Dredging
People and goods have moved along coasts through most of human history. Good ports spawn cities as waterborne trade focuses economic activity in specific geographic locales. However, to carry more cargo at a reduced cost, ships have gotten bigger, in many
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Dredging
People and goods have moved along coasts through most of human his tory. Good ports spawn cities as waterborne trade focuses economic ac tivity in specific geographic locales. However, to carry more cargo at a reduced cost, ships have gotten bigger, in many cases outgrowing the har bors that used to accommodate them. As a result, dredging—removing sediment from the ocean floor—has become as much a part of shipping as the ever larger ships themselves. Dredging changes water quality, alters biological systems, and modifies habitat. Must the growth of ports and cities come with high costs to the environment? This chapter assesses the ability of sector-based management to address this conflict.
The growth of shipping In 1847 San Francisco was a small village that was occasionally visited by whaling vessels. In 1849 the discovery of gold attracted more than eight hundred ships, and everything began to change (Labaree et al., 1998).The gold rush, a large harbor, and sea transportation connected coastal Cali fornia with the rest of the world. Rapid growth followed. By 1860, San Francisco was the fourteenth largest city in the United States and a major port. At the time, ships fit easily into the harbor because their drafts (the distance between the waterline and the bottom of the hull) were twenty feet (six meters) or less.The vessels’ relatively small size allowed them to navigate vast areas of sheltered waters, not just around San Francisco but also all along the U.S. coasts, during the first shipping boom. R. Burroughs, Coastal Governance, Foundations of Contemporary Environmental Studies, DOI 10.5822/978-1-61091-016-3_5, © Richard Burroughs 2011
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By the late twentieth and early twenty-first century shipping had changed. Coal and then oil had long since replaced wind as a source of energy to power the ships. Wood hulls were traded in for steel. Most important, the vessels themselves had become much larger to transport more cargo at lower cost. By the 1980s crude oil and containerized car goes traveled on the world’s oceans in vessels that required two or three times the draft of the earlier sailing ships that called on San Francisco. In California manufactured goods from Asia were offloaded in containers at the Port of Oakland (figure 5.1). Changes in the way cargo was handled became important for these bigger ships. Instead of loading a ship with one piece of cargo at a time, individual items were packed into containers, a process that could occur at the point of manufacture, and the containers were loaded aboard the ship using large cranes (Labaree et al., 1998). In the 1950s, the original containers were eight feet (2.4 meters) wide, eight feet tall, and twenty feet (six meters) long, and called twenty-foot equivalent units.They read ily fit on wheels for over-the-road transit as trailers.Today, most contain ers are double that length, but the principle of the operation remains the same. Containers are efficient, but require both large ships and large areas on land for handling.
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