Module 8 Lab

Module 8 Lab

Introduction

The objective of this Lab is to help you develop an appreciation for coastal erosion and associated risks when placing major infrastructure proximal to coastal hazards.

Ocean Beach is a sandy beach backed by erodible bluffs that form the boundary between the western edge of the city of San Francisco, CA and the Pacific Ocean. Like many sandy coasts around the world, portions of Ocean Beach have experienced significant erosion in the past decades. The long-term erosional trend along the southern reach of the beach has been punctuated by periods of intense erosion during particularly severe winter El Niño storm seasons, when the beach and backing bluffs can be exposed to very high waves.

The situation is complicated by the presence of critical infrastructure within the coastal zone. The Great Highway, an important transportation link, is located on top of the bluffs backing Ocean Beach, and recent erosional events damaged parking areas and forced the closure of one direction of traffic for much of the storm season. More importantly, a large sewage tunnel runs under the Great Highway, transporting the city’s wastewater south to a treatment plant. Continued erosion threatens this piece of expensive, critical wastewater infrastructure, and it must be protected in the near term to prevent both the environmental consequences of a tunnel failure and the huge cost of relocation. During the most intense erosion episode during the 2009-2010 El Niño winter, the city constructed an emergency revetment of armored stone along the eroding bluff to protect the wastewater infrastructure; however, the use of “hard” coastal protection structures met stiff opposition from environmentalists and local regulatory agencies due to the inevitable loss of beach in front of the structure.

A parking lot and bench between the Great Highway and the bluff edge at Ocean Beach before (2009) and after (2011) severe erosion.

Credit: SPUR

Lab Overview

After you thoroughly read the article “SPUR: The Future of Ocean Beach” (mentioned above, follow the steps in the Module 8 Lab Worksheet below.

Downloads/Resources

• Module 8 Lab Worksheet

Instructions

Before you begin the Lab, you will need to download the Lab worksheet. We advise you to either print or download/save the Lab worksheet, as it contains the steps you need to take to complete the Lab in Google Earth. In addition, it contains prompts for questions that you should take note of (by writing down or typing in) as you work through the Lab.

Once you have worked through all of the steps, you will go to the Module 8 Lab to complete the Lab by answering multiple-choice questions. The answers to questions on this Lab worksheet will match choices in the multiple-choice questions. Submit the quiz for credit.