Civil Engineering on our Seashore

This piece is about the varieties of Coastal Civil Engineering (CCE) works we all see – when visiting seafront to relax, to feel the warmth of ocean in continuous pounding of waves, or when seeing vessels navigating in and out of ports and harbors. These works result from engineering efforts that have three well-known tenets of civil engineering: coastal hydraulic engineering (or simply Coastal Engineering, CE), coastal structural engineering and geotechnical engineering (structural and geotechnical are often lumped together as structures engineering). Coastal hydraulic engineering term is sort of a misnomer – because it not only covers analysis, modeling and determination of hydrodynamic forces caused by water, water level rise and fall, current, wave and bed-level changes – but also includes similar activities due to wind forcing. The combined effects caused by wind and water are known as metocean processes and forces.   

Before moving further it is important to build into our concept the extent of geographical area where civil engineering is referred to as CCE or CE. This area termed as the coastal zone – extends from the inland topographical limit reached by major storm surges and tsunamis to the continental shelf break. Continental shelf mostly of turquoise water, having an average bottom slope of some 1V:100H extends from the shoreline to a seaward line where the slope abruptly dips down into the ocean at about 1V:40H or steeper. This line begins roughly in the region where waves of about ≥ 10 seconds will start feeling the bottom – consequently being subjected to the transformative processes of refraction and shoaling (see Wave Transformation piece on this page). Generally, mariners call the blue ocean beyond continental shelf – high seas. The definitions of inland limit vary among countries – and depend on several criteria such as: technical, legal, administrative, disaster management and hazard insurance – but they all invariably include coastal waterways, river mouths, estuaries and bays. I have discussed many aspects of CE in different pieces on the NATURE and SCIENCE & TECHNOLOGY (S & T) pages. Thought a piece of introductory nature will complement those.

In the US Submerged Land Act (1953) a coastline is defined as: the line of ordinary low water along that portion of the coast which is in direct contact with the open sea and the line marking the seaward limit of inland waters. The same Act defines coastal submerged land under the jurisdiction of coastal States as: navigable waters, and lands beneath, within the boundaries of the respective coastal states out to 3 nautical miles from its coastline. The Outer Continental Shelf Lands Act (OCSLA 1953) defines federal jurisdiction on coastal oceans as: all submerged lands lying seaward of state submerged lands and waters (e.g. outside shelf lands seaward of 3 nautical miles).

Perhaps it is useful to add a brief on the legal definition of Maritime Boundary. Part of this brief is based on my 1994 IEB paper: On the Formulation of Coastal Zone Management Plan for Bangladesh. The following definitions of the boundaries are agreed upon by signatory countries (including the land-locked countries which are given the right to claim maritime transport access through their coastal neighbor) at the UN Convention on the Law of the Sea (UNCLOS 1987). It was developed and refined within the framework of the UN – during a period from 1970 to 1984.

• To define and demarcate different zones a reference line is required – and this reference line termed as the Base Line (BL) is defined as a delineated shoreline at Mean Low Water (MLW). The BL is delineated to include a country’s nearshore/offshore islands, if any, along with a straight line to enclose bays and estuaries.
• Inland Water (IW): the waters landward of the BL.
• Territorial Sea (TS): the seaward water from the BL to the extent of 12 nautical miles (NM) or ~22 km.
• Exclusive Economic Zone (EEZ): the seaward limit to the extent of 200 NM (~370 km) from the BL. An intermediate Contiguous Zone (CZ) is also defined outside of the TS – seaward to the extent of another 12 NM. One can imagine that with such definitions of BL, TS, CZ and EEZ – each of them represents a series of polylines, roughly mimicking a country’s coastline. A country defining these boundaries owns these waters and has the jurisdictional authority over them: authority to develop and exploit Natural resources (e.g. mineral, fisheries) within its EEZ; authority to control maritime traffic, and to react if a hostile vessel enters its TS without permission. It also has the responsibility to maintain the waters pollution-free and take care of its flora and fauna. A country’s Coast Guard is given the authority to enforce the rights and responsibilities.

