Vaal Dam levels

Sinbad said:
I wish they would tell us what they are using to decide whether the drought has broken, and at what levels they will stop the water throttling.
I suspect they are still using the drought as an excuse for ****ed up infrastructure
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Meanwhile yesterday, in Randburg I saw yet another burst pipe making the road become a river...
 
Yesterday afternoon, I drove over the last bridge on the Orange River, about 2km from the mouth at the Atlantic Ocean.

This bridge is about 1km long , single carriageway.

The Vaal River flows into the Orange.

In the last forty years of driving over this river I have not seen the level so low as it was yesterday.

The Once Mighty Orange River.jpg



In addition to the weird weather, Last night we had rains like never before, with only the 2nd recorded incident of hail falling from the skies above the desert......

In Port Nolloth, 90km to the South of us, The wind's from the storm were so strong that they took the roof off the local Spar.

Up in our town, tree's were uprooted and HT power lines were blown over,

Port Nolloth Spar.jpg

The God's are indeed not happy with the little humans..... :twisted:
 
Water dept to continue drawing water from Sterkfontein Dam

JOHANNESBURG – The Water and Sanitation Department says it will continue to draw water from the Sterkfontein Dam for the next 19 days in order to protect the 25% minimum level for the Vaal Dam.

The department started releasing water at the beginning of the month and says it has just about reached the Vaal Dam.

The Vaal river system consists of 14 dams, mainly servicing Gauteng, with at least 13 million users.

The department says the Sterkfontein Dam has decreased by 1.3% to 90% due to the planned release to the Vaal Dam.

It also says the Vaal Dam has increased by 1.9% week on week, to 33.4% due to the rainfall.
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More at: http://ewn.co.za/2016/11/24/water-dept-to-continue-drawing-water-from-sterkfontein-dam
 
Vaal Dam water levels up, drought not over

JOHANNESBURG - The Department of Water and Sanitation says levels at the Vaal Dam have risen due to recent rainfall in Gauteng.

The department has been able to stop water usage from the Sterkfontein Dam.

Spokesperson Sputnik Ratau says that although levels are satisfactory at the moment, it does not mean the drought is over.
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More at: http://ewn.co.za/2016/12/29/vaal-dam-water-levels-up-drought-not-over
 
It's been raining for Africa. How can the droughts not be over? :mad:
 
jingaling said:
It's been raining for Africa. How can the droughts not be over? :mad:
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No it hasn't, not in the right catchment areas, we barely got any rain in the eastern freestate area, with as little 30 odd mm since November, even when there is 15mm or so, the ground is dried out it doesn't even have the opportunity seep into the ground before the sun and heat licks it up again.So no, the drought isn't over not by a long shot....
 
wizardofid said:
No it hasn't, not in the right catchment areas, we barely got any rain in the eastern freestate area, with as little 30 odd mm since November, even when there is 15mm or so, the ground is dried out it doesn't even have the opportunity seep into the ground before the sun and heat licks it up again.So no, the drought isn't over not by a long shot....
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Vaal Dam is in Midvaal which has been receiving a very decent amount of rainfall.

A little alarming so little rain is falling in the eastern Freestate. Hopefully it will improve next month for the farms in those areas.
 
jingaling said:
Vaal Dam is in Midvaal which has been receiving a very decent amount of rainfall.

A little alarming so little rain is falling in the eastern Freestate. Hopefully it will improve next month for the farms in those areas.
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You cannot expect to relieve a year's worth of drought in 3 months. The system will take time to recover.
 
jingaling said:
Vaal Dam is in Midvaal which has been receiving a very decent amount of rainfall.

A little alarming so little rain is falling in the eastern Freestate. Hopefully it will improve next month for the farms in those areas.
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Rain in midvaal is largely irrelevant to the Vaal dam level. That runoff joins the system below the Vaal dam.
Vaal catchment area is around from clarens northeastwards.
 
Sinbad said:
Rain in midvaal is largely irrelevant to the Vaal dam level. That runoff joins the system below the Vaal dam.
Vaal catchment area is around from clarens northeastwards.
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Actually that isn't that catchment area persay, while quite a few rivers flow into vaal dam, the vaal river origins is actually in Ermelo and starts with the klein vaal.Nor is clarens a catchment area, Lesotho highlands water scheme feeds water into the vaal dam, Harrismith is a catchment area, the Wilge river feeds directly into the vaal dam and the wilge is fed by the klip river and elands, there is also the molspruit and grootspuit feeds into the dam.

So in actual fact the vaal dam catchment area is harrismith and KZN area, and in a small in part the klein vaal in Ermelo, both strekspruit and and lesotho highlands water scheme are inter basin water transfer scheme, so isn't a natural catchment area.

If you Look at The NOAA map you will see very little rain in the natural catchment area as well as the inter basin water transfer scheme in Lesotho.
http://www.droughtsa.org.za/about-the-drought/rainfall-data.html

I am in the brown area, close to where the Lesothto, Freestate and Eastern cape borders meet however it isn't entirely accurate, for those 3 months we definitely didn't have in the 75mm range as the area was mostly isolated thunderstorms, the quite often missed our area entirely.

At least we are getting some rain right now about 15mm so far....
 
Sinbad said:
Rain in midvaal is largely irrelevant to the Vaal dam level. That runoff joins the system below the Vaal dam.
Vaal catchment area is around from clarens northeastwards.
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Vaal Dam rose from 26 percent on 15th November to 41.5 percent on 21st December. Surely that can't just be the catchment areas, and rain falling into Vaal Dam helps too? The dam is 320 square kilometres. It's massive.
 
jingaling said:
Vaal Dam rose from 26 percent on 15th November to 41.5 percent on 21st December. Surely that can't just be the catchment areas, and rain falling into Vaal Dam helps too? The dam is 320 square kilometres. It's massive.
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Rain on a dam makes a negligible difference to its level....
 
jingaling said:
What caused the significant increase in water levels if there was little rainfall in the catchment areas?
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Little rainfall in a catchment area makes a much bigger difference than lots of rain on a dam
 
ToxicBunny said:
Little rainfall in a catchment area makes a much bigger difference than lots of rain on a dam
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Aha, thanks for expanding. If I understand correctly, the catchment areas combined make up a much bigger surface area than the dam?
 
jingaling said:
Aha, thanks for expanding. If I understand correctly, the catchment areas combined make up a much bigger surface area than the dam?
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Very much so....

You are looking at orders of magnitude bigger surface area... which is why 1mm in that catchment area will dwarf 30 or 40mm on the dam itself
 
For every mm of rain you get one liter per square meter. The total volume of the Vaal dam is approximately 2,609,799,000 cubic metres or 2609799000000 liters of water. The area of the Vaal dam is 320 square kilometers or 320000000 square meters.

That therefore means that if 1mm of rain fell over the Vaal dam, 320000000 liters would have fallen into the Vaal dam. That in turn means the volume would have increased by only 0,0122615%. Going by that, if it rained 100mm directly over the Vaal dam, the volume should increase by 1.22615%.

Bottom line, it should rain a LOT more directly over the Vaal dam to make any significant contribution.
 
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