Channel Reliability Study, Willapa Bay, Washington

The shifting channels at the entrance to Willapa Bay make bar navigation unreliable, and the local port is having difficulty attracting commercial users. The Seattle District requested the U.S.Army Engineer Research and Development Center (ERDC) conduct a study to determine the technical feasibility of maintaining a reliable channel (28-ft depth including advance dredging and over-dredging allowance) over the entrance bar and into Willapa Bay. The strong wave and tidal current environment require innovative approaches to sustain a reliable channel via dredging and adjusting to relatively long-term cycles of channel morphology. This paper reviews the channel engineering and morphological analysis required to determine viable alternatives that might provide a reliable channel.