Close to the base level.
The altitude of a plain can vary, but it is mostly flat and close to sea level. Plains can be found at various elevations, from below sea level to several thousand feet above sea level.
Oh yes, otherwise NYC would be under water. It lies at the open sea.
There are three Chelseas in New York. All are pretty close to the waterfront, which puts them under 40 feet above sea level.
800mb (now hectoPascals) is approx. 6500ft or 2000m above sea level. It is not a well-used Standard Level, as 850hPa is close and the next one is 700hPa.
The results of a lower base lever for rivers and streams is the sea level falls and the land rises. The base level is the level below which a stream cannot erode.
They are fresh water. They are fed by rivers, streams, glaciers, and are above sea level, so they drain into the sea which prevents the salt water entering the lakes..
As often happens with coastal cities, Barcelona is at sea level.
The 'On Sea' part of the name implies that parts of the town are at or close to sea level.
The Blue Lagoon in Iceland reaches as high as 1000 meters above sea level at it's highest point. Much of it though is much lower than this and quite close to sea level.
downcut
It depends on the weather. In dry weather levels of lake water may go down, and in times of rainfall the levels may rise. (Streams leaving a lake mean that the levels can never rise above that stream level, of course.)
Surface waste is really supplanted by extensive underground seepage. "vanish" (vanishing streams) and "return" (springs). Streams that stream on a superficial level and afterward apparently "vanish" subterranean. They may likewise vanish into cracks or blames in the bedrock close to the stream. A gushing stream gets water from the beginning, in this manner it extends downstream by getting further and more extensive. Influent streams are in parched territories and lose a ton of water through dissipation and drainage into the ground. ... Most influent streams lose the entirety of their water, evaporating before entering the ocean.