Lake Level

I see from the lake level web page that we're now at a lake level that was not reached last year until Aug 29th.

SunFan

The lake is always 'level', but the elevation of its surface does rise and fall. However, a purist would insist that the surface is never 'level', but actually a curved surface. He would be correct.

Not much to think about today.

I loved your post RV. It is so true.

On a serious note, I sure hope the level keeps on going up as it has so far this year and gets the lake level a little closer to the sea walls or whatever they are called, you know closer to the top of the shore.

I'd like to this...



Photo source...

http://www.eltesorodelajumentud.info/asierach.html

You'd like to what this? Surf!?!

Just how difficult can it be?



...I'd like to see this. Actually both the cow and the flooded pier.

How is the lake level determined? About 100 years ago, they would drop a weighted line from a bridge in Ocotlan to the surface of the lake and measure the difference between the two. The bridge was arbitrarily considered to be the baseline of 100 and the length between the bridge and the water surface was subtracted from 100 to determine the level of the lake relative to the bridge. So if the difference between the bridge and the water was 5.00 meters, the lake level was considered to be 95.00. Well, the bridge is long gone and there now are more sophisticated ways to measure the level of the lake. However, in order to maintain continuity of records over the past 100 years, the old arbitrary baseline and relative level of the lake to that baseline has been retained.

Smartalex

Was that a bridge over the Santiago river that eventually flows out to the Pacific?

SunFan

SunFan, Can't answer your question. I read the historical reference a few years ago...and In Spanish. I remember wondering, like you, exactly where this bridge might have been located.

SunFan wrote:Smartalex

Was that a bridge over the Santiago river that eventually flows out to the Pacific?

SunFan

Yes, the old bridge that was the nearest to the source or the outlet from the lake that was the start of the Rio Santiago.  On the old road to La Barca, that was changed a little some years ago.

RVGRINGO wrote:The lake is always 'level', but the elevation of its surface does rise and fall. However, a purist would insist that the surface is never 'level', but actually a curved surface. He would be correct.

Not much to think about today.  

Level has two quite different meanings.

Smartalex wrote:How is the lake level determined? About 100 years ago, they would drop a weighted line from a bridge in Ocotlan to the surface of the lake and measure the difference between the two. The bridge was arbitrarily considered to be the baseline of 100 and the length between the bridge and the water surface was subtracted from 100 to determine the level of the lake relative to the bridge. So if the difference between the bridge and the water was 5.00 meters, the lake level was considered to  be 95.00. Well, the bridge is long gone and there now are more sophisticated ways to measure the level of the lake. However, in order to maintain continuity of records over the past 100 years, the old arbitrary baseline and relative level of the lake to that baseline has been retained.

There are 3 (now maybe only 2) weather stations on the lakeshore where the level is measured daily. They relate the lake level to the old measurement at that bridge.

SunFan wrote:I see from the lake level web page that we're now at a lake level that was not reached last year until Aug 29th.

SunFan

Yes, it has risen more that half a meter this season.

SunFan wrote:Smartalex

Was that a bridge over the Santiago river that eventually flows out to the Pacific?

SunFan

Yes. But that part of the Santiago flows nowhere now.

If you are referring to overflow from the lake, that rarely ever happens.  just rainy season runoff and tributaries below that outlet source.

slainte39 wrote:If you are referring to overflow from the lake, that rarely ever happens.  just rainy season runoff and tributaries below that outlet source.

The last time water flowed out of the lake was over 40 years ago. In Nayarit where the Santiago river enters the Pacific it is quite large-from streams that enter it along the way.

SunFan: They use a more modern method to determine lake level lake now but the baseline of 100 remains the same whether or not the bridge still exists or whether or not there is outflow to the Rio Santiago. Reread my first post in this thread. I think this is clearly stated.

Cypress: I believe the weather stations you are referring to get their information on the level of the lake from the governmently agency that actually does the measurement. I believe there is a weather station, maintainèd. by that same agency, on Scorpion Island that reports the lake level continuously, probably by monitoring a tethered bouey floating on the lake surface.

I've been to the weather station near me. They have a physical setup to measure the level of the lake-a metal catwalk out into the lake and a ladder down to the vertical measuring board with a metric scale that is based on the 100 baseline. It is a government agency that does this. Maybe that has changed?

That's interesting. Where is this station located? Do they have a website? I'm referring to the government-operated site which had a link posted on the now-closed Chapala Weather site. You could actually watch the lake level rise and fall slightly from moment to moment, as if it were monitoring a bouey floating on the surface. I'll see if I can find the site again and post the link to it here.

https://www.ceajalisco.gob.mx/contenido/chapala/

Smartalex wrote:
https://www.ceajalisco.gob.mx/contenido/chapala/

That is the same government agency that runs the weather sites.

Piedra Barrenada

ferret I think you are right. That information and the weather sites come from CONAGUA. Now they show that the level has gone up 67 centimeters.