Mean low water (MLW) is the average height of all low waters at given place.

平均低水位(MLW)为给定地区所有低潮位的平均值。

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The reason for the excitement is that, although the existence of ice on Mars has been known since 1666, when the planet's polar caps were first seen, the low temperatures and air pressure there mean that water, even if heavily salted, is likely either to freeze or to evaporate.

ECONOMIST: Water on Mars

Water reserves are low one more dry winter will mean a certain drought in 2002.

ECONOMIST: California on the couch

What does that mean? 30 miles out, it would not be dangerous to come into contact with water with low radioactive iodine concentrations.

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