Saturday, September 23

The grim prognosis if a key dam fails in storm-battered Puerto Rico UPDATED 9/24 - 4:15 AM EDT

Engineers got the spillway open late last night, easing pressure on the cracked dam. 

Gomez noted that "there is no way to fix it" right now considering the conditions and said if the dam tops over or fails structurally, "thousands of people could die." ... The Puerto Rico Electric Power Authority, which operates the dam, says that the failure is already causing flash flooding downstream. 

A flash flood emergency has been issued out of concern that Guajataca Dam is at risk of "imminent" failure. 

The good news is that the dam is still holding, and that initial reports might -- might -- have overstated the estimated number of people (70,000) who need to be evacuated. The situation is very confused as of about 4:00 PM today when the following report was filed. 

No, the floodgates can't be opened to take pressure off the cracked dam, as they were for another dam in Puerto Rico in danger of overflowing (Rio La Plata Dam in Tojo Baja). This is because the storm damaged the mechanical gates at the Guajataca Dam, making it "impossible" to open them automatically. In addition, the opening of the gates at Rio La Plata still created significant flooding in Tojo Baja.) 

As to whether the damaged gates could be opened manually -- I do not know; in any case there is no mention in news reports about this possibility, not any I've seen. 

From a New York Times report, Hurricane Maria Live Updates: Structural Damage at Dam Prompts Evacuations in Puerto Rico, filed Friday evening:

According to the United States Army Corps of Engineers, Guajataca Dam is an earthen structure, 120 feet high and nearly 1,000 feet long. It was built in the mid-1920s by the Army Corps of Engineers, but is now owned by the power authority.

It lies across the Guajataca River, forming a reservoir that can hold about 11 billion gallons of water that is used for drinking, irrigation and power generation. ...
From the following report, here is more bad news about the imperiled dam:
  • Even with the best-case estimate, roughly 8,000 people live within the flood zone and 300 families need to be evacuated immediately. But given the dire conditions in the region in the wake of Hurricane Maria the question is "Evacuate to where?"  
  • Communication is knocked out in the affected region due to Maria, so it's hard to alert the people who most need to be evacuated.
  • The storm has made quick evacuation impossible because of bad road conditions from the storm; the only way into the region right now is by helicopter.
'Hysteria Is Starting to Spread' As Humanitarian Crisis Grows in Puerto Rico After Maria
By Pam Wright
Sep 23 2017 04:00 PM EDT

[Pundita note: I don't think "hysteria" was the right term for Manati's mayor to use; more like "justifiable fear"]


In Puerto Rico, vital supplies are running low in some towns – even in the shelters.

The humanitarian crisis is growing in Puerto Rico in the wake of Hurricane Maria.

The death toll rose to 21 in the U.S. territory Friday as supplies ran low, gasoline shortages led to panic and the search for loved ones continued to be hindered by downed communication systems.

"Hysteria is starting to spread. The hospital is about to collapse. It's at capacity," Mayor Jose Sanchez Gonzalez of the north coastal town of Manati told the Associated Press Saturday, crying. "We need someone to help us immediately."

Puerto Rico Gov. Ricardo Rosselló told The Weather Channel they were attempting to reach the most remote areas of the island by helicopter, as travel has been crippled by debris and downed power lines on Puerto Rico's roads. Officials said Saturday they still could not communicate with more than half the territory's towns.

On Friday evening, authorities said they ordered the evacuation of 70,000 people living downstream from the Guajataca Dam in the northwestern part of the territory amid fears that the dam would fail.

The dam continued to hold Saturday, despite a reported crack.

Javier Jimenez, the mayor of the town of San Sebastian, said he believed the number of people needing to be evacuated was far smaller than the 70,000 reported. The NWS San Juan said a population of nearly 8000 individuals lived within the area under the flash flood warning downstream from the dam, and Secretary of Public Affairs Ramon Rosario said about 300 families were in harm's way.

The AP noted that the discrepancy could not immediately be explained.

A crack was reportedly discovered by an engineer inspecting the 90-year-old Guajataca Dam, which could be the first sign of a total failure of the dam, Anthony Reynes, a meteorologist with the U.S. NWS, told the Associated Press.

"There's no clue as to how long or how this can evolve. That is why the authorities are moving so fast because they also have the challenges of all the debris. It is a really, really dire situation," Reynes said. "They are trying to mobilize all the resources they can but it's not easy. We really don't know how long it would take for this failure to become a full break of the dam."

Puerto Rico Gov. Ricardo Rosselló implored people in the flood zone to evacuate immediately.

Abner Gomez, executive director of Puerto Rico's emergency management agency, told the New York Post Friday that the dam's floodgates suffered mechanical damage during the storm, which made it impossible for authorities to open and let out normal water currents.

Gomez noted that "there is no way to fix it" right now considering the conditions and said if the dam tops over or fails structurally, "thousands of people could die."

The dam lies across the Guajataca River to form a reservoir that can hold roughly 11 billion gallons of water.

According to El Nuevo Dio, government officials reported that people in one small community near the dam refused to evacuate. Authorities intended to enforce a law that allows responders to evacuate children and the elderly in an emergency.

A flash flood warning continues for Isabella and Quebradillas, the NWS says.


The report also notes:
  • Tens of thousands are without power in the Dominican Republic in the wake of the hurricane.
  • Damage is massive and more than a dozen people died on the island of Dominica, the country's prime minister announced.

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