(CNN) -- An Egyptian who was once a Special Forces officer has been chosen "caretaker" leader of al Qaeda in the wake of Osama bin Laden's death, according to a source with detailed knowledge of the group's inner workings. Al Qaeda's interim leader is Saif al-Adel, who has long played a prominent role in the group, according to Noman Benotman. Benotman has known the al Qaeda leadership for more than two decades. He was once a leader of the Libyan Islamic Fighting Group (LIFG), a militant organization that used to be aligned with al Qaeda, but in recent years renounced al Qaeda's ideology. Benotman told CNN that based on his personal communications with militants and discussions on jihadist forums, al-Adel, also known as Muhamad Ibrahim Makkawi, had been chosen interim chief of al Qaeda because the global jihadist community had grown restive in recent days about the lack of a formal announcement of a successor to bin Laden. U.S.: Bin Laden communicated with Yemen group According to Benotman, this was not a decision of the formal shura council of al Qaeda, because it is currently impossible to gather them in one place, but was rather the decision of six to eight leaders of al Qaeda in the Afghanistan-Pakistan border area. Al-Adel was already one of the top leaders of the group. Bin Laden's money trail Stop the money, defeat al Qaeda RELATED TOPICS Al Qaeda Libyan Islamic Fighting Group Osama bin Laden Terrorism Egypt However, Benotman said, the choice of an Egyptian may not sit well with some Saudi and Yemeni members of al Qaeda, who believe bin Laden's successor should come from the Arabian Peninsula, a region that is holy to all Muslims. Bin Laden was from a wealthy Saudi family. The presumed successor to bin Laden is his long-time deputy, Ayman al-Zawahiri, who is also Egyptian. Benotman, who has long been a reliable source of information about al Qaeda, said the temporary appointment of al-Adel may be a way for the leadership to gauge reaction to the selection of someone from beyond the Arabian Peninsula as the group's leader. Al-Adel fought the Soviets in Afghanistan during the 1980s. After the fall of the Taliban in the winter of 2001 he fled to Iran. According to senior Saudi counterterrorism officials, from there al-Adel authorized al Qaeda's branch in Saudi Arabia to begin a campaign of terrorist attacks in the Saudi kingdom that began in Riyadh in May 2003, a campaign that killed scores. Some reports in the past year have suggested that al-Adel had left Iran for Pakistan. Pakistan announces key al Qaeda arrest One of the key issues that al-Adel has to reckon with now is the fallout from the large quantities of sensitive information that was recovered by U.S. forces at the compound in Abbottabad, Pakistan, where bin Laden was shot on May 2. That information is likely to prove damaging to al Qaeda operations. The selection of an interim leader allows al Qaeda to begin the process of collecting allegiance, or baya, from al-Qaeda affiliates such as the Yemen-based al Qaeda in the Arabian Peninsula and the North Africa-based al Qaeda in the Islamic Maghreb. Baya was a religious oath of allegiance to bin Laden rather than to the organization itself, in the same way that Nazi Party members swore an oath of fealty to Hitler rather than to Nazism. That baya must now be transferred to whomever the new leader of al Qaeda is going to be, which is likely to be al-Zawahiri, given his long role as bin Laden's deputy. Opinion: Why bin Laden was radicalized However, there is scant evidence that al-Zawahiri has the charisma of bin Laden, nor that he commands the respect bordering on love that was accorded to bin Laden by members of al Qaeda. Now that bin Laden is dead there is a real opportunity for the Taliban to disassociate itself from al Qaeda, as it was bin Laden who, sometime before the 9/11 attacks, swore an oath of allegiance to Taliban leader Mullah Omar as the Amir al-Muminin, "commander of the faithful," a rarely invoked religious title that dates from around the time of the Prophet Mohammed. Mullah Omar could now take the position that the new leader of al Qaeda does not need to swear an oath of allegiance to Omar as commander of the faithful. Such a move would satisfy a key condition for peace talks with the U.S. and Afghan governments: that the Taliban reject al Qaeda, something that they have so far not done. Al-Adel has been involved in militant activities since the late 1980s, according to an interview with him published in spring 2005 in the Arabic-language London-based daily Al-Quds al-Arabi. In the article, written by Fuad Husayn, a Jordanian journalist and writer, al-Adel recalled that he was detained for militant activities in Egypt on May 6, 1987. Al Qaeda's most-wanted leaders "The case pertained to the assassination attempt against ex-Egyptian Interior Minister Hasan Abu-Basha. ... I was then a colonel in the Egyptian Special Forces," he said. Al-Adel also has been involved for years in anti-American activities, other sources indicate. Mohamed Odeh, one of the bombers of the U.S. Embassy in Kenya in August 1998, told FBI interrogators that in 1993 he was ordered by al-Adel to go to Somalia to link up with local tribes and train them to fight and attack U.S. forces who were then serving there in a humanitarian mission to feed starving Somalis. And a British-Ugandan, Feroz Ali Abbasi, who had trained in an al-Qaeda training camp in Afghanistan before 9/11, recalled in a memoir that Adel instructed him and other recruits to fight U.S. forces around Kabul or in the southern city of Kandahar during the American invasion of Afghanistan in the fall of 2001 In the interview published in Al-Quds al-Arabi, al-Adel also explained al Qaeda's motivations for the 9/11 attack: "Our main objective, therefore, was to deal a strike to the head of the snake at home to smash its arrogance." After the fall of the Taliban, Adel recalled that he and other members of al-Qaeda found refuge in Iran: "We began to converge on Iran one after the other," he said. "...We began to rent apartments for the fraternal brothers and some of their families. The fraternal brothers of the group of Gulbuddin Hekmatyar" -- an Afghan militant then living in exile in Iran who is now a leader of the insurgency in Afghanistan -- "offered us satisfactory help in this field. They provided us with apartments and some farms that they owned." But Al-Adel said that the Iranians subsequently arrested a large number of these "brothers."

