Due to the large inflow into Lake Volta, the Volta River Authority (VRA) has activated its emergency preparedness plan and standard operating procedures, including the initiation of a controlled release of excess water from Akosombo Dam.
According to news reports, the large amount of excess water released (VRA puts it at approximately 183,000 cubic feet per second) caused unprecedented flooding in many communities, causing severe damage to homes, property, and investments. It is said that he is giving.
The reason for the flooding is that the VRA is critical to the safety of Akosombo Dam, so the spillway of Akosombo Dam must be opened to quickly release excess water that will raise the water level of Lake Volta behind the dam. Because it didn’t happen. The water level of Lake Volta exceeds the maximum design lake level of 278.0 feet.
The overarching objective of the VRA is to effectively utilize the water resources of the Volta River to generate the maximum possible power potential for Ghana.
For the purpose of this article, to effectively manage the water resources of Akosombo Dam, the VRA must undertake three interrelated activities.
manage
Management of water levels in Lake Volta. The VRA has done a pretty good job managing water levels in Lake Volta.
According to literature, the highest lake level ever recorded was 277.54 feet on November 8, 2010 (VRA source). The maximum operating water level of 278 feet was never exceeded.
However, the VRA records times when the lake level was below the minimum operational lake level of 240 feet.
On July 21, 2007, the altitude was 234.96 feet (VRA source), albeit due to a prolonged drought.
Therefore, VRA manages this activity very well.
surveillance
Monitoring inflows to Lake Volta: VRA, as one of Ghana’s best-performing public institutions, should implement a comprehensive reservoir simulation and management model.
Such a system should ideally allow sufficient time to predict changes in lake water levels at the dam site.
I was therefore surprised to read a news report recently in which the VRA admitted it lacked the ability to predict when the current spill exercise would end.
In the news article, a VRA executive was quoted as saying, “I don’t know the specifics.”
We hope this will stop within about a week, but it is likely that this situation will continue, even though it is expected that levels may drop…” Akosombo Dam Spill: VRA When Exercise Will End Unknown, (October 13, 2023.
This is unacceptable to the VRA.
regulate
Regulation of outflow from Akosombo Dam: With the main objective of optimal power generation, VRA ensures the release of the right amount of surplus water and closes the spillway gates at the right time to ensure outflow. I’ll definitely aim for it. The lake level remained very close to high water level.
Any spill that results in a lower than necessary drop in the lake’s water level is a failure because it ultimately affects the maximum power that could otherwise be generated in the future. How well does VRA walk this thin line?
This year, opening the spillway gates on September 15, 2023 in response to rising lake levels appears to have been insufficient and too late.
As of Friday, October 13, 2023, four of the 12 spillway gates were fully open after the initial Phase 1 opening, creating a thunderous spectacle. Unfortunately, it’s wreaking havoc downstream.
The immediate danger is that the VRA notes that current inflows are in excess of 400,000 cubic feet per second, while outflows are near 183,000 cubic feet per second.
My prayer is that the reservoir will be able to contain the additional charges due to the approximately 200,000 cubic feet per second of net inflow and remain below the critical water level of 278 feet.
In the future, how will the surplus water from Akosombo Dam be released in small amounts over a long period of time to protect lives and property in the downstream areas of the dam?
This is the challenge VRA now faces. Thankfully, VRA should have the resources to fix this problem.
The author is a civil/irrigation engineer