The Ganga action plan was, launched by Shri Rajeev Gandhi, the Prime Minister on 14 Jan. 1986 with the main objective of pollution abatement, to improve the water quality by interception, diversion and treatment of domestic sewage and present toxic and industrial chemical wastes from identified grossly polluting units entering into the river.

A tidal bore, often simply given as bore in context, is a tidal phenomenon in which the leading edge of the incoming tide forms a wave (or waves) of water that travels up a river or narrow bay against the direction of the river or bay's current.

The spring tide occurs when the moon, the sun and the earth make in angle of $180^0$.

Neap tides are produced in the first and third quarters of the moon. Then the attractions of the Sun and the Moon are at right angles to each other.

• Tides are the rise and fall of sea level caused by the combined effects of gravitational forces exerted by sun, moon and earth.
  
• Tidal range is the vertical difference between high tide and its succeeding low tide.
  

During an earthquake, surface waves cause the most damage. Unlike other seismic waves that move deep inside the Earth, surface waves move along just under the surface of the Earth like waves in water. Surface waves are the slowest seismic waves and are the final waves to hit an area after an earthquake. 

First, P-waves move through compression through the deep layers of the Earth. P-waves are also carried by air and water, causing them to make a sound when they hit the Earth's surface. They result in minimal damage. The second group of waves is S-waves. They move up and down starting deeper in the Earth, and they cannot travel through air or water. Stronger S-waves do some damage when they reach the surface. Surface waves move in last. Their slow roll just under the surface provides the greatest risk for damage to man-made structures and changes to natural landforms.

When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide. Spring tides are especially strong tides (they do not have anything to do with the season Spring). They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. Spring tides occur during the full moon and the new moon.

When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide. Spring tides are especially strong tides (they do not have anything to do with the season Spring). They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. Spring tides occur during the full moon and the new moon.

In cold countries, tides bring in saltwater and by their constant motion prevent harbours from becoming icebound. Low-lying areas along the sea-coast which get the seawater during high tides can be used to produce salt by trapping the water.

The rhythmic rise and fall of ocean water twice in a day is called a tide.

The strong gravitational pull exerted by the sun and the moon on the surface of the earth causes the tides.

Seven days after a spring tide, the sun and moon are at right angles to each other. When this happens, the bulge of the ocean caused by the sun partially cancels out the bulge of the ocean caused by the moon. This produces moderate tides known as neap tides, meaning that high tides are a little lower and low tides are a little higher than average. Neap tides occur during the first and third quarter moon, when the moon appears "half full."

Neap tides occur when the Moon and Sun form a right angle with the Earth. In contrast to spring tides, neap tides are the effect of tidal forces canceling each other.

Tides are caused by the moon. The tidal force causes Earth and its water to bulge out on the side closest to the moon and the side farthest from the moon. These bulges of water are high tides. It is because of high tides only that the sea level rises.

Very high tide is caused when the sun, the moon and the earth are almost in the same line. Such high tides are called spring tides. During new moon and full moon the gravitational forces of sun and the moon work together with combined force and thus this spring tide occurs. 

On an average, every place experiences high and low tide a day at an time interval of 12 hours 25 minutes. Since the earth completes its rotation in roughly 24 hours, every place should experience tide after 12 hours but this never happens. Each day tide delayed by 25 minutes because the moon also rotates on its axis while revolving around the earth. 

The rise and fall of sea water due to gravitational forces of the sun and the moon are called tides. In fact, tides are the most uniformly varying phenomenon in the ocean. 

Wave Crest is the point on a wave with the maximum value of upward displacement within a cycle. A crest is a point on a surface wave where the displacement of the medium is at a maximum.

A trough is the minimum or lowest point of the value of displacement within a cycle. 

Wavelength is the distance between one crest or trough to the next crest or trough. It is the distance between identical points in the adjacent cycles if a waveform signal propagated in space or along a wire.

Wave height is the distance between the crest and trough. The wave height of a surface wave is the difference between the elevations of a crest and a neighboring trough. Wave height is a term used by mariners, as well as in coastal, ocean and naval engineering.

Waves in the sea surface are generated by the action of the wind. The height of the wind waves increases with the increasing wind speed and with increasing duration and fetch of the wind. As the speed of the wind increases, the strength of the wave also increases.

Waves are actually the energy, not the water as such, which moves across the ocean surface. Water particles only travel in a small circle as a wave passes. Wind provides energy to the waves. Wind causes waves to travel in the ocean and the energy is released on shorelines. Thus, it is due to waves only that water moves horizontally over vast areas.

Waves are actually the energy, not the water as such, which moves across the ocean surface. Water particles only travel in a small circle as a wave passes. Wind provides energy to the waves. Wind causes waves to travel in the ocean and the energy is released on shorelines.

2 low tides and 2 high tides are experienced every lunar day, 

Tide with the greatest difference between the high and low tide, 

Tide with the greatest difference between the high and low tide, that occurs just after a new or full moon is a spring tide.

Offshore in the deep ocean the difference in tides is usually less than 1.6 feet. The highest tides can however have a range of 44.6 feet, observed in the Bay of Fundy, Canada.

Tides are the result of the gravitation pull of the Moon on the Earth's water body.

Rise and fall of the surface of the Earth's water body due to the gravitation pull of the Moon and the Sun on the Earth is tides.

Neap tides occur twice a month when the Sun and Moon make a angle of 90 degree with the Earth. Such tides are the weakest tides.

Neap tides are the tides with the least difference between the high and low tide. Neap tides occur just after the first or third quarters of the Moon.

Tide where the difference between the high tide and low tide is the least is called a neap tide. Such tides occur when the Sun and the Moon are in a right angled position with the Earth. This happens twice in a month.

Tides are caused by the combined gravitation attraction of the Sun and Moon on the Earth. Force that results in a motion between a body and a tangential surface is called a tractive force.

The main cause of tides in an ocean is the gravitational pull of the Moon on the Earth.

Although tides are caused due to all the above reasons, the main reason behind it is the gravitational effect of the Moon on the Earth. Moon is closed in a bound state with Earth, and due to this the effect of its gravitation is more on Earth than that of Moon on Earth.