Vidalia, Louisiana - Large containers stacked two and three high Tuesday surrounded riverfront properties in Vida, Louisiana, Tuesday as residents and officials braced for flooding from the rising Mississippi.

The Coast Guard on Tuesday reopened a section of the river there that it had closed to prevent damage to levees from passing barges.

But officials said only one tow vessel at a time will be allowed to pass through the 15-mile area near Vidalia and Natchez, Mississippi. And they warned they could shut the waterway again if water levels rise.

"We will continue to closely monitor transits through the area to ensure the safety of the communities, as well as the towing vessels and their crews," Coast Guard Capt. Michael Gardiner said in a statement.

Vidalia Mayor Hyram Copeland said the prospect of flooding was a devastating threat in a city that relies on its Mississippi River waterfront.

"It's a lifeline of our communities. ... Sometimes it tells you, 'Hey, you think you have me controlled. Let me show you. ... Hopefully one of these days we can control it a little bit more than we have, but it's the mighty Mississippi," he said.

CNN's 'Flood Cam' explained

Rising waters force woman to leave home

Town under pressure as river crests

Disaster averted in New Orleans

RELATED TOPICS

• Mississippi River
• Floods
• Atchafalaya River

The river drew to within a finger's length of the highest level recorded at Greenville, Mississippi, as a flood of historic proportions continued to slink its way to the Gulf of Mexico.

Levees along the length of the river appeared to be holding and water diverted through spillways seemed to be rising more slowly than expected, but Louisiana Gov. Bobby Jindal warned residents there's plenty that could go wrong.

"There's still an awful lot of water headed our way, and it's going to be here in many cases for weeks, not just a few days," he said.

HESCO Bastions, which are filled with sand or other material, surround two medical facilities, a hotel and the Vidalia Conference and Convention Center, said city spokeswoman Sheri Rabb. Asked about the bastions' impact, Rabb said: "Unbelievable."

Despite the canceling of convention meetings for May and June, people in the coastal city are going about their daily routine, Rabb said.

"We're big-time open for business," she said.

Sandbags are keeping water out of the convention center, Rabb said Tuesday afternoon, but water covers parking lots and other portions of the riverfront. "We hope to reopen by the end of June."

The city's water supply is thought to be in good shape.

The U.S. Coast Guard reported river closures near Berwick and Morgan City, Louisiana, and at Bayou Chene, where workers submerged a barge to divert floodwaters into wetlands and away from populated areas.

In Mississippi, 4,937 people have been displaced by flooding so far, said Jeff Rent, a spokesman for the state Emergency Management Agency.

In Louisiana, more than 4,000 people had evacuated, Jindal said, citing figures compiled by parish authorities. But, he said, no shelters have been opened in the state.

