Preparing for rainy days
When designing any kind of structure, understanding how water accumulates and flows is crucial. Highways, runways, housing developments, and other infrastructure are designed to avoid service interruptions and damage from precipitation events. Water conveyance structures (from small culverts to large dams) are designed to hold and pass precipitation flows. Thus the more accurate and comprehensive the precipitation frequency data is, the better the designs.
Many federal, state, local, and private agencies are updating and expanding these precipitation frequency estimates. Previous frequency estimates compiled in the 1960s and 70s were limited to 10 day durations and 100 year return periods. This effort includes the data from tens of thousands of rainfall stations for the last 40 years to bring the estimates up to date and extend parameters. The study processes data to determine patterns and annual all-season precipitation frequencies for durations from 5 minutes to 60 days for return periods from 2 to 1,000 years.
The National Weather Service leads this multi-agency action that includes Reclamation's Science and Technology Program. Progress reports and data are available at <http://www.nws.noaa.gov/oh/hdsc/current-projects> The data for the Southwest area will be published in NOAA Atlas 14–National Precipitation Frequency Atlas in 2003, with more areas published over the next 5 years.
The U.S. Bureau of Reclamation in particular needs updated information to evaluate facility safety and operations. Developing methods to better estimate and understand flood events is especialy important to provide the maximum storage and water deliveries while maintaining appropriate levels of safety for extreme flood events. Thus, Reclamation's Science and Technology Program is developing the depth-area relationships (rainfall frequency values distributed over a watershed). These relationships will help show how precipitation is distributed over an area to determine water flows. These data are crucial in preparing maps to understand precipitation distribution and water movements over a wide area over time. Understanding water patterns over drainages and watershed will provide invaluable insights needed to effectively manage water related resources and facilities. Beating what is eating away our infrastructure
In the United States, total corrosion costs are estimated at $552 billion dollars a year–about 6 percent of the Gross National Product, according to a 2002 congressional study. Corrosion -- materials deteriorating as they interact with the environment-- weakens metals, plastics, and even concrete. To keep its infrastructure healthy, Reclamation's Science and Technology investigates corrosion-related problems and mitigation methods. This research and the subsequent technology transfer increase the awareness of corrosion and associated costs, demonstrate sound corrosion management techniques, and improve corrosion technology and its use. The end result is the improved dependability and lower life cycle costs of Reclamation's infrastructure.
One way to stop corrosion on buried or submerged metallic structures is cathodic protection. When electrical current leaves a structure and goes into the soil or water it causes corrosion (or rust) on the structure. Cathodic protection redirects the current to flow onto the structure, thus stopping the corrosion. Cathodic protection could extend the life of structures indefinitely which would have suffered premature deterioration due to corrosion.
Reclamation is currently evaluating methods to accurately evaluate levels of cathodic protection on buried pipelines that share the right-of-way with power lines. These lines can induce an electrical signal on the pipeline. Reclamation has used potentially controlled rectifiers (a type of rectifier used for a impress current cathodic protection system) on these pipelines. However, the electrical signal can affect the rectifier's operations. The Science and Technology Program research examines these signals' effects and methods to remove these signals. As these cathodic protection systems are used throughout the United States, others with buried pipelines can benefit from this research.
Reclamation is forming research partnerships with organizations interested in this and other ways to address corrosion. Please contact the Science and Technology Program