Real Time Currents in the Harbors of the Great Lakes - A Pilot Project

NOAA´s National Ocean Service´s Center for Operational Oceanographic Products and Services (CO-OPS) is responsible for ensuring safe maritime navigation and supporting efficient water-borne commerce. CO-OPS oceanographic and environmental data sets also benefit the National Weather Service, coastal zone managers, and the engineering and surveying communities. In 2006, a new pilot project was introduced and implemented in the Great Lakes to measure currents in real time, horizontally across the Cuyahoga River in Cleveland, and the Maumee River in Toledo, Ohio. This project provides CO-OPS with a variety of new opportunities to expand the National Current Observation Program (NCOP) to the freshwater environment; to enhance partnerships with the Great Lakes shipping community, City of Cleveland, private industry, and federal agencies; and to test a new platform design for a horizontal acoustic Doppler current profiler developed by the U.S. Army Corps of Engineers, Detroit District. The pilots of the Lake Carriers and Lakes Pilots Associations requested assistance with navigating the Cuyahoga and Maumee Rivers where winds affect their transit through narrow bridge spans and around sharp bends. The real-time current data provides the pilots with advanced knowledge of the conditions to be expected while in transit, and thus affording them the opportunity to load the vessel accordingly before committing to the river. The pilots identified the narrowest channel of the Cuyahoga River at the Center Street swing bridge in Cleveland, Ohio as a place where real time current measurements would provide them with a worst-case scenario of current speed prior to entering the river. Another area identified by the pilots occurs as vessels inbound from Lake Erie must transit through a narrow span of a railroad swing bridge on the Maumee River as they approach the Archer Daniels Midland (ADM) pier to offload their grain. Access to the latest six minute record of current speed and direc- tion at ADM represents conditions just beyond the bridge spans and this allows the pilot to plan an approach through this area. The real time data (every 6 minutes) can be accessed by the public through the web on the Great Lakes Online web page (http://glakesonline.nos.noaa.gov/moncurrent.html). The data are also available via NOAA´s Interactive Voice Response System at 301-713-9596. Data collection of current speed and direction started in July 2006 and continues to the present at both sites. A persistent pattern has been noted at the Cuyahoga River site where a seiche oscillates approximately every 1.5 hours unless sustained winds compromise the current flow. Flow is either inbound or outbound (towards the lake) at approximately 0.8 knots. There isn´t a real-time water level station upstream of the Center Street swing bridge on the Cuyahoga River so an examination of the variation in volume flow from the downstream NOS water level station located in Lake Erie cannot be simultaneously compared to the current data. A significant feature of the acoustic signal attenuation was noted at the ADM pier last winter when water temperatures approached 32 degrees Fahrenheit. Normal maximum profiling ranges diminished as the temperature dropped and approached freezing. In addition, side lobe interference also increased with the drop in temperature. Other seasonal changes in speed, temperature, and spikes in the data due to wind events are observed as well. This pilot project may include a third horizontal current meter site at the head of the St. Clair River in the vicinity of the Blue Water Bridge in Port Huron, Michigan in late 2007. Since this project is termed a pilot project, the addition of other current meter sites is dependent on follow-on funding from the US Congress or other sources.