Full Information For Harbor

Harbours:

👉A harbour can be defined as a sheltered area of the sea in which vessels could be launched, built or taken for repair; or could seek refuge in time of storm; or provide for loading and unloading of cargo and passengers.

👉Harbours are broadly classified as:

1 Natural harbours

2 Semi-natural harbours

3 Artificial harbours

1. Natural harbours:

👉Natural formations affording safe discharge facilities for ships on sea coasts, in the form of creeks and basins, are called natural harbours.

👉With the rapid development of navies engaged either in commerce or war, improved accommodation and facilities for repairs, storage of cargo and connected amenities had to be provided in natural harbours.

👉The size and draft of present day vessels have necessitated the works improvement for natural harbours.

👉The factors such as local geographical features, growth of population, development of the area, etc. have made the natural harbours big and attractive. Bombay and Kandla are, examples of natural harbours

2. Semi-natural harbours: 

👉This type of harbour is protected on sides by headlands protection and it requires man-made protection only at the entrance.

👉Vishakhapatnam is a semi-natural harbour.

3. Artificial harbours:

👉Where such natural facilities are not available, countries having a seaboard had to create or construct such shelters making use of engineering skill and methods, and such harbours are called artificial or man-made harbours.

👉Madras is an artificial harbour.

Requirements of commercial harbour:

👉Spacious accommodation for the mercantile marine.

👉Ample quay space and facilities for transporting; loading and unloading cargo.

👉Storage sheds for cargo.

👉Good and quick repair facilities to avoid delay.

👉More sheltered conditions as loading and unloading could be done with advantage in calmer waters Accessibility and size of harbours

👉Accessibility depends on the location of the harbours.

👉The harbour entrance should be designed and located for quick easy negotiation by ships, overtaken by storms.

👉At the same time, it should be narrow enough not to expose the harbour to the effects of the stormy sea.

👉Maximum dimensions upto 180 have been adopted

👉The entrance is generally placed of the sea, with a passage to the interior of the harbour so arranged as to minimize the effect of rough seas.

👉Thus; the size is determined by:

👉Accommodation required.

👉Convenience for maneuvering and navigation.

👉Adaptability to natural features.

Site selection:

👉The guiding factors which play a great role in choice of site for a harbour are as follows :-

👉Availability of cheap land and construction materials

👉Transport and communication facilities

👉Natural protection from winds and waves

👉Industrial development of the locality

👉Sea-bed subsoil and foundation conditions

👉Traffic potentiality of harbour

👉Availability of electrical energy and fresh water

👉Favorable marine conditions

👉Defence and strategic aspects

👉Shape of the harbour:

👉The following principles should be kept in mind:

👉In order to protect the harbour from the sea waves, one of the pier heads should project a little beyond the other.

👉Inside the pier heads, the width should widen very rapidly.

👉The general shape of the harbours should be obtained by a series of straight lengths and no re-entrant angle should be allowed

Harbour planning:

👉The important facts to be studied and scrutinized can be enumerated as follows:

👉It is necessary to carry out a thorough survey of the neighbourhood including the foreshore and the depths of water in the vicinity

👉The borings on land should also be made so as to know the probable subsurface conditions on land. It will be helpful in locating the harbour works correctly

👉The nature of the harbour, whether sheltered or not, should be studied.

👉The existence of sea insect undermine the foundations should be noted.

👉The problem of silting or erosion of coastline should be carefully studied.

👉The natural metrological phenomenoa should be studied at site especially with respect to frequency of storms, rainfall, range of tides, maximum and, minimum temperature and of winds, humidity, direction and velocity of currents, etc.

Breakwaters: 

👉The protective barrier constructed to enclose harbours and to keep the harbour waters undisturbed by the effect of heavy and strong seas are called breakwaters.