Theodore "Teo" Melis, Ph.D. (Former Employee)

No abstract available.

Executive Summary Glen Canyon Dam is located in the lower reaches of Glen Canyon National Recreation Area on the Colorado River, approximately 15 miles upriver from Grand Canyon National Park (fig. 1). In 1992, Congress passed and the President signed into law the Grand Canyon Protection Act (GCPA; title XVIII, sec. 1801?1809, of Public Law 102-575), which seeks ?to protect, mitigate...

Large dams have the potential to dramatically alter the flow regime, geomorphology, and aquatic ecosystem of downstream river reaches. Development of flow release regimes in order to meet multiple objectives is a challenge facing dam operators, resource managers, and scientists. Herein, we review previous work and present new analyses related to the effects of Glen Canyon Dam on the...

Grand Canyon National Park lies approximately 25 km (15 mi) down-river from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border in Glen Canyon National Recreation Area. Before the dam began to regulate the Colorado River in 1963, the river carried such large quantities of red sediment, for which the Southwest is famous, that the Spanish named the...

For more than a century, studies of sedimentology and sediment transport have measured bed-sediment grain size by collecting samples and transporting them back to the laboratory for grain-size analysis. This process is slow and expensive. Moreover, most sampling systems are not selective enough to sample only the surficial grains that interact with the flow; samples typically include...

No abstract available.

For more than a century, studies of sedimentology and sediment transport have measured bed-sediment grain size by collecting samples and transporting them back to the lab for grain-size analysis. This process is slow and expensive. Moreover, most sampling systems are not selective enough to sample only the surficial grains that interact with the flow; samples typically include sediment...

This report is an important milestone in the effort by the Secretary of the Interior to implement the Grand Canyon Protection Act of 1992 (GCPA; title XVIII, secs. 1801-1809, of Public Law 102-575), the most recent authorizing legislation for Federal efforts to protect resources downstream from Glen Canyon Dam. The chapters that follow are intended to provide decision makers and the...

Debris flows from 740 tributaries transport sediment into the Colorado River in Grand Canyon, Arizona, creating rapids that control its longitudinal profile. Debris flows mostly occur when runoff triggers failures in colluvium by a process termed “the fire hose effect.” Debris flows originate from a limited number of geologic strata, almost exclusively shales or other clay‐rich, fine...

The U.S. Geological Survey is evaluating potentially useful surrogate instruments and methods for inferring the physical characteristics of suspended sediments. Instruments operating on bulk acoustic, bulk and digital optic, laser, and pressure-differential technologies are being tested in riverine and laboratory settings for their usefulness to Federal agencies toward providing...

No abstract available.

No abstract available.