large reduction in sand supply has resulted in substantial decrease...

Contacts: Paul Grams, Ph.D., Robert Tusso, Keith A Kohl, Joseph E. Hazel, Jr., Daniel Buscombe, Matt Kaplinski
Date published: December 8, 2016
Status: Active

Adaptive Management

In 1996, the Secretary of the Interior signed a formal decision altering the historical flows from Glen Canyon Dam and establishing the Glen Canyon Dam Adaptive Management Program (GCDAMP). In the context of the management of Glen Canyon Dam, adaptive management was selected to create a process whereby “the effects of dam operations on downstream resources would be assessed and the results of...

Date published: December 7, 2016
Status: Active

Effects of Nonnative Vegetation Management

The Rio Grande/Rio Bravo (hereafter referred to as the Rio Grande) in the Big Bend region of Texas, USA, and Chihuahua, and Coahuila, MX has substantially narrowed since the early 1900s. This narrowing has been exacerbated by the widespread establishment of non-native giant cane (Arundo donax) and tamarisk (Tamarix spp.), both of which help trap sediment and protect banks from natural...

Date published: December 6, 2016
Status: Active

Big Sagebrush Ecosystem Response to Climate & Disturbance

Big sagebrush ecosystems are a major component of landscapes in the western U.S. and provide vital habitat to a wide array of wildlife species.  However, big sagebrush ecosystems have been dramatically impacted by disturbances in the past several decades. This collaborative research between USGS and the University of Wyoming focuses on understanding how climatic and soil conditions influence...

Contacts: John B Bradford