Mean high water springs (MHWS) is the  highest level that spring tides reach on the average over a period of time (often 19 years). The height of mean high water springs is the average throughout the year ( when the average maximum declination of the moon is 23.5° ) of two successive high waters during those periods of 24 hours when the range of the tide is at its greatest . This level is generally close to being the "high water mark" where debris accumulates on the shore annually.
Mean high water springs (MHWS) is the averaged highest level that spring tides reach over many years (often the last 19 ). Within this, to ensure anomalous levels are tempered, at least two successive high waters during the highest-tide 24 hours are taken. Spring tides are those when the moon is an a direct alignment with the sun and in many extra-tropics places when the average declination of the moon is 23.5° , its maximum . This level is generally close to the "high water mark" where debris accumulates on a tidal shore on about two days six months apart (and nearby days) annually.
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averaged
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on the average over a period of time (often
over many years (often the last
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years). The height of mean high water springs is the average throughout the year (
). Within this, to ensure anomalous levels are tempered, at least two successive high waters during the highest-tide 24 hours are taken. Spring tides are those when the moon is an a direct alignment with the sun and in many extra-tropics places
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maximum
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) of two successive high waters during those periods of 24 hours when the range of the tide is at its greatest
, its maximum
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being
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the shore
a tidal shore on about two days six months apart (and nearby days)