Despite the clarity of definitions – legal interpretations differ and disputes often arise – such as the two flashpoints – the Arctic Sea and the South China Sea. As far as the maritime traffic is concerned, the sea beyond the TS – the High Seas belongs to all nations. Note that the definitions of these boundaries have nothing to do with bathymetry (for example, the zone boundary is not affected whether it is a wide or a narrow continental shelf). However, the boundary limit has to be measured along a line perpendicular to the BL. Each country and international organizations issue marine charts showing the demarcated maritime boundaries.

There are other names addressing the same problems of CCE but focusing on some particular aspects: like port and harbor engineering, maritime engineering (coined first in European literature), and marine engineering. The last term is loosely applied in civil engineering to describe in-water works – but its root mainly lies in describing mechanical-electrical engineering, navigation and naval architectural aspects of seafaring vessels. Ocean engineering, oceanographical engineering and offshore engineering terms are also used to describe works in coastal and deep waters. Offshore engineering term is primarily applied to describe isolated in-water works in deep water – like oil terminals and marine pipelines.

There are many definitions of CCE – different in wording but common in contents. Let us attempt to define it in this piece as: CCE refers to the practice of planning, designing and effects assessment of civil engineering works for the protection and preservation of, and developments (water-front townships and cities, recreation, marine transports and installations, and value-adding improvements) within the coastal zone. The history of CE is briefly discussed in the Resistance to Flow on this page – it is a fairly new discipline – the official recognition and definition was launched only about 70 years ago – at the First Conference on Coastal Engineering held in Long Beach, California in 1950. Coming back to the definition – one can see that it relies on the understandings of two other terms: civil engineering, and engineering. There are many definitions of these two terms in literature, but I prefer using the following two.

According to The National Academy of Engineering and National Research Council: engineering is the study and practice of designing artefacts and processes under the constraints of the laws of nature or science and time, money, available materials, ergonomics (it is the process of designing or arranging workplaces, products and systems to satisfy the needs of people who use them) environmental regulations, manufacturability, and repairability. The 2008 ASCE BOK2 (Civil Engineering Body of Knowledge for the 21st Century, 2nd ed.) defines and elaborates civil engineering as: the profession in which a knowledge of the mathematical and physical sciences gained by study, experience, and practice is applied with judgment to develop ways to utilize, economically, the materials and forces of nature for the progressive well-being of humanity in creating, improving and protecting the environment, in providing the facilities for community living, industry and transportation, and in providing structures for the use of humanity. Both of these definitions are quite lengthy, but they were developed to cover all different aspects – from both technical and legal perspectives.   

I have written in the Creativity and Due Diligence piece that, CE as a creative profession has the role . . . in the discipline of civil/hydraulic engineering, applied science provides the baseline knowledge on data and analysis, while technology provides tested products and materials. The role of an engineer is to find solutions to a given problem using resources from these two sources. To do it successfully, it is important for engineers to understand the necessary basics of the S & T. Failing in this matter affects the soundness of an engineer’s judgment. Therefore engineers are part of the S & T endeavors by being intricately involved in the development and progress – sometimes working at the forefront, but most often in the practical applications of science and technological advances to the real-world problems . . . And to accomplish that, engineers by and large, and perhaps more than any other profession – spend a significant portion of their time on computing to create acceptable, defensible and implementable solutions in quantitative terms – using slide rule in earlier times (until about 1970s) to the scientific calculators and personal computers in modern times.