The crest began passing to little effect Tuesday in Greenville.

A few minor sinkholes have popped up around the Greenville area, but the local levee board has quickly patched them up, Mytries Sutton of the Washington County Emergency Management Agency said Tuesday. Fewer than 100 structures have been flooded, she said.

The river was cresting Tuesday at Greenville, the National Weather Service reported, with an afternoon reading of 64.18 feet, more than 16 feet above flood stage.

By the weekend, floodwaters are expected to peak at record levels in Vicksburg, Mississippi, and Natchez, as well as in Red River Landing and Baton Rouge, Louisiana, according to the weather service.

"It is very difficult to grasp the idea of the possibility of our communities flooding," said Mary Beth Hanks, who has a home in New Roads and a fishing camp in Batchelor, Louisiana. "What would we do? Where do we go?"

In Louisiana's Atchafalaya River basin, residents packed up treasured possessions and scrambled to build makeshift levees as federal authorities diverted more water from the swollen Mississippi.

For the first time in its history, the U.S. Army Corps of Engineers has opened three floodways, one in Missouri and two in Louisiana, to ease pressure on levees the length of the river and reduce the possibility of devastating flooding in highly populated areas.

The Corps of Engineers opened two gates in the Morganza Spillway in Louisiana on Saturday, the first release from the facility since 1973. By Monday night, 15 of the structure's 125 bays had been opened, diverting about 102,000 cubic feet (763,000 gallons) of water per second, Corps spokeswoman Rachel Rodi said.

The plan is eventually to open about a quarter of the spillway, according to the agency.

At the Bonne Carre Spillway, which feeds into Lake Pontchartrain, 330 of 350 bays were open, with water coursing through it well above its rated capacity.

"On the river side of the spillway ... the water flowing was rather calm, but as the force of water rushed through the bays, you see its tremendous power," said Diane Truax, a Norco resident, who has been keeping a close eye on the river.

In St. Landry Parish, which is expected to receive some of the water released through the Morganza Spillway, Sheriff Bobby J. Guidroz said that while the National Guard is hard at work building a levee to protect a refinery in Krotz Springs, the biggest job for his deputies is trying to prevent looters from rifling the homes of evacuated residents.

"We're out in boats, trucks and cars," he said.

Butte Larose, Louisiana, where predictions of up to 15 feet of water drove most residents of the 600-home community to evacuate, was a virtual ghost town.

"I moved everything out of the bottom and put everything I could upstairs and brought it to my mother's house," Neil Rabeaix of Butte Larose told CNN affiliate WWL-TV in New Orleans.

Brandi Chiassom loaded a truck full of personal belongings from a home that had just been remodeled.

"All that work. There's nothing we can do. We just pray for the best," Chiassom told CNN affiliate WGNO-TV in New Orleans. "We pretty much know our house will be under water so we're trying to save everything we can."

Mike Stack, a Corps of Engineers spokesman, told CNN's "John King USA" that 20,000 to 25,000 homes could be flooded, but the agency and Louisiana authorities are working to limit the damage.

"The system is under tremendous pressure, and it will be for a long time, so our key concern is making sure that we're vigilant," Stack said. "We're out there on the system, making sure the system stays intact while we're still working with the communities to try to help with the flooding."

Officials said the spillway gates are likely to be open for weeks, and it will be weeks before the river falls below flood stage and those who have evacuated can safely return.

The flood is the most significant to hit the lower Mississippi River valley since at least 1937 and has so far affected nine states: Missouri, Illinois, Kentucky, Tennessee, Ohio, Indiana, Arkansas, Louisiana and Mississippi.

As many as 22 cities and communities where river levels are monitored by the U.S. government remain flooded, some of them weeks after both the Mississippi and Ohio rivers climbed out of their banks.

Across the South and lower Midwest, floodwaters have already covered about 3 million acres of farmland, eroding for many farmers what could have been a profitable year for corn, wheat, rice and cotton, officials said.

In Melville, Louisiana, the rising waters brought back bad memories from the record floods of 1973 and a sense of hopelessness as the Atchafalaya River encroached on Wendy Moreau's home.

"To be honest with you, we don't have no money to start over," she told CNN affiliate KALB-TV in Alexandria, Louisiana. "I don't know what we're going to do, we just live day to day and try to survive."