Lake level?

[callejera]

Does anyone have any information on the lake level with all this rain? I am wondering if any gains are cancelled out by the water we have been sending to Guadalajara...or are we still sending it?

[cedros]

4 minutes ago, callejera said:

Does anyone have any information on the lake level with all this rain? I am wondering if any gains are cancelled out by the water we have been sending to Guadalajara...or are we still sending it?

I check every day. No gains so far. Remember about 90% of the lakes's watershed is east of the east end of the lake. Did it rain much there? If it did did the many dams on the Lerma river (the lake's main inlet) let any water through. to the lake.

[ibarra]

ajijicnews.com has a section titled "lake levels".

[Mainecoons]

Too soon.

[gringohombre]

I walk every day along the small bridge and malacon fronting my house in  lower SAT so I see the reality of the lake level. I have been doing this for almost 14 years. Last year during the rainy season it seemed to fill to the "normal" level and this year it seems to be the same for this early in the season. I have seen it very low and high but as said above is much to soon to prognosticate.   

[barrbower]

When the average depth of the lake is only twelve feet the total volume can change quickly...both increase and decrease.  If the shoreline has moved out, say, thirty feet it could represent a total volume loss of 50% which is where we are now.  It could mean only a drop in level of four or five feet but over the large surface of the lagoon, that is half of the lake volume.  Most of the drop seen every year is from evaporation not draw-down from Guadalajara.  If the depth of the lake was averaging 150 feet the lake would only be abut 1/10th the area it covers now and you would hardly notice the dry season change in level.  Cedros is correct in that the level is very much dependent on rains and inflow from areas east of here.  You'll notice it when the lirio starts showing up when dams are releasing water.

Some day it will all be wetlands and then slowly become a seasonally verdant plain.  But not this year.

Alan

[Mostlylost]

6 minutes ago, barrbower said:

When the average depth of the lake is only twelve feet the total volume can change quickly...both increase and decrease.  If the shoreline has moved out, say, thirty feet it could represent a total volume loss of 50% which is where we are now.  It could mean only a drop in level of four or five feet but over the large surface of the lagoon, that is half of the lake volume.  Most of the drop seen every year is from evaporation not draw-down from Guadalajara.  If the depth of the lake was averaging 150 feet the lake would only be abut 1/10th the area it covers now and you would hardly notice the dry season change in level.  Cedros is correct in that the level is very much dependent on rains and inflow from areas east of here.  You'll notice it when the lirio starts showing up when dams are releasing water.

Some day it will all be wetlands and then slowly become a seasonally verdant plain.  But not this year.

Alan

Exactly which dams are you referring to?  There is a one in the state of Mexico called Solis but the vast majority of the Lerma watershed has no other dams that I am aware if. 

[cedros]

How about at least five hundred and twenty seven dams.

The lerma river major tributaries, the Laja, Apaseo, and Turbio the Lerma constitutes Mexico's largest river system. The Lerma River is not navigable by water craft, but it is critical to regional agricultural irrigation.^[2] In the Lerma River/Lake Chapala watershed, 52,125 of the total 78,000 (roughly 67%) farmers are classified as small farmers. Currently 820,000 hectares are irrigated and an estimated three million hectares are in agricultural production.

There are dams on the major tributaroies of the Lerma. Reservoirs were developed well before the 12th century, including the Lerma - Chapala Basin Case Study: a fruitful sustainable water management experience 9 Figure 18: Lake Chapala. Influence Area dynamics Source: CONAGUA, Organismo de Cuenca Lerma-ChapalaPacífico, 2006 adaptation of lakes and wetland development. During the 16th and 17th century, important irrigation works were developed in the mid-basin where agriculture flourished and was instrumental to colonial sustainability. In the 20th century, modern irrigation became more widespread based on many high capacity dams and dykes together with irrigation districts, rural irrigation units, concrete channels and infrastructure to control water flows.

The basin boasts 527 reservoirs and secondary dams, of which 23% are large dams (according to the ICOLD). Almost 52% of all reservoirs are presently dedicated to irrigation districts and units. Hydraulic infrastructure meant for fluvial and flood control, of paramount importance, due to erratic rainfall behavior only represents 3% of all hydraulic works, although flood control capacities do also exist in most large dams.

fierce competition exists among small dams retaining as much water as possible, reducing inflow to larger dams and a great risk especially when late floods occur. Sediments are slowly being accumulated in most reservoirs, derived from hydraulic.

