1、 CHAPTER 11 HIGHWAYS ALONG COASTAL ZONES AND LAKESHORES 2007 by the American Association of State Highway and Transportation Officials. 2007 by the American Association of State Highway and Transportation Officials.CHAPTER 11 TABLE OF CONTENTS 11.1 INTRODUCTION. 11-1 11.1.1 Purpose of this Chapter.
2、11-1 11.1.2 Areas Covered by this Chapter . 11-1 11.1.2.1 Coastal Zone 11-1 11.1.2.2 Lakeshore. 11-1 11.1.3 Role of the Hydraulics Engineer. 11-1 11.1.3.1 Highway Planning Considerations. 11-2 11.1.3.2 Highway Location Considerations. 11-2 11.1.3.3 Legal Considerations . 11-2 11.1.3.4 Construction C
3、onsiderations 11-2 11.1.4 References. 11-2 11.2 DATA COLLECTION . 11-3 11.2.1 Hydrologic and Hydraulic Data 11-3 11.2.1.1 Meteorological Data. 11-3 11.2.1.2 Hydraulic Data. 11-3 11.2.2 Engineering Data 11-4 11.2.3 Environmental Data 11-4 11.2.4 Regulatory Data 11-4 11.3 SHORELINE TOPOGRAPHY . 11-4 1
4、1.3.1 Beaches . 11-5 11.3.1.1 Sand Beaches . 11-6 11.3.1.2 Sand Dunes 11-6 11.3.1.3 Non-Sand Beaches. 11-7 11.3.1.4 Beach Sediment Variability . 11-7 11.3.2 Bluffs and Headlands 11-7 11.3.3 Mud Flats 11-8 11.3.4 Wetlands . 11-8 11.3.5 Estuaries 11-9 11.3.6 Inlets 11-9 11.3.7 Lake Shoreline 11-10 11.
5、4 CHARACTERISTICS OF WAVES AND CURRENTS. 11-11 11.4.1 Overview. 11-11 11.4.2 Gravity Waves 11-11 11.4.2.1 Wave Characteristics . 11-11 11.4.2.2 Relative Depth . 11-12 11.4.2.3 Wave Generation . 11-12 11.4.3 Wave Transformations 11-13 11.4.3.1 Shoaling . 11-13 2007 by the American Association of Stat
6、e Highway and Transportation Officials.Highway Drainage Guidelines 11-iv 11.4.3.2 Breaking 11-13 11.4.3.3 Refraction 11-13 11.4.3.4 Diffraction .11-14 11.4.3.5 Decay.11-14 11.4.4 Tsunamis11-14 11.4.5 Tides 11-14 11.4.6 Currents .11-15 11.4.7 Storm Surges .11-15 11.4.8 Longshore Current.11-16 11.4.9
7、Longshore Transport .11-16 11.5 DESIGN CONSIDERATIONS 11-16 11.5.1 Introduction .11-16 11.5.2 Design Waves11-17 11.5.2.1 Wave Distribution .11-17 11.5.2.2 Source of Wave Observation Data 11-17 11.5.2.3 Wind and Wave Setup.11-17 11.5.2.4 Waves over Flooded Areas11-18 11.5.3 Wave Action on Lakes and T
8、idal Basins.11-18 11.5.4 Tidal Flow through Structures.11-18 11.5.5 Scour11-19 11.5.6 Environmental Concerns .11-20 11.6 SHORE PROTECTION DEVICES.11-20 11.6.1 Seawalls.11-21 11.6.2 Revetments 11-22 11.6.2.1 Rigid Revetment11-22 11.6.2.2 Flexible Revetment11-23 11.6.3 Retards.11-24 11.6.4 Jetties .11
9、-24 11.6.4.1 Stone11-25 11.6.4.2 Precast Concrete Blocks11-25 11.6.5 Groins 11-26 11.6.5.1 Materials11-26 11.6.5.1.1 Stone11-27 11.6.5.1.2 Concrete 11-27 11.6.5.1.3 Steel.11-27 11.6.5.1.4 Timber .11-27 11.6.5.2 Alignment11-28 11.6.5.3 Permeability.11-28 11.6.6 Breakwater Systems 11-28 11.6.7 Bulkhea
10、ds 11-30 11.6.8 Beach Nourishment .11-31 11.7 PLANNING FOR SHORELINE CHANGES.11-31 11.7.1 Shoreline Changes.11-31 2007 by the American Association of State Highway and Transportation Officials.Highways along Coastal Zones and Lakeshores 11-v11.7.2 Rate of Shoreline Change . 11-32 11.7.3 Sea Level Ri
11、se. 11-32 11.7.4 Considerations in Planning for the Future 11-33 11.7.4.1 Condition Assessment 11-33 11.7.4.2 Objectives of a Vulnerability Study. 11-33 11.7.4.3 Coastal Highway Vulnerability Model 11-34 11.7.4.4 Emergency Evacuation Plan 11-35 11.8 CONSTRUCTION AND MAINTENANCE CONSIDERATIONS . 11-3
12、5 11.8.1 Construction-Related Considerations . 11-35 11.8.2 Maintenance-Related Considerations . 11-35 11.8.2.1 Maintenance during Construction 11-36 11.8.2.2 Perpetual Maintenance. 11-36 11.9 REFERENCES 11-36 11.9.1 Cited References . 11-36 11.9.2 Additional Publications. 11-37 11.9.3 Web-Related R
13、eferences. 11-39 2007 by the American Association of State Highway and Transportation Officials.Chapter 11 Highways along Coastal Zones and Lakeshores 11.1 INTRODUCTION 11.1.1 Purpose of this Chapter Highways that are located near coastlines and shorelines of oceans, tidal basins, bays, estuaries, l
14、arge lakes, reservoirs, and the lower reaches of many major river systems present challenging design conditions for roadway, structural, and hydraulics engineers. More than half of the States border or contain major coastlines and/or lakeshores. Much of the discussion in other chapters applies to th
