Proceedings Of The Marine

SUM 2015

Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.

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32 Proceedings Summer 2015 Today's Port of Portland is also involved in aviation, indus- trial, and marine operations; within the latter, river chan- nel maintenance remains a top priority. In fact, the Port of Portland owns and operates the dredge Oregon, which is devoted to Columbia River channel maintenance, under contract to the U.S. Army Corps of Engineers. Close coor- dination among maritime stakeholders, including river and bar pilots, the U.S. Coast Guard, the U.S. Army Corps of Engineers, and lower Columbia River port personnel, ensures ships can transit through the river channel safely, without delay. Challenges The challenges to channel maintenance are many and can depend on varying river fows, tidal infuence, and complex dam release fow rates. Portland's tide range is usually on the order of two feet; this increases to about eight feet near the river's mouth. Minimum water levels (low tide) at the Portland/Vancouver terminals are typically about six feet above Columbia River Datum (see sidebar), during high fow months (December to May/June), and two feet above datum from July to November. River current is typically one to two knots on the food (com- ing from the sea to the shore ) and three to four knots on the ebb (coming from shore and returning to the sea), but can on occasion reach six knots on the ebb in the lower river. In this active environment, accurate river level forecasting tools and navigation systems are crucial. Solutions To this end, the LOADMAX system and the Physical Oceano- graphic Real-Time System (PORTS ® ), form a public informa- tion acquisition and dissemination technology partnership between the National Oceanic and Atmospheric Admin- istration (NOAA) and the Port of Portland. LOADMAX consists of seven computer-connected PORTS gauges along the lower Columbia channel, from river mile 17 at Astoria, Oregon, to river mile 106.5 at Vancouver, Washington. These Columbia River ports in Portland, St. Helens, and Astoria, Oregon; along with Vancouver, Kalama, Longview, and Woodland, in Washington state, comprise important eco- nomic gateways for shipping cargo into and out of the U.S. West Coast. About 60 million tons of oceangoing cargo move up and down the Columbia River in approximately 4,000 ship transits each year. 1 The Columbia River Helping shape 21 st century navigation. by Mr. fred Myer Senior Waterways Planner Port of Portland Stakeholders' Perspective Columbia River Datum Users developed the Columbia River Datum (CRD) to defne an accurate baseline in this dynamic river system. CRD, or "zero gauge," is a solution to the problem of a 103-mile channel running down an imperfect inclined plane. CRD provides a worst-case zero state. Simply stated, the Columbia River Datum is the lowest river level that can be expected in an average year. It was established in the 1920s, when the U.S. Army Corps of Engineers sent teams of surveyors into the feld to measure the low water profle at a low fow of approx- imately 80,000 cubic feet per second (cfs). Natural low fows rarely reach that level in the river and, with the advent of upstream storage reservoirs, it is even more of a rarity. Since the annual combined fow of the Columbia and Willamette Rivers is approximately 227,000 cfs, water levels in the river above Westport, Oregon, are likely to be above zero datum for most of the year. Fortunately, the river sees negative CRD numbers for only 10 to 30 hours a year. At all other times, there is some amount of water available above this estab- lished baseline. Tracking this water level accurately is critical fuel for the economic engine of Columbia River commerce.

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