 The above comes from; "Lerma - Chapala Basin Case Study. Mexico a fruitful sustainable water management experience Prepared for the 4th UN World Water Development Report “Managing water under uncertainty and risk” 

[traderspoc]

Lake always  goes up 36 inches every  rainy season, one exception when we had heavy rain east of us the lake when almost 7 feet

[cedros]

The lake does not always go up 36 inches every year. A glance at Conagua charts of the lake level show that.

[Ferret]

This is the link from which Cedros quote comes... Lerma - Chapala Basin Case Study: a fruitful sustainable water management experience (conagua.gob.mx)

 

[Floradude]

All what rain?

The rain I received in Upper Ajijic for the past 48 hours totaled less than 1/2 inch.  Anyway, the rain we receive here does not have much influence on the lake level.

[Mostlylost]

Of those 527 licensed reservoirs many do not discharge anything to the river.  The vast majority are only a few hectarias with a dirt "dam" 5-10 meters high.. Think Ixtlauhuacan. They are licensed on small streams that only have water in the rainy season and do not discharge to the river. They are there to extend the growing season by providing water to local agriculture. If anything they prevent water from entering the river and lessen the flow.

On the river itself there are a few weirs that are 3 or 4 meters tall and water flows over those year round.  

Pictured is what could possibly be called a dam near Ibarra in Michoacan. It has no gates to open. When the area behind it is full the water flows over the concrete spillway.  The reservoir behind it is very shallow and dries up to almost nothing in the dry season.

[AndyPanda]

Nonetheless, there they are.

[Mostlylost]

I would guess you have never traveled through that area. The only dam that has any quantity of water that gets "released" is in the state of Mexico. The amount that passes over the weirs hardly changes year round with the exception of the one in Ibarra. The river actually bypasses that reservoir all year 

[Floradude]

Conditions at 10:30am 6/28/21	Temperature 64.4°F
Dew Point	59.5°F
Humidity	84%
Barometer	30.18in   Rate 0.011in/hr
Wind Direction	ENE
Heat Index	69.2 °F
UV Index	0.9
Solar Radiation	84
Rainfall  for Today	0.04 in
Rainfall  for 24 Hours	0.06 in
Last Rainfall date	6/28/21
Total Rainfall since 1/1/2021	4.72 in

[Ferret]

Most of the dam/reservoirs are a hold until flow over  and have no specific mechanisms for the release of water. We don't get ours until they get theirs... trickle down effect.

[AndyPanda]

1 hour ago, Mostlylost said:

I would guess you have never traveled through that area. The only dam that has any quantity of water that gets "released" is in the state of Mexico. The amount that passes over the weirs hardly changes year round with the exception of the one in Ibarra. The river actually bypasses that reservoir all year 

No, and I fail to see the relevance. You said there is only one dam on the Lerma. It was pointed out that there are 527 of them.

[Mostlylost]

1 hour ago, AndyPanda said:

No, and I fail to see the relevance. You said there is only one dam on the Lerma. It was pointed out that there are 527 of them.

There are absolutely not 527 dams on the river.  They are reservoirs in the basin. Huge difference.  Most do not discharge any water that would eventually reach the river.    Example is the reservoir in Ixtlahuacan there is no exit for water.  

The "dam" in Ibarra overflows when the area behind it is full. It is a side channel from the river which flows around it all year. When water reaches a certain level it enters the storage behind the "dam" .  At all times the river is flowing past the entrance to that storage area.

Someone give me the name of an actual dam that has regulated discharge that "they can open"  on the Lerma other than the Solis dam in the state of Mexico.

[AndyPanda]

So you are saying the quote above is incorrect? It says, and I quote "reservoirs and secondary dams". Seems like you doth protest too much. Why are you quibbling about this? In the end I don't think anyone here really cares, in the long run. I have certainly lost interest.

[RickS]

 

Pot calling.....

[AndyPanda]

So I question the authority and you throw an insult? What else is new, Rick? Next time you complain about someone hijacking a thread, return here.

[Mostlylost]

I only commented because every year the same myth is repeated.  There just aren't any dams that they can open up other than Solis.  It is increased flow from the watershed of the Lerma not from dams being opened.

Also the majority of our lirio and water lettuce comes from the vast marshy areas at the east end of the lake, and as the water rises they are freed and the wind from the east carries them west. 

To have a dam you need an area behind it with elevation on at least two sides. The vast majority of the Lerma basin is very flat land populated by small volcanic rises The one place the federal government thought of building a dam way back in the 40's never happened. 

 

[lcscats]

So can you both shut up now that you have proven how stubborn you are.

[AndyPanda]

Wow, lcs. Let me refer you back to RickS.

Regarding the topic at hand, I appreciate Mostly's much more succinct final comment, and only wish he'd started with that.