15、ese areas but does not address in detail the special aspects of wind, wave, current, and tidal action upon banks and shores. These aspects are covered in this chapter. 11.1.2 Areas Covered by this Chapter 11.1.2.1 Coastal Zone The boundary between the land and water is commonly called the coastline
16、or shoreline. The strip of land of indefinite width that extends inland to the first major change in terrain is commonly referred to as the coast or coastal zone. The coastal zone may be several kilometers miles wide. The exact legal definition of the coastal zone will vary between coastal States. 1
17、1.1.2.2 Lakeshore The lakeshore, like the coastal zone, refers to the strip of land from a lake shoreline inland to the first major change in terrain. Except for tidal effects, large lakes and reservoirs of 300 km2(100 mi2) or more in area have shores that require many of the same type consideration
18、s as oceans, bays, and estuaries. Reservoirs used for power generation or flow control that have daily fluctuations in their pool level may also exhibit characteristics analogous to tidal effects. 11.1.3 Role of the Hydraulics Engineer The highway hydraulics engineer must work with the other highway
19、 disciplines in the planning, location, design, construction, and maintenance of bank and shore protection systems. Many of the nations major ports and transportation terminals are located on the coast, while others are located on inland waterways, lakes, or reservoirs. Highways serve, in addition t
20、o large shipping and commercial 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 11-2 fishing industry interests, small boat harbors and marinas with their attendant docking and launching facilities for sport fishing and other recreational ac
21、tivities. Ocean and lakeshores are very popular recreational areas where many of the nations parks and beaches are located. These areas are often sensitive, sociologically and ecologically, and highway personnel of all disciplines are often called upon to design, construct, and maintain highways in
22、a manner that is compatible with the natural environment. Environmental concerns can range from immediate to long-term cumulative and potential impacts on endangered species, air quality, and water quality. The complexities of these potential impacts require that hydraulics engineers work closely wi
23、th an interdisciplinary team to be sure that the project can achieve its objectives with minimum environmental impact. 11.1.3.1 Highway Planning Considerations The hydraulics engineer may be called upon for advice because of his/her expertise and understanding of problems associated with highways in
24、 the coastal or lakeshore environment. Advice in route selection and potential problem identification may prevent future problems. 11.1.3.2 Highway Location Considerations The hydraulics engineer should be involved during the location phase. There are many special considerations regarding the locati
25、on of a highway in a coastal or lakeshore environment that must be evaluated and analyzed by a hydraulics engineer, who in turn may solicit help from coastal geologists, coastal engineers, oceanographers, or other specialists in the interaction of wind, tides and waves. 11.1.3.3 Legal Considerations
26、 The hydraulics engineer should be familiar with Federal, State, and local permit and navigational requirements. Permitting requirements can be considerably complicated for projects in the coastal zone and lakeshore. The hydraulics engineer should also be familiar with regulations relating to constr
27、uction of bank and shore protection measures and other coastal zone management issues. 11.1.3.4 Construction Considerations The hydraulics engineer must also recognize that there may be special problems related to the scheduling and construction methods that may be employed along the coast. Potentia
28、l environmental impacts may restrict the times for certain activities. Weather restrictions may also limit construction activities. In addition, there may be restrictions on the types and quantities of materials that may be used in coastal construction due to potential adverse environmental impacts.