Perhaps it is helpful to enumerate some of the sub-disciplines commonly included in the coastal engineering envelope. The first group (a-group) of activities includes those – aimed at establishing critical planning and design conditions and criteria by envisioning the most probable operational and design loading scenarios, uncertainties and risks for various interventions/structures (these structures not only include hard measures of concrete, steel and stones; but also soft structures like beach nourishment and coastal vegetation/tree barriers) based on analysis and modeling of various environmental parameters. This group includes: (1a) hydrodynamics: water level, current, and wave (2a) wind climate and storms (3a) sedimentary climate: coastal geology and sediment transport processes. The second group (b-group) of activities utilizes the first – for planning, designing and assessing the effects and risks of: (1b) coastal zone development and value adding (2b) coast and shore preservation and protection (3b) intakes and outfalls (4b) dredging and spoil disposal (5b) coastal waterfront and marine terminal structures, including marina  (6b) offshore and pipeline structures (7b) port and harbor developments and structures. I have included an image of the coastal envelope showing the discussed disciplines.

An engineering project starts with a very limited knowledge – starting from that the project moves forward to develop criteria, conditions, specifications, etc. in distinct phases of activities. At the first of three phases – the Conceptual Phase (known as Pre-FEED {Front End Engineering and Design} in Oil and Gas Industries) – starting from scratch problems are defined and the project is visualized, they are then translated into a complete solution package (analysis and design sketches, alternatives, economics, etc) – only at a high level by utilizing available regional and site-specific (mostly unavailable) information. This phase is usually preceded by very high level technical feasibility and economic viability studies. At the next phase – known as the Preliminary Phase (FEED in Oil and Gas Industries) – the conceptual package is critically reviewed, a site-specific information base is established by measurements and modeling, new alternatives are generated, and the conceptual package is revised and updated – but the issued design sketches and specifications are not yet ready for implementation. At the Final or Detailed Phase – a final critical review of the preliminary package is undertaken – updated and refined where necessary, usually no new alternatives are generated – construction, monitoring and supervision methodologies are laid out by detailing each nut & bolt – and the final design sketches and specifications are issued for implementation with the consultant having the additional task of selecting a contractor.

The above phases are usually conducted by different engineering consulting firms for better accommodation of talents and ideas, but often the final phase is eliminated entirely for large projects – by combining the final design and construction into a single package. One prominent form of this system is known as the Engineering, Procurement and Construction or EPC method, where the contractor is responsible for the final design, procurement of materials, and delivering the finished functioning product to the client. To assist and oversee the EPC contractor activities – the project owner usually engages a specialist firm known as the Project Management Consultants (PMC). Apart from these, there are many other consulting, contracting and management terms used in different project phases and construction – and they are usually not the same across civil engineering projects – but vary according to types, even from one country to another.            

A little note on design criteria – they refer to the parameters that must be applied as a minimum for designing project elements; and mostly include: (1) environmental metocean forcing functions, (2) configuration and layout, (3) structural material strength, durability, etc (4) structure-geotechnical, (5) construction and construction foot-prints, (6) operation and maintenance, (7) economics, (8) safety and emergency access, (9) ergonomics, and (10) environmental effects. Some of these criteria are established by scientific and engineering analyses; others come from certified standards and codes; and client and regulatory requirements.           

Having clarified the meanings of different terms let us move on to the rest. Let me begin by listing some of the major works identified with coastal engineering. The list is long – I am tempted to provide a brief outline of some important works that are applied worldwide affording developments of manuals, standards and codes:

1. beach drain {perforated underground drain placed in the swash zone},
2. beach nourishment {placement of imported sands to build new beach and/or to counter-balance beach erosion},
3. breakwater {an in-water self-standing protection structure - shore-attached, detached or offshore - to diffract, break and obstruct waves},
4. bulkhead {retaining structure to protect coastal inland from wave attack},
5. dolphin {port structure – usually a cluster of piles for mooring}
6. floating breakwater {pontoons anchored to seafloor or fixed to guide piles to attenuate mild wave actions; primarily applied to develop Marina where pleasure boats are housed and moored by tying them to finger floats},
7. groin {shore-perpendicular structure spaced suitably to minimize beach erosion},
8. jetty {shore perpendicular structure placed on both sides of inlets to keep navigation functional by interrupting longshore transports},
9. offshore breakwater {submerged or emerged structure to minimize wave action and beach erosion},
10. pier {port structure extending into water for loading and unloading}
11. pile structure {series of piles integrated together by pile caps to support superstructure},
12. pipeline {seabed pipeline to transport liquids and encasing cables},
13. quay {port structure – paved bank or built-up area for ship mooring, loading and unloading}
14. revetment/riprap {shore-parallel stones or manufactured concrete slabs laid on coastal slopes to prevent erosion},
15. sea dike {shore-parallel elevated earth or concrete structure to prevent flooding),
16. seawall {shore-parallel water-front structure to prevent erosion, overtopping and flooding},
17. scour protection {primarily stone ripraps to prevent structure undermining by scour},
18. sluice {drainage outlet generally placed on sea dikes to flush out inland water, and prevent salt-water intrusion},
19. storm surge barrier {structure placed on inlets, estuaries or river mouths that can be closed during storm surge and tsunami onslaught},
20. submerged sill/reef {placed in the nearshore to minimize wave action and beach erosion; the same concept is also often configured to facilitate wave surfing},
21. terminal {fixed or floating marine terminal, platform structure for mooring of ships, loading and unloading}
22. trestle {port structure – rigid frame of short spans used as a support for loading and unloading}
23. training wall {structure configured to direct flow to improve navigation and mooring}
24. wharf {port structure – where vessels can moor alongside for loading and unloading}                   

How does one characterize the failure of a structure – like the listed ones? Failures generally fall into 4 basic types: (a) environmental load failure (the cause for this failure is attributed to the exceedence or unexpected occurrence of design loads and loading conditions), (b) functional or ergonomic failure (although the structural integrity remains intact, the structure fails to provide its designed operations, functions or performance), (c) structural failure and (d) geotechnical failure. The last two could have the following 3 causes: 

• design failures of the structure – wholly or partly including its foundation – are caused by designed elements’ inabilities to withstand the loads used in the design;   
• construction failures are caused by incorrect or bad construction and/or use of unspecified low-quality construction materials and methods – in violation of the design and construction specifications;
• deterioration failures are caused by inadequate or lack of repair and maintenance, specified in the design.

Each of these general failure modes and specific ones – defines the Limit State. A design process examining each state individually – constitutes what is known as the Limit State Design. There are many more features of CE, but for the sake of brevity, I like to stop at this, only to point out one very important aspect. Coastal structures are not like a tall building standing on a dry land – and they should not be treated as such. Because of their exposed location in water or at the water-front, they continuously come under attack by the dynamic and uncertain metocean forcing – from regular to extreme. They must withstand these forces during construction and operational lifetime, as well as face the consequences of uncertain fluid-structure interaction processes, and have to cause minimum impacts on the surrounding environments.

Therefore the role of a coastal engineer is very crucial – not only in the establishment of design and operational conditions and criteria, but also during the process of planning, design and construction. Lack of effective coordination, cooperation and concordance among various disciplines – or perhaps in not recognizing the proper roles required of certain disciplines – could lead to earning bad reputation, and to risks of incurring serious economic losses.        

I like to finish this piece with some lines of poetry written by a seemingly unknown amateur poet, but the poem was made significant by Saint Mother Teresa (1910 – 1997; Nobel Peace Prize 1979; Bharat Ratna 1980; Sainthood 2016) who displayed it in her office.
People are illogical, unreasonable and self-centered
Love them anyway.   
. . .
Give the world the best you have and you’ll get kicked in the teeth
Give the world the best you have anyway.

What motivation went into such portrayals of the societies we live in – and the strength and courage the poet was asking for? One can hardly afford not to like the poem – but perhaps more so by a personality none other than Mother Teresa – because it tells all about her life and experience.

.  .  .  .  .

- by Dr. Dilip K. Barua, 5 February 2019

---