29、 11.1.4 References There are numerous sources of information on the subjects covered by this chapter. Several references are noted in Section 11.9.1The reader is also directed to Chapter 18, “Coastal Zone,” of the AASHTO Model Drainage Manual (MDM) (1) for information on coastal engineering design.2
30、The material contained in this chapter is intended to complement that presented in the MDM. Duplication of 1In several locations throughout Chapter 11, reference is made to the Shore Protection Manual, published by USACE in 1984 (10). That document is out of print and was replaced by the Coastal Eng
31、ineering Manual (14) in 2002. 2Numbers in parentheses refer to publications in “References” (Section 11.9). 2007 by the American Association of State Highway and Transportation Officials.Highways along Coastal Zones and Lakeshores 11-3information has been avoided to the extent practicable. This chap
32、ter should be read in conjunction with Chapter 18 of the MDM, which also contains a useful glossary of coastal and lakeshore terms. 11.2 DATA COLLECTION Much of the survey and data collection needed for hydraulic studies related to shorelines is the same as that required for other types of hydraulic
33、 studies. However, there are certain items that are more pertinent to shorelines, and it is these items that will be discussed in the following sections. 11.2.1 Hydrologic and Hydraulic Data Coastlines and shorelines present the engineer with challenging conditions due to attack from the large expan
34、se of adjacent open waters. The forces in coastal and lake areas are more diverse than in typical riverine conditions, and the data requirements are more extensive. There are several distinct types of hydraulic problems that may be encountered: wave, surge, and tidal action along a coastline; floods
35、 resulting from upland runoff in combination with tides and waves; and fluctuations in reservoir level due to water management and power generation. Needed data can be obtained from official public records and private sources such as those noted in the following sections. Field reconnaissance provid
36、es an understanding of local topography, vegetation and environmental conditions. Discussions with local residents often produces information on past storm and flood events and better understanding of shoreline response to those events. 11.2.1.1 Meteorological Data Information on storm patterns, pre
37、vailing wind conditions, tide levels, and rainfall records of past occurrences are available from agencies such as the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Army Corps of Engineers (USACE). Both of these agencies maintain rich web sites with numerous databases appropria
38、te to these issues. 11.2.1.2 Hydraulic Data The astronomical and storm tides acting together with wind driven waves are the primary concern on coastlines, estuaries, and delta areas. USACE, NOAA, Federal Emergency Management Agency (FEMA) and State coastal management agencies are sources of informat
39、ion for these areas. Flooding caused by upland runoff in combination with wind setup and/or wave action are the primary concern in dealing with lake shorelines at the mouths of rivers. Other considerations include ice on lakes and the drawdown of the water level for reservoirs that are used for powe
40、r generation, flood control, irrigation, or stream low flow augmentation. Agencies such as the U.S. Bureau of Reclamation, Tennessee Valley Authority (TVA), USACE, State water management agencies, and the private owners of reservoirs are sources of information on past performance, operating procedur
41、es, and the probable response of the waterbody to future hydraulic conditions. Along both coastal and lakefront shorelines, bluffs are often subject to groundwater seepage. This can cause sloughing of the bluff and subsequent shoreline retreat. 2007 by the American Association of State Highway and T
42、ransportation Officials.Highway Drainage Guidelines 11-4 11.2.2 Engineering Data Stabilization of the shoreline is one of the most important considerations when highway facilities are located in that area. The design of foundations and protective works must be predicated on knowledge of local soils
43、and geology. It is also necessary to determine the dominant geomorphic processes. This type of information may be obtained from borings, soil surveys, stereoscopic analysis of aerial photographs, and field reconnaissance. Because shorelines may have significant temporal variability, it is necessary
44、to obtain sufficient historical data to identify either this variability or long-term trends. The hydraulics engineer needs to recognize that these changes may be seasonal, annual, or even longer at some locations. Both the position and the geometry of the shoreline are subject to change. At some sh
45、orelines, there may also be significant spatial variability. The engineer needs to obtain sufficient data along the shoreline to be able to understand this potential variability. At a minimum, data collection at intervals on the order of 150 m (500 ft) should be considered if there is reason to beli
46、eve that spatial variability might be a concern. 11.2.3 Environmental Data Shorelines usually support diverse and highly productive ecosystems. They also provide educational and recreational resources. The environmental compatibility of the highway facility along the shoreline with the natural syste
47、m must be given careful and thorough consideration. Chapter 10, “Evaluating Highway Effects on Surface Water Environments,” addresses many of the data requirements. Information on those features peculiar to coastal shorelines such as salt-water intrusion, saline-freshwater mix, and estuarine wetland
48、s will require additional data collection. The engineer should seek the assistance of an environmental specialist when identifying data needs and methods of acquisition. 11.2.4 Regulatory Data Highway activities along shorelines will be involved with the environmental regulatory process and may also
49、 be subject to navigation and other regulations. Restrictions, stipulations, and permits may be required by USACE, U.S. EPA or a State-designated protection agency, USCG, State coastal zone management agencies and wetlands boards, and other agencies. Most activities in the coastal zone will require both Federal and State permits. Frequently, a single permit process will deal jointly with both. The highway engineer is cautioned to work